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7th Semester Question Bank, ECE Anna university

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7th Semester Question Bank, ECE Anna university Powered By Docstoc
					7TH SEM Q&A COLLECTION
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Oxide house of Publishing, India.

http://tamiltel.tk 

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                                             Contents


S.No   Subject                                 Pg.No


1      Digital Image processing ……………          1

2      Microwave Engineering ………………            38

3      Optical Communication ………………            64

4      Television and Video Engineering ….     90

5      VLSI Design …………………………….                111

6      Computer Hardware and Interfacing       146
DIGITAL
 IMAGE
  PROCESSING




               1
                                        2 MARKS

                                            UNIT I
1. Define Image?
         An image may be defined as two dimensional light intensity function f(x, y)
where x and y denote spatial co-ordinate and the amplitude or value of f at any point
(x, y) is called intensity or grayscale or brightness of the image at that point.

2. What is Dynamic Range?
       The range of values spanned by the gray scale is called dynamic range of an
image. Image will have high contrast, if the dynamic range is high and image will have
dull washed out gray look if the dynamic range is low.
3. Define Brightness?
        Brightness of an object is the perceived luminance of the surround. Two objects
with different surroundings would have identical luminance but different brightness.
4. Define Tapered Quantization?
       If gray levels in a certain range occur frequently while others occurs rarely, the
quantization levels are finely spaced in this range and coarsely spaced outside of it. This
method is sometimes called Tapered Quantization.
5. What do you meant by Gray level?
       Gray level refers to a scalar measure of intensity that ranges from black to grays
and finally to white.
6. What do you meant by Color model?
        A Color model is a specification of 3D-coordinates system and a subspace within
that system where each color is represented by a single point.
7. List the hardware oriented color models?
        1. RGB model
        2. CMY model
        3. YIQ model
        4. HSI model

8. What is Hue of saturation?
      Hue is a color attribute that describes a pure color where saturation gives a
measure of the degree to which a pure color is diluted by white light.




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9. List the applications of color models?
1. RGB model--- used for color monitor & color video camera
2. CMY model---used for color printing
3. HIS model----used for color image processing
4. YIQ model---used for color picture transmission

10. What is Chromatic Adoption?
`       The hue of a perceived color depends on the adoption of the viewer. For example,
the American Flag will not immediately appear red, white, and blue of the viewer has
been subjected to high intensity red light before viewing the flag. The color of the flag
will appear to shift in hue toward the red component cyan.
11. Define Resolutions?
        Resolution is defined as the smallest number of discernible detail in an image.
Spatial resolution is the smallest discernible detail in an image and gray level resolution
refers to the smallest discernible change is gray level.
12. What is meant by pixel?
        A digital image is composed of a finite number of elements each of which has a
particular location or value. These elements are referred to as pixels or image elements or
picture elements or pels elements.

13. Define Digital image?
       When x, y and the amplitude values of f all are finite discrete quantities , we call
the image digital image.

14. What are the steps involved in DIP?
      1. Image Acquisition
      2. Preprocessing
      3. Segmentation
      4. Representation and Description
      5. Recognition and Interpretation

15. What is recognition and Interpretation?
       Recognition means is a process that assigns a label to an object based on the
information provided by its descriptors.
       Interpretation means assigning meaning to a recognized object.

16. Specify the elements of DIP system?
       1. Image Acquisition
       2. Storage
       3. Processing
       4. Display
17. Explain the categories of digital storage?
       1. Short term storage for use during processing.
       2. Online storage for relatively fast recall.
       3. Archical storage for infrequent access.



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18. What are the types of light receptors?
       The two types of light receptors are
             1. Cones and
             2. Rods
19. Differentiate photopic and scotopic vision?

              Photopic vision                      Scotopic vision
   1. The human being can resolve          Several rods are connected to
   the fine details with these cones       one nerve end. So it gives the
   because each one is connected to        overall picture of the image.
   its own nerve end.
   2. This is also known as bright         This is also known as thin light
   light vision.                           vision.

20. How cones and rods are distributed in retina?
       In each eye, cones are in the range 6-7 million and rods are in the range 75-150
million.

21. Define subjective brightness and brightness adaptation?
         Subjective brightness means intensity as preserved by the human visual system.
         Brightness adaptation means the human visual system can operate only from
scotopic to glare limit. It cannot operate over the range simultaneously. It accomplishes
this large variation by changes in its overall intensity.

22. Define weber ratio
        The ratio of increment of illumination to background of illumination is called as
weber ratio.(ie) ∆i/i
        If the ratio (∆i/i) is small, then small percentage of change in intensity is needed
(ie) good brightness adaptation.
        If the ratio (∆i/i) is large , then large percentage of change in intensity is needed
(ie) poor brightness adaptation.

23. What is meant by machband effect?
        Machband effect means the intensity of the stripes is constant. Therefore it
preserves the brightness pattern near the boundaries, these bands are called as machband
effect.

24. What is simultaneous contrast?
       The region reserved brightness not depend on its intensity but also on its
background. All centre square have same intensity. However they appear to the eye to
become darker as the background becomes lighter.

25. What is meant by illumination and reflectance?
         Illumination is the amount of source light incident on the scene. It is represented
as i(x, y).




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       Reflectance is the amount of light reflected by the object in the scene. It is
represented by r(x, y).

26. Define sampling and quantization
       Sampling means digitizing the co-ordinate value (x, y).
       Quantization means digitizing the amplitude value.

27. Find the number of bits required to store a 256 X 256 image with 32 gray levels?
       32 gray levels = 25
                      = 5 bits
       256 * 256 * 5 = 327680 bits.

28. Write the expression to find the number of bits to store a digital image?
      The number of bits required to store a digital image is
                       b=M X N X k
               When M=N, this equation becomes
                       b=N^2k
30. What do you meant by Zooming of digital images?
        Zooming may be viewed as over sampling. It involves the creation of new pixel
locations and the assignment of gray levels to those new locations.

31. What do you meant by shrinking of digital images?
        Shrinking may be viewed as under sampling. To shrink an image by one half, we
delete every row and column. To reduce possible aliasing effect, it is a good idea to blue
an image slightly before shrinking it.
32. Write short notes on neighbors of a pixel.
        The pixel p at co-ordinates (x, y) has 4 neighbors (ie) 2 horizontal and 2 vertical
neighbors whose co-ordinates is given by (x+1, y), (x-1,y), (x,y-1), (x, y+1). This is
called as direct neighbors. It is denoted by N4(P)
        Four diagonal neighbors of p have co-ordinates (x+1, y+1), (x+1,y-1), (x-1, y-1),
(x-1, y+1). It is denoted by ND(4).
        Eight neighbors of p denoted by N8(P) is a combination of 4 direct neighbors and
4 diagonal neighbors.

33. Explain the types of connectivity.
       1. 4 connectivity
       2. 8 connectivity
       3. M connectivity (mixed connectivity)

34. What is meant by path?
       Path from pixel p with co-ordinates (x, y) to pixel q with co-ordinates (s,t) is a
sequence of distinct pixels with co-ordinates.




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35. Give the formula for calculating D4 and D8 distance.
       D4 distance ( city block distance) is defined by
               D4(p, q) = |x-s| + |y-t|
       D8 distance(chess board distance) is defined by
               D8(p, q) = max(|x-s|, |y-t|).

36. What is geometric transformation?
      Transformation is used to alter the co-ordinate description of image.
      The basic geometric transformations are
      1. Image translation
      2. Scaling
      3. Image rotation

37. What is image translation and scaling?
        Image translation means reposition the image from one co-ordinate location to
another along straight line path.
        Scaling is used to alter the size of the object or image (ie) a co-ordinate system is
scaled by a factor.

38. What is the need for transform?
        The need for transform is most of the signals or images are time domain signal
(ie) signals can be measured with a function of time. This representation is not always
best. For most image processing applications anyone of the mathematical transformation
are applied to the signal or images to obtain further information from that signal.

39. Define the term Luminance?
       Luminance measured in lumens (lm), gives a measure of the amount of energy an
observer perceiver from a light source.
40. What is Image Transform?
       An image can be expanded in terms of a discrete set of basis arrays called basis
images. These basis images can be generated by unitary matrices. Alternatively, a given
NxN image can be viewed as an N^2x1 vectors. An image transform provides a set of
coordinates or basis vectors for vector space.

41. What are the applications of transform.
1) To reduce band width
2) To reduce redundancy
3) To extract feature.

42. Give the Conditions for perfect transform?
Transpose of matrix = Inverse of a matrix.
Orthoganality.

43. What are the properties of unitary transform?
     1) Determinant and the Eigen values of a unitary matrix have unity magnitude



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       2) the entropy of a random vector is preserved under a unitary Transformation
       3) Since the entropy is a measure of average information, this means information
        is preserved under a unitary transformation.

44. Define fourier transform pair?
       The fourier transform of f(x) denoted by F(u) is defined by
                ∝
       F(u)= ∫ f(x) e-j2πux dx ----------------(1)
            -∝
       The inverse fourier transform of f(x) is defined by
                ∝
       f(x)= ∫F(u) ej2πux dx --------------------(2)
            -∝
       The equations (1) and (2) are known as fourier transform pair.

45. Define fourier spectrum and spectral density?
       Fourier spectrum is defined as
              F(u) = |F(u)| e jφ(u)
              Where
              |F(u)| = R2(u)+I2(u)
              φ(u) = tan-1(I(u)/R(u))
       Spectral density is defined by
              p(u) = |F(u)|2
              p(u) = R2(u)+I2(u)

46. Give the relation for 1-D discrete fourier transform pair?
       The discrete fourier transform is defined by
                          n-1
       F(u) = 1/N ∑ f(x) e –j2πux/N
                          x=0

        The inverse discrete fourier transform is given by
                    n-1
       f(x) =   ∑ F(u) e j2πux/N
               x=0
       These equations are known as discrete fourier transform pair.
47. Specify the properties of 2D fourier transform.
       The properties are
       1. Separability
       2. Translation
       3. Periodicity and conjugate symmetry
       4. Rotation
       5. Distributivity and scaling
       6. Average value
       7. Laplacian
       8. Convolution and correlation
       9. sampling



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48. Explain separability property in 2D fourier transform
       The advantage of separable property is that F(u, v) and f(x, y) can be obtained by
successive application of 1D fourier transform or its inverse.
              n-1
        F(u, v) =1/N ∑ F(x, v) e –j2πux/N
              x=0
Where
                    n-1
   F(x, v)=N[1/N ∑ f(x, y) e –j2πvy/N
                    y=0

49. Properties of twiddle factor.
       1. Periodicity
               WN^(K+N)= WN^K

        2. Symmetry
              WN^(K+N/2)= -WN^K

50. Give the Properties of one-dimensional DFT
      1. The DFT and unitary DFT matrices are symmetric.
      2. The extensions of the DFT and unitary DFT of a sequence and their
          inverse transforms are periodic with period N.
      3. The DFT or unitary DFT of a real sequence is conjugate symmetric
          about N/2.

51. Give the Properties of two-dimensional DFT
      1. Symmetric
      2. Periodic extensions
      3. Sampled Fourier transform
      4. Conjugate symmetry.

52. What is meant by convolution?
       The convolution of 2 functions is defined by
f(x)*g(x) = f(α) .g(x- α) dα
where α is the dummy variable

53. State convolution theorem for 1D
               If f(x) has a fourier transform F(u) and g(x) has a fourier transform G(u)
       then f(x)*g(x) has a fourier transform F(u).G(u).
               Convolution in x domain can be obtained by taking the inverse fourier
       transform of the product F(u).G(u).
               Convolution in frequency domain reduces the multiplication in the x
       domain
               F(x).g(x)      F(u)* G(u)
       These 2 results are referred to the convolution theorem.




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54. What is wrap around error?
             The individual periods of the convolution will overlap and referred to as
      wrap around error

55. Give the formula for correlation of 1D continuous function.
               The correlation of 2 continuous functions f(x) and g(x) is defined by
       f(x) o g(x) = f*(α ) g(x+α ) dα

56. What are the properties of Haar transform.

        1. Haar transform is real and orthogonal.
        2. Haar transform is a very fast transform
        3. Haar transform has very poor energy compaction for images
        4. The basic vectors of Haar matrix sequensly ordered.

57. What are the Properties of Slant transform

        1. Slant transform is real and orthogonal.
        2. Slant transform is a fast transform
        3. Slant transform has very good energy compaction for images
        4. The basic vectors of Slant matrix are not sequensely ordered.

58. Specify the properties of forward transformation kernel?

        The forward transformation kernel is said to be separable if g(x, y, u, v)
        g(x, y, u, v) = g1(x, u).g2(y, v)
        The forward transformation kernel is symmetric if g1 is functionally equal to g2
        g(x, y, u, v) = g1(x, u). g1(y,v)

59. Define fast Walsh transform.

        The Walsh transform is defined by
            n-1      x-1
w(u) = 1/N ∑ f(x) π (-1) bi(x).bn-1-i   (u)

           x=0    i=0

60. Give the relation for 1-D DCT.

     The 1-D DCT is,
              N-1
    C(u)=α(u)∑ f(x) cos[((2x+1)uп)/2N]       where u=0,1,2,….N-1
              X=0
                  N-1
    Inverse f(x)= ∑ α(u) c(u) cos[((2x+1) uп)/2N] where x=0,1,2,…N-1
                  V=0




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61.Write slant transform matrix SN.

                                                                     0
                                                  1   0
                       1        0      0
                                                 -aN bN
                      aN       bN                                              S      0
                                                                              N/2
                           0        I(N/2-1)           0          I(N/2-1)

   SN = 1/√2           1   0                      0          -1
                                       0                             0
                      -bN aN                      bN        aN                       S
                                                                               0    N/2
                           0        I(N/2-1)           0          -I(N/2-1)




62. Define Haar transform.
    The Haar transform can be expressed in matrix form as,
               T=HFH
               Where F = N X N image matrix
                     H = N X N transformation matrix
                     T = resulting N X N transform.

63. Define K-L transform.
    Consider a set of n or multi-dimensional discrete signal represented as column vector
       x1,x2,…xn each having M elements,

             X1
             X2
   X=           .
              .
             Xn

   The mean vector is defined as Mx=E{x}
   Where E{x} is the expected value of x.     M
   For M vector samples mean vector is Mx=1/M ∑ Xk
                                              K=1
                                                T
      The co-variant matrix is, Cx=E{(X-Mx)(X-Mx)}
   Where T-vector transposition X->N-D vector
   Cx->nxn matrix.         M               T
   For M samples, Cx=1/M ∑ (xk-Mx)(xk-Mx).
                           K=1

               K-L Transform Y= A(X- MX)



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                                     UNIT II


1. Specify the objective of image enhancement technique.

    The objective of enhancement technique is to process an image so that the result
is more suitable than the original image for a particular application.

2. Explain the 2 categories of image enhancement.

       i)      Spatial domain refers to image plane itself & approaches in this
               category are based on direct manipulation of picture image.
       ii)     Frequency domain methods based on modifying the image by fourier
               transform.

3. What is contrast stretching?
Contrast stretching reduces an image of higher contrast than the original by darkening
the levels below m and brightening the levels above m in the image.

4. What is grey level slicing?
Highlighting a specific range of grey levels in an image often is desired. Applications
include enhancing features such as masses of water in satellite imagery and enhancing
flaws in x-ray images.

5. Define image subtraction.
The difference between 2 images f(x,y) and h(x,y) expressed as,
         g(x,y)=f(x,y)-h(x,y)
is obtained by computing the difference between all pairs of corresponding pixels
from f and h.

6. What is the purpose of image averaging?
 An important application of image averagingis in the field of astronomy, where
imaging with very low light levels is routine, causing sensor noise frequently to
render single images virtually useless for analysis.

7. What is meant by masking?
Mask is the small 2-D array in which the values of mask co-efficient determines the
nature of process.
      The enhancement technique based on this type of approach is referred to as
mask processing.

8. Give the formula for negative and log transformation.
          Negative: S=L-1-r
          Log: S = c log(1+r)
   Where c-constant and r≥0




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9. What is meant by bit plane slicing?
    Instead of highlighting gray level ranges, highlighting the contribution made to
total image appearance by specific bits might be desired. Suppose that each pixel in
an image is represented by 8 bits. Imagine that the image is composed of eight 1-bit
planes, ranging from bit plane 0 for LSB to bit plane-7 for MSB.

10. Define histogram.
    The histogram of a digital image with gray levels in the range [0, L-1] is a
discrete function h(rk)=nk.
    rk-kth gray level
    nk-number of pixels in the image having gray level rk.

11. What is meant by histogram equalization?
                 k         k
            Sk= T(rk) = ∑ Pr(rj) = ∑ nj/n        where k=0,1,2,….L-1
                        j=0         j=0
    This transformation is called histogram equalization.

12. Differentiate linear spatial filter and non-linear spatial filter.

       s.no.             Linear spatial filter                   Non-linear spatial filter

      1.           Response is a sum of products of          They do not explicitly use co-
                   the filter co-efficient.                  efficients in the sum-of-products.

      2.           R = w(-1,-1) f(x-1,y-1) +                 R = w1z1 + w2z2 + … +w9z9
                      w(-1,0) f(x-1,y) + … +                      9
                      w(0,0) f(x,y) + … +                      = ∑ wizi
                      w(1,0) f(x+1,y) +                          i=1
                      w(1,1) f(x+1,y+1).

13. Give the mask used for high boost filtering.




               0         -1      0                          -1     -1       -1

               -1       A+4      -1                         -1    A+8       -1

               0         -1      0                          -1     -1       -1




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   14. What is meant by laplacian filter?
   The laplacian for a function f(x,y) of 2 variables is defined as,
                   2    2     2 2         2
                ▼f = ∂ f / ∂ x + ∂ f / ∂ y

   15. Write the steps involved in frequency domain filtering.
                                             x+y
        1. Multiply the input image by (-1)        to center the transform.
        2. Compute F(u,v), the DFT of the image from (1).
        3. Multiply F(u,v) by a filter function H(u,v).
        4. Compute the inverse DFT of the result in (3).
        5. Obtain the real part of the result in (4).
                                             x+y
        6. Multiply the result in (5) by (-1)

   16. Give the formula for transform function of a Butterworth low pass filter.
   The transfer function of a Butterworth low pass filter of order n and with cut off
   frequency at a distance D0 from the origin is,
                                       2n
       H(u,v) = 1 / 1 + [ D(u,v) / D0 ]
                              2        2 1/2
   Where D(u,v) = [(u – M/2) + (v-N/2) ]

   17. What do you mean by Point processing?
       Image enhancement at any Point in an image depends only on the gray level at
that point is often referred to as Point processing.
   18. What is Image Negatives?
       The negative of an image with gray levels in the range [0, L-1] is obtained by
using the negative transformation, which is given by the expression.
                                           s = L-1-r
                                       Where s is output pixel
                                                    r is input pixel
19. Define Derivative filter?
       For a function f (x, y), the gradient f at co-ordinate (x, y) is defined as the vector


 f=     ∂f/∂x
        ∂f/∂y


  f = mag ( f) = {[(∂f/∂x) 2 +(∂f/∂y) 2 ]} 1/2



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20. Explain spatial filtering?
         Spatial filtering is the process of moving the filter mask from point to point in an
image. For linear spatial filter, the response is given by a sum of products of the filter
coefficients, and the corresponding image pixels in the area spanned by the filter mask.
21. What is a Median filter?
         The median filter replaces the value of a pixel by the median of the gray levels in
the neighborhood of that pixel.
22. What is maximum filter and minimum filter?
         The 100th percentile is maximum filter is used in finding brightest points in an
image. The 0th percentile filter is minimum filter used for finding darkest points in an
image.
23. Write the application of sharpening filters?
         1. Electronic printing and medical imaging to industrial application
         2. Autonomous target detection in smart weapons.
24. Name the different types of derivative filters?
         1. Perwitt operators
         2. Roberts cross gradient operators
         3. Sobel operators




                                          UNIT III


1. What is meant by Image Restoration?
        Restoration attempts to reconstruct or recover an image that has been degraded by
using a clear knowledge of the degrading phenomenon.

2. What are the two properties in Linear Operator?
           Additivity
              Homogenity

3. Explain additivity property in Linear Operator?
       H[f1(x,y)+f2(x,y)]=H[f1(x,y)]+H[f2(x,y)]
           The additive property says that if H is the linear operator,the response to a
sum of two is equal to the sum of the two responses.



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4. How a degradation process is modeled?




                                                               η(x,y)


                              H
                                                                        g(x,y)
       f(x,y)



        A system operator H, which together with an additive white noise term η(x,y) a
operates on an input image f(x,y) to produce a degraded image g(x,y).
5. Explain homogenity property in Linear Operator?
       H[k1f1(x,y)]=k1 H[f1(x,y)]
            The homogeneity property says that,the response to a constant multiple of
any input is equal to the response to that input multiplied by the same constant.
6. Give the relation for degradation model for continuous function?
       g(x,y) =-∞∫∞∫f(α,β)§(x-α,y-β).dαdβ+η(x,y)
7. What is fredholm integral of first kind?
                    ∞
        g(x,y) = ∫∫f(α,β)h(x,α,y,β)dα dβ
                 ∞
which is called the superposition or convolution or fredholm integral of first kind. It
states that if the response of H to an impulse is known, the response to any input f(α,β)
can be calculated by means of fredholm integral.
8. Define circulant matrix?
        A square matrix, in which each row is a circular shift of the preceding row and the
first row is a circular shift of the last row, is called circulant matrix.


                he(o)    he(M-1)     he(M-2)………… he(1)
                he(1)    he(0)      he(M-1)………. he(2)
He =            .
                .
                .
                he(M-1) he(M-2) he(M-3)………. he(0)



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9. What is concept algebraic approach?
      The concept of algebraic approach is to estimate the original image which
minimizes a predefined criterion of performances.

10. What are the two methods of algebraic approach?
          o Unconstraint restoration approach
          o Constraint restoration approach

11. Define Gray-level interpolation?
               Gray-level interpolation deals with the assignment of gray levels to pixels
               in the spatially transformed image

12. What is meant by Noise probability density function?
       The spatial noise descriptor is the statistical behavior of gray level values in the
noise component of the model.

13. Why the restoration is called as unconstrained restoration?
       In the absence of any knowledge about the noise ‘n’, a meaningful criterion
function is to seek an f^ such that H f^ approximates of in a least square sense by
assuming the noise term is as small as possible.
Where H = system operator.
       f^ = estimated input image.
       g = degraded image.


14. Which is the most frequent method to overcome the difficulty to formulate the
spatial relocation of pixels?
       The point is the most frequent method, which are subsets of pixels whose location
in the input (distorted) and output (corrected) imaged is known precisely.


15. What are the three methods of estimating the degradation function?
       1. Observation
       2. Experimentation
       3. Mathematical modeling.

16. What are the types of noise models?
          Guassian noise
          Rayleigh noise



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            Erlang noise
            Exponential noise
            Uniform noise
             Impulse noise

17. Give the relation for guassian noise?
       Guassian noise:
               The PDF guassian random variable Z is given by
                      P(Z)=e-(Z-µ)2/2σ2/√2πσ
                      Z->Gray level value
                      σ->standard deviation
                      σ2->varianze of Z
                      µ->mean of the graylevel value Z

18. Give the relation for rayleigh noise?
       Rayleigh noise:
       The PDF is
               P(Z)= 2(z-a)e-(z—a)2/b/b   for Z>=a
                     0                     for Z<a

               mean                  µ=a+√πb/4
               standard deviation    σ2=b(4-π)/4

19. Give the relation for Gamma noise?
       Gamma noise:
               The PDF is
                      P(Z)=ab zb-1 ae-az/(b-1)              for Z>=0
                              0                             for Z<0
               mean                  µ=b/a
               standard deviation    σ2=b/a2

20. Give the relation for Exponential noise?
       Exponential noise
               The PDF is
                      P(Z)= ae-az  Z>=0
                              0    Z<0
               mean                µ=1/a
               standard deviation  σ2=1/a2

21. Give the relation for Uniform noise?
       Uniform noise:
               The PDF is
                      P(Z)=1/(b-a) if a<=Z<=b
                              0    otherwise
               mean                µ=a+b/2
               standard deviation  σ2=(b-a)2/12



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22. Give the relation for Impulse noise?
       Impulse noise:
               The PDF is
                      P(Z) =Pa      for z=a
                             Pb     for z=b
                             0      Otherwise
23. What is inverse filtering?
The simplest approach to restoration is direct inverse filtering, an estimate F^(u,v) of the
transform of the original image simply by dividing the transform of the degraded image
G^(u,v) by the degradation function.
        F^ (u,v) = G^(u,v)/H(u,v)
24. What is pseudo inverse filter?
        It is the stabilized version of the inverse filter.For a linear shift invariant system
with frequency response H(u,v) the pseudo inverse filter is defined as
                 H-(u,v)=1/(H(u,v)       H=/0
                           0             H=0

25. What is meant by least mean square filter?
       The limitation of inverse and pseudo inverse filter is very sensitive noise.The
wiener filtering is a method of restoring images in the presence of blurr as well as noise.

26. Give the equation for singular value decomposition of an image?
       U= m=1∑rψ√λm φmT
       This equation is called as singular value decomposition of an image.

27. Write the properties of Singular value Decomposition(SVD)?
            The SVD transform varies drastically from image to image.
            The SVD transform gives best energy packing efficiency for any given
              image.
            The SVD transform is useful in the design of filters finding least
              square,minimum solution of linear equation and finding rank of large
              matrices.

28. What is meant by blind image restoration?
        An information about the degradation must be extracted from the observed image
either explicitly or implicitly.This task is called as blind image restoration.

29. What are the two approaches for blind image restoration?
          Direct measurement
             Indirect estimation

30. What is meant by Direct measurement?
       In direct measurement the blur impulse response and noise levels are first
estimated from an observed image where this parameter are utilized in the restoration.



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31. What is blur impulse response and noise levels?
       Blur impulse response: This parameter is measured by isolating an image of a
suspected object within a picture.
       Noise levels: The noise of an observed image can be estimated by measuring the
image covariance over a region of constant background luminence.

32. What is meant by indirect estimation?
        Indirect estimation method employ temporal or spatial averaging to either obtain a
restoration or to obtain key elements of an image restoration algorithm.

33. Give the difference between Enhancement and Restoration?
        Enhancement technique is based primarily on the pleasing aspects it might present
to the viewer. For example: Contrast Stretching.
        Where as Removal of image blur by applying a deblurrings function is considered
a restoration technique.




                                          UNIT IV

1. What is image compression?
       Image compression refers to the process of redundancy amount of data required to
represent the given quantity of information for digital image. The basis of reduction
process is removal of redundant data.

2. What is Data Compression?
        Data compression requires the identification and extraction of source redundancy.
In other words, data compression seeks to reduce the number of bits used to store or
transmit information.

3. What are two main types of Data compression?

   •   Lossless compression can recover the exact original data after compression. It is
       used mainly for compressing database records, spreadsheets or word processing
       files, where exact replication of the original is essential.
   •   Lossy compression will result in a certain loss of accuracy in exchange for a
       substantial increase in compression. Lossy compression is more effective when
       used to compress graphic images and digitised voice where losses outside visual
       or aural perception can be tolerated.




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4. What is the need for Compression?

In terms of storage, the capacity of a storage device can be effectively increased with
methods that compress a body of data on its way to a storage device and decompresses
it when it is retrieved.

In terms of communications, the bandwidth of a digital communication link can be
effectively increased by compressing data at the sending end and decompressing data at
the receiving end.

At any given time, the ability of the Internet to transfer data is fixed. Thus, if data can
effectively be compressed wherever possible, significant improvements of data
throughput can be achieved. Many files can be combined into one compressed document
making sending easier.

5. What are different Compression Methods?
       Run Length Encoding (RLE)
       Arithmetic coding
       Huffman coding and
       Transform coding
6. Define is coding redundancy?
       If the gray level of an image is coded in a way that uses more code words than
necessary to represent each gray level, then the resulting image is said to contain coding
redundancy.

7. Define interpixel redundancy?
        The value of any given pixel can be predicted from the values of its neighbors.
The information carried by is small. Therefore the visual contribution of a single pixel to
an image is redundant. Otherwise called as spatial redundant geometric redundant or
interpixel redundant.
        Eg: Run length coding

8. What is run length coding?
        Run-length Encoding, or RLE is a technique used to reduce the size of a repeating
string of characters. This repeating string is called a run; typically RLE encodes a run of
symbols into two bytes, a count and a symbol. RLE can compress any type of data
regardless of its information content, but the content of data to be compressed affects the
compression ratio. Compression is normally measured with the compression ratio:

9. Define compression ratio.

       Compression Ratio = original size / compressed size: 1




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10. Define psycho visual redundancy?
       In normal visual processing certain information has less importance than other
information. So this information is said to be psycho visual redundant.

11. Define encoder
       Source encoder is responsible for removing the coding and interpixel redundancy
and psycho visual redundancy.
       There are two components
              A) Source Encoder
              B) Channel Encoder

12. Define source encoder
        Source encoder performs three operations
        1) Mapper -this transforms the input data into non-visual format. It reduces the
interpixel redundancy.
        2) Quantizer - It reduces the psycho visual redundancy of the input images .This
step is omitted if the system is error free.
        3) Symbol encoder- This reduces the coding redundancy .This is the final stage of
encoding process.

13. Define channel encoder
       The channel encoder reduces reduces the impact of the channel noise by inserting
redundant bits into the source encoded data.
       Eg: Hamming code

14. What are the types of decoder?
      Source decoder- has two components
              a) Symbol decoder- This performs inverse operation of symbol encoder.
              b) Inverse mapping- This performs inverse operation of mapper.
      Channel decoder-this is omitted if the system is error free.

15. What are the operations performed by error free compression?
       1) Devising an alternative representation of the image in which its interpixel
redundant are reduced.
       2) Coding the representation to eliminate coding redundancy

16. What is Variable Length Coding?
       Variable Length Coding is the simplest approach to error free compression. It
reduces only the coding redundancy. It assigns the shortest possible codeword to the most
probable gray levels.

17. Define Huffman coding
           • Huffman coding is a popular technique for removing coding redundancy.
           • When coding the symbols of an information source the Huffman code
             yields the smallest possible number of code words, code symbols per
             source symbol.



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18. Define Block code
       Each source symbol is mapped into fixed sequence of code symbols or code
words. So it is called as block code.

19. Define instantaneous code
        A code word that is not a prefix of any other code word is called instantaneous or
prefix codeword.

20. Define uniquely decodable code
       A code word that is not a combination of any other codeword is said to be
uniquely decodable code.

21. Define B2 code
       Each code word is made up of continuation bit c and information bit which are
binary numbers. This is called B2 code or B code. This is called B2 code because two
information bits are used for continuation bits

22. Define the procedure for Huffman shift
        List all the source symbols along with its probabilities in descending order.
Divide the total number of symbols into block of equal size. Sum the probabilities of all
the source symbols outside the reference block. Now apply the procedure for reference
block, including the prefix source symbol. The code words for the remaining symbols can
be constructed by means of one or more prefix code followed by the reference block as in
the case of binary shift code.

23. Define arithmetic coding
       In arithmetic coding one to one corresponds between source symbols and code
word doesn’t exist where as the single arithmetic code word assigned for a sequence of
source symbols. A code word defines an interval of number between 0 and 1.

24. What is bit plane Decomposition?
        An effective technique for reducing an image’s interpixel redundancies is to
process the image’s bit plane individually. This technique is based on the concept of
decomposing multilevel images into a series of binary images and compressing each
binary image via one of several well-known binary compression methods.

25. What are three categories of constant area coding?
       The three categories of constant area coding are
                   • All white
                   • All black
                   • Mixed intensity.
    The most probable or frequency occurring is assign a 1 bit code ‘0’, other two
categories area assigned as 2 bit code ‘10’ and ‘11’




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26. Draw the block diagram of transform coding system

   Input image            Wavelet transform                  Quantizer        Symbol        Compressed
                                                                              encoder       image




                                  Symbol                    Inverse wavelet             Decompressed
     Compressed image             decoder                   transform                   image




27. How effectiveness of quantization can be improved?
          • Introducing an enlarged quantization interval around zero, called a dead
              zero.
          • Adapting the size of the quantization intervals from scale to scale. In
              either case, the selected quantization intervals must be transmitted to the
              decoder with the encoded image bit stream.

28. What are the coding systems in JPEG?
                    1. A lossy baseline coding system, which is based on the DCT and is
                         adequate for most compression application.
                    2. An extended coding system for greater compression, higher
                         precision or progressive reconstruction applications.
                    3. a lossless independent coding system for reversible compression.
29. What is JPEG?
        The acronym is expanded as "Joint Photographic Expert Group". It is an
international standard in 1992. It perfectly Works with color and grayscale images, Many
applications e.g., satellite, medical,...
30. What are the basic steps in JPEG?

The Major Steps in JPEG Coding involve:

               DCT (Discrete Cosine Transformation)
               Quantization
               Zigzag Scan
               DPCM on DC component
               RLE on AC Components
               Entropy Coding

31. What is MPEG?
       The acronym is expanded as "Moving Picture Expert Group". It is an international
standard in 1992. It perfectly Works with video and also used in teleconferencing



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32. Draw the JPEG Encoder.




33. Draw the JPEG Decoder.




34. What is zig zag sequence?

   The purpose of the Zig-zag Scan:

               To group low frequency coefficients in top of vector.
               Maps 8 x 8 to a 1 x 64 vector




35. Define I-frame
        I-frame is Intraframe or Independent frame. An I-frame is compressed
independently of all frames. It resembles a JPEG encoded image. It is the reference point
for the motion estimation needed to generate subsequent P and P-frame.



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36. Define P-frame
       P-frame is called predictive frame. A P-frame is the compressed difference
between the current frame and a prediction of it based on the previous I or P-frame

37. Define B-frame
        B-frame is the bidirectional frame. A B-frame is the compressed difference
between the current frame and a prediction of it based on the previous I or P-frame or
next P-frame. Accordingly the decoder must have access to both past and future reference
frames.



                                             UNIT V

1. What is segmentation?
       Segmentation subdivides on image in to its constitute regions or objects. The level
to which the subdivides is carried depends on the problem being solved .That is
segmentation should when the objects of interest in application have been isolated.

2. Write the applications of segmentation.
         * Detection of isolated points.
         * Detection of lines and edges in an image.
3. What are the three types of discontinuity in digital image?
         Points, lines and edges.
4. How the derivatives are obtained in edge detection during formulation?
     The first derivative at any point in an image is obtained by using the magnitude of
the gradient at that point. Similarly the second derivatives are obtained by using the
laplacian.
5. Write about linking edge points.
    The approach for linking edge points is to analyze the characteristics of pixels in a
small neighborhood (3x3 or 5x5) about every point (x,y)in an image that has undergone
edge detection. All points that are similar are linked, forming a boundary of pixels that
share some common properties.
6. What are the two properties used for establishing similarity of edge pixels?
    (1) The strength of the response of the gradient operator used to produce the edge
pixel.
    (2) The direction of the gradient.




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7. What is edge?
       An edge isa set of connected pixels that lie on the boundary between two regions
edges are more closely modeled as having a ramplike profile. The slope of the ramp is
inversely proportional to the degree of blurring in the edge.

8. Give the properties of the second derivative around an edge?
        * The sign of the second derivative can be used to determine whether an edge
pixel lies on the dark or light side of an edge.
        * It produces two values for every edge in an image.
        * An imaginary straightline joining the extreme positive and negative values of
the second derivative would cross zero near the midpoint of the edge.

9. Define Gradient Operator?
        First order derivatives of a digital image are based on various approximation of
    the 2-D gradient. The gradient of an image f(x,y) at location(x,y) is defined as the
    vector
     Magnitude of the vector is
         f=mag( f )=[Gx2+ Gy2]1/2
        ∞(x,y)=tan-1(Gy/Gx)
        ∞(x,y) is the direction angle of vector f

10. What is meant by object point and background point?
To execute the objects from the background is to select a threshold T that separate these
modes. Then any point (x,y) for which f(x,y)>T is called an object point. Otherwise the
point is called background point.

11. What is global, Local and dynamic or adaptive threshold?
When Threshold T depends only on f(x,y) then the threshold is called global . If T
depends both on f(x,y) and p(x,y) is called local. If T depends on the spatial coordinates x
and y the threshold is called dynamic or adaptive where f(x,y) is the original image.

12. Define region growing?
Region growing is a procedure that groups pixels or subregions in to layer regions based
on predefined criteria. The basic approach is to start with a set of seed points and from
there grow regions by appending to each seed these neighbouring pixels that have
properties similar to the seed.

13. Specify the steps involved in splitting and merging?
       Split into 4 disjoint quadrants any region Ri for which P(Ri)=FALSE.
       Merge any adjacent regions Rj and Rk for which P(RjURk)=TRUE.
       Stop when no further merging or splitting is positive.

14. What is meant by markers?
               An approach used to control over segmentation is based on markers.
marker is a connected component belonging to an image. We have internal markers,
associated with objects of interest and external markers associated with background.



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15. What are the 2 principles steps involved in marker selection?
    The two steps are
    1. Preprocessing
    2. Definition of a set of criteria that markers must satisfy.

16. Define chain codes?
                Chain codes are used to represent a boundary by a connected sequence of
straight line segment of specified length and direction. Typically this representation is
based on 4 or 8 connectivity of the segments . The direction of each segment is coded by
using a numbering scheme.

17. What are the demerits of chain code?
    * The resulting chain code tends to be quite long.
    * Any small disturbance along the boundary due to noise cause changes in the code
    that may not be related to the shape of the boundary.

18. What is thinning or skeletonizing algorithm?
           An important approach to represent the structural shape of a plane region is to
    reduce it to a graph. This reduction may be accomplished by obtaining the
    skeletonizing algorithm. It play a central role in a broad range of problems in image
    processing, ranging from automated inspection of printed circuit boards to counting
    of asbestos fibres in air filter.

19. Specify the various image representation approaches
      • Chain codes
      • Polygonal approximation
      • Boundary segments

20. What is polygonal approximation method ?
     Polygonal approximation is a image representation approach in which a digital
boundary can be approximated with arbitary accuracy by a polygon.For a closed curve
the approximation is exact when the number of segments in polygon is equal to the
number of points in the boundary so that each pair of adjacent points defines a segment in
the polygon.

21. Specify the various polygonal approximation methods
          • Minimum perimeter polygons
          • Merging techniques
          • Splitting techniques

22. Name few boundary descriptors
            • Simple descriptors
            • Shape numbers
            • Fourier descriptors




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23. Give the formula for diameter of boundary
     The diameter of a boundary B is defined as
           Diam(B)=max[D(pi,pj)]
                       i,j
                D-distance measure
                pi,pj-points on the boundary
24. Define length of a boundary.
      The length of a boundary is the number of pixels along a boundary.Eg.for a chain
coded curve with unit spacing in both directions the number of vertical and horizontal
components plus √2 times the number of diagonal components gives its exact length.

25. Define eccentricity and curvature of boundary
     Eccentricity of boundary is the ratio of the major axis to minor axis.
     Curvature is the rate of change of slope.

26. Define shape numbers
    Shape number is defined as the first difference of smallest magnitude. The order n of
a shape number is the number of digits in its representation.

27. Describe Fourier descriptors
     Fourier descriptor of a boundary can be defined as
                         K-1
               a(u)=1/K∑s(k)e-j2Πuk/K
                         k=0

        for u=0,1,2……K-1.The complex coefficients a(u) are called Fourier descriptor
of a boundary.
 The inverse Fourier descriptor is
                    K-1
               s(k)= ∑ a(u)ej2Πuk/K
                     u=0
             for k=0,1,2,……K-1

28. Give the Fourier descriptors for the following transformations
       (1)Identity (2)Rotation (3)Translation (4)Scaling (5)Starting point

          (1)Identity – a(u)
          (2)Rotation -ar(u)= a(u)ejθ
          (3) Translation-at(u)=a(u)+ xyδ(u)
          (4)Scaling-as(u)=αa(u)
          (5)Starting point-ap(u)=a(u)e-j2Πuk0/K

29. Specify the types of regional descriptors
           • Simple descriptors
           • Texture




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30. Name few measures used as simple descriptors in region descriptors
             • Area
             • Perimeter
             • Compactness
             • Mean and median of gray levels
             • Minimum and maximum of gray levels
             • Number of pixels with values above and below mean
             •
31. Define compactness
             Compactness of a region is defined as (perimeter)^2/area.It is a
dimensionless quantity and is insensitive to uniform scale changes.

 32. Describe texture
               Texture is one of the regional descriptors. It provides measures of
properties such as smoothness, coarseness and regularity. There are 3 approaches used to
describe texture of a region.
               They are:
                        • Statistical
                        • Structural
                        • Spectral

33. Describe statistical approach
                 Statistical approaches describe smooth,coarse,grainy characteristics of
texture.This is the simplest one compared to others.It describes texture using statistical
moments of the gray-level histogram of an image or region.

34. Define gray-level co-occurrence matrix.
              A matrix C is formed by dividing every element of A by n(A is a k x k
matrix and n is the total number of point pairs in the image satisfying P(position
operator). The matrix C is called gray-level co-occurrence matrix if C depends on P,the
presence of given texture patterns may be detected by choosing an appropriate position
operator.

35. Explain structural and spectral approach
        Structural approach deals with the arrangement of image primitives such as
description of texture based on regularly spaced parallel lines.
       Spectral approach is based on properties of the Fourier spectrum and are primarily
to detect global periodicity in an image by identifying high energy, narrow peaks in
spectrum.There are 3 features of Fourier spectrum that are useful for texture description.
They are:
         • Prominent peaks in spectrum gives the principal direction of texture patterns.
         • The location of peaks in frequency plane gives fundamental spatial period of
             patterns.
         • Eliminating any periodic components by our filtering leaves non- periodic
             image elements.




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                                     16 MARKS

                                        UNIT I


1. Explain the steps involved in digital image processing.
                             (or)
   Explain various functional block of digital image processing
                       # Image acquisition
                      # Preprocessing
                      # Segmentation
                      # Representation and Description
                      # Recognition and Interpretation

2. Describe the elements of visual perception.
                     # Cornea and Sclera
                     # Choroid – Iris diaphragm and Ciliary body
                     # Retina- Cones and Rods

3. Describe image formation in the eye with brightness adaptation and
discrimination
                      # Brightness adaptation
                     # Subjective brightness
                     # Weber ratio
                     #Mach band effect
                     #simultaneous contrast

4. Write short notes on sampling and quantization.
                      # Sampling
                      # Quantization
                      # Representing Digital Images

5. Describe the functions of elements of digital image processing system
    with a diagram.
                      # Acquisition
                      # Storage
                      # Processing
                      # Communication
                      # Display

6. Explain the basic relationships between pixels?
                      # Neighbors of a pixel
                      # Connectivity, Adjacency, Path
                      # Distance Measure
                      # Arithmetic and Logic Operations




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7. Explain the properties of 2D Fourier Transform.
                       # Separability
                       # Translation
                       # Periodicity and Conjugate Symmetry
                       # Rotation
                       # Distribution and Scaling
                       # Average Value
                       # Laplacian
                       # Convolution and correlation
                       # Sampling
8. ( i )Explain convolution property in 2D fourier transform.
                       * 1D Continuous
                       * 1D Discrete
                       * 1D convolution theorem
                       * 2D continuous
                       * 2D Discrete
                       * 2D convolution theorem
     (ii) Find F (u) and |F (u)|




9. Explain Fast Fourier Transform (FFT) in detail.
                     # FFT Algorithm
                     # FFT Implementation

10. Explain in detail the different separable transforms
                       # Forward 1D DFT & 2D DFT
                       # Inverse 1D DFT & 2D DFT
                       # Properties

11. Explain Hadamard transformation in detail.
                   # 1D DHT
                   # 1D Inverse DHT
                   # 2D DHT
                   # 2D Inverse DHT

12. Discuss the properties and applications of
 1)Hadamard transform              2)Hotelling transform




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                       # Properties of hadamard:
                           Real and orthogonal
                           fast transform
                           faster than sine transform
                           Good energy compaction for image
                       # Appl:
                              Image data compression,
                              filtering and design of course
                       # Properties of hotelling:
                               Real and orthogonal
                              Not a fast transform
                              Best energy compaction for image
                       # Appl:
                       Useful in performance evaluation & for finding performance
bounds

   13. Explain Haar transform in detail.
                    # Def P= 2P+q-1
                    # Find h k (z)

   14. Explain K-L transform in detail.

         Consider a set of n or multi-dimensional discrete signal represented as column
         vector x1,x2,…xn each having M elements,

               X1
               X2
   X=             .
                .
               Xn

   The mean vector is defined as Mx=E{x}
   Where E{x} is the expected value of x.     M
   For M vector samples mean vector is Mx=1/M ∑ Xk
                                              K=1
                                                T
      The co-variant matrix is, Cx=E{(X-Mx)(X-Mx)}

                            M              T
         For M samples, Cx=1/M ∑ (xk-Mx)(xk-Mx).
                            K=1
         K-L Transform Y= A (X- MX)




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                                        UNIT II


1. Explain the types of gray level transformation used for image enhancement.
              # Linear (Negative and Identity)
              # Logarithmic( Log and Inverse Log)
              # Power_law (nth root and nth power)
              # Piecewise_linear (Constrast Stretching, Gray level Slicing,
                                   Bit plane Slicing)


2. What is histogram? Explain histogram equalization.
               # P(rk) = nk/n
               # Ps(s) = 1 means histogram is arranged uniformly.

3. Discuss the image smoothing filter with its model in the spatial domain.
               # LPF-blurring
               # Median filter – noise reduction & for sharpening image

4. What are image sharpening filters. Explain the various types of it.
              # used for highlighting fine details
              # HPF-output gets sharpen and background becomes darker
              # High boost- output gets sharpen but background remains unchanged
              # Derivative- First and Second order derivatives
       Appl:
              # Medical image
              # electronic printing
              # industrial inspection


5. Explain spatial filtering in image enhancement.
              # Basics
              # Smoothing filters
              # Sharpening filters

6. Explain image enhancement in the frequency domain.
              # Smoothing filters
              # Sharpening filters
              # Homomorphic filtering

7. Explain Homomorphic filtering in detail.
             # f(x, y) = i(x, y) . r(x, y)
             # Calculate the enhanced image g(x,y)




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                                  UNIT III



1. Explain the algebra approach in image restoration.
         # Unconstrained
         # Constrained

2. What is the use of wiener filter in image restoration. Explain.
         # Calculate f^
         # Calculate F^(u, v)

3. What is meant by Inverse filtering? Explain.
         # Recovering i/p from its o/p
         # Calculate f^(x, y)

4. Explain singular value decomposition and specify its properties.
         # U= m=1∑rψ√λm φmT
         This equation is called as singular value decomposition of an image.
         # Properties
         •The SVD transform varies drastically from image to image.
         •The SVD transform gives best energy packing efficiency for any given
         image.
         •The SVD transform is useful in the design of filters finding least
         square,minimum solution of linear equation and finding rank of large
         matrices.

5. Explain image degradation model /restoration process in detail.

           # Image degradation model /restoration process diagram
           # Degradation model for Continuous function
           # Degradation model for Discrete function – 1_D and 2_D

6. What are the two approaches for blind image restoration? Explain in detail.
          Direct measurement
          Indirect estimation




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                                 UNIT IV



1. What is data redundancy? Explain three basic data redundancy?
            Definition of data redundancy
             The 3 basic data redundancy are
                  Coding redundancy
                  Interpixel redundancy
                  Psycho visual redundancy

2. What is image compression? Explain any four variable length coding
   compression schemes.
                    • Definition of image compression
                    • Variable Length Coding
                        * Huffman coding
                        * B2 Code
                        * Huffman shift
                        * Huffman Truncated
                        * Binary Shift
                        *Arithmetic coding

3. Explain about Image compression model?
                    • The source Encoder and Decoder
                    • The channel Encoder and Decoder

4. Explain about Error free Compression?
       a. Variable Length coding
               i. Huffman coding
              ii. Arithmetic coding
       b. LZW coding
       c. Bit Plane coding
       d. Lossless Predictive coding

5. Explain about Lossy compression?
                    • Lossy predictive coding
                    • Transform coding
                    • Wavelet coding

6. Explain the schematics of image compression standard JPEG.
                    • Lossy baseline coding system
                    • Extended coding system
                    • Lossless Independent coding system




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7. Explain how compression is achieved in transform coding and explain about DCT

                            Block diagram of encoder
                            decoder
                            Bit allocation
                            1D transform coding
                             2D transform coding, application
                            1D,2D DCT

8. Explain arithmetic coding
                        Non-block code
                        One example

9. Explain about Image compression standards?
                          Binary Image compression standards
                          Continuous tone still Image compression standards
                          Video compression standards

10. Discuss about MPEG standard and compare with JPEG
              Motion Picture Experts Group
                  1. MPEG-1
                  2. MPEG-2
                  3. MPEG-4
              Block diagram
                      I-frame
                     p-frame
                     B-frame




                                        UNIT V


1. What is image segmentation. Explain in detail.
                       • Definition - image segmentation
                       • Discontinity – Point, Line, Edge
                       • Similarity – Thresholding, Region Growing, Splitting and
                           merging

2. Explain Edge Detection in details?
             * Basic formation.
             * Gradient Operators
             * Laplacian Operators




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3. Define Thresholding and explain the various methods of thresholding in detail?
              • Foundation
              • The role of illumination
              • Basic adaptive thresholding
              • Basic adaptive thresholding
              • Optimal global & adaptive thresholding.

4. Discuss about region based image segmentation techniques. Compare
      threshold region based techniques.
              * Region Growing
              * Region splitting and merging
              * Comparison

5. Define and explain the various representation approaches?
              • chain codes
              • Polygon approximations
              • Signature
              • Boundary segments
              • Skeletons.

6. Explain Boundary descriptors.
       • Simple descriptors.
       • Fourier descriptors.

7. Explain regional descriptors
       • Simple descriptors
       • Texture
                   i. Statistical approach
                  ii. Structural approach
                 iii. Spectral approach

8. Explain the two techniques of region representation.
              Chain codes
              Polygonol approximation

9. Explain the segmentation techniques that are based on finding the regions
directly.
              Edge detection line detection
               Region growing
               Region splitting
               region merging
10. How is line detected? Explain through the operators
              Types of line masks
                  1. horizontal
                  2. vertical
                  3. +45˚,-45˚


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MICROWAVE


ENGINEERING




              38
DEPARTMENT OF ELECTRONICS AND COMMUNICATION ENGINEERING
                          EC1403 MICROWAVE ENGINEERING
                     TWO MARK QUESTIONS AND ANSWERS



    1. Define s-matrix
            In a microwave junction there is intersection of three or more
components.There will be an output port ,in addition there may be reflection from the
junction of other ports.Totally there may be many combinations,these are represented
easily using a matrix called S matrix.

2What are the .Properties of s-matrix?
     1.It possess symmetric property sij =sji
      2.It possess unitary property
           [s][s]*=[i]
 3.Why is s-matrix used in MW analysis?
       S matrix is used in MW analysis to overcome the problems which occurs when
H,Y,&Z parameters are used in high frequencies.
             1.Equipment is not readily available to measure total voltage &total current at
the ports of the network.
             2.Short and open circuits are difficult to achieve over a broad band of
frequencies.
             3.Active devices,such as power transistor &tunnel diodes,frequently won’t
have stability for a short or open circuit.
  4.Give ABCD matrix for a two port network
             V1=A B V2
              I1 C D -I2
   5.What is ABCD matrix?
           ABCD matrix is a transmission matrix.these parameters express voltage and
current at output in terms of those at input port.
                       V1=AV2-BI2
                        I1=CV2-DI2
   6.What are the advantages of ABCD matrix?
          1.They are used in power transmission lines.
          2.They are very helpful in the case of cascade networks.
    7.What is the Scattering matrix for N port device?
           [S]= S11 S12 S13…… S1n
                  S21 S22 …………S2n
                  S31 S32 ………….S3n
                  .     .

                .     .
                .      .



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                   Sm1 Sm2 ………...Smm
      8.Give the S matrix of uniform transmission line
                       S= 0       e-jbl
                             -jbl
                           e       0
        9.Give the properties of impedence [x]&admittance[y] matrix?
             1.For a lossless junctionary y and z are symmetric .
             2.[y]=[z] -1
             3.Elements of matix [Z] &matrix [Y] are Frequency dependent.
        10.For a loss less junction all the elements in the impedence &admittance matrices
are
                                     Pure imaginary
     11.What are the properties of scattering matrix for a lossless junctoion?
            1.The product of any column of the S-matrix with conjugate of this column
equals unity.
            2.The product of any column of the scattering matrix with the complex
conjugate of any
               other column is zero.
      12.What is transmission matrix?
              When a number of microwave devices are connected in cascade.Each
junction is represented by a transmission matrix which gives the output quantities
interms of input quantities.
      13.Define one port circuit.Give two examples.
              A one port circuit is a circuit for which power can enter or leave through a
single wave
              Guide or transmission line.
             Examples:
             1.Short-circuited co-axial line
       14.Write the voltage matrix for an N-port microwave circuits.
              V1           Z11 Z12 ….. Z1N                I1
              V2            Z12 Z22 …… Z2N                I2
               .       =     .      .      …… ….          .
               .
               VN           ZN1 ZN2         .      ZNN IN
           Where Zij=Elements of impedence matrix.
                    [Z]=Impedence martrix
       15.For reciprocal media,the impedence and admittance matrices are
                            Symmetrical
       16.For non-reciprocal media,the impedence and admittance matrices are
                              Ans: Asymmetrical
       17.Give two examples for two port junctions.
             1.The junction of two rectangular guides of unequal height
             2.A symmetrical junction consisting of two similar rectangular guides joined
by an
               Intermediate guide of greater width.
      18.State the unique property of Scattering matrix?




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               Unitary Property: the row of a scattering matrix multiplied by the
complex conjugate of the same row of the scattering matrix is one.
19. Write the scattering matrix for a ideal waveguide section?
               [S]=[0 1
                      1 0]
20. What are the various reasons pertaining to the wide use of microwaves
       Bandwidth,Improved directivity with an Aerial array ,Reliability, Power
requirement.

21. What are the two types of terminations.
      Matched load
      Variable short circuit

22. What are ferrites and give its properties?
       Ferrites are ceramic like materials. These are maby by sintering a mixture of
metallic oxides
Properties
Specific resistivitieis may be used as much as 1014 greater than that of metals
Dielectric constants around 10to 15 or greater
Relative permeability is 1000

23.Give some examples of ferrite devices?
       Isolator Circulator Phaseshifters, Modulators, Power limiters

24. List two microwave devices using faraday rotation principles
        Isolator, Circulator
25.What are powere dividers?
        Power dividers are used to divide the input power into a number of smaller
amounts of power for exciting the radiating elements in an array antenna




      26.What is the S-matrix of 3 port circulators?
             Anticlockwise           [S]= 0 1 0
                                             0 0 1
                                             1 0 0

                  Clockwise            [S]= 0 0 1
                                             1 0 0
                                             0 1 0
      27. Give the differences between Isolator and Circulator




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Si.no Isolator                     Circulator

1      It is a 2 port device       It is a 3 port device
2      It cannot be used as        It is used as isolator by
       circulator                  terminating one port
3      If input is given in port   Each terminal is connected only
       1,output is obtained at     to the next terminal
       port 2 and vice versa
                                                                          28.What is
                                                                     the S-matrix for 4
                                                                     port circulators?
             Clockwise
           [S]= 0 0 0 1
                 1 0 0 0
                 0 1 0 0
                 0 0 1 0
             Anticlockwise
           [S] = 0 1 0 0
                  0 0 1 0
                  0 0 0 1
                  0 0 1 0
    29.Give the S-matrix of E-plane Tee.
           [S] = 0.5 0.5 0.707
                 0.5 0.5 -0.707
                 0.5 -0.707 0
    30.Give the S-matrix of H-plane Tee
          [S] = 0.5 -0.5 0.707
                 -0.5 0.5 0.707
                 0.707 0.707 0

    31.Give the S-matrix of Magic Tee

           [S] = 0 0 0.707 0.707
                 0 0 0.707 -0.707
                0.707 0.707 0   0
                0.707 -0.707 0  0

    32.Give the Smatrix of directional coupler
          [S] = 0 P 0 jq
                 P 0 jq 0
                 0 jq 0 P
                 Jq 0 P 0



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    33.Give an example for a two port MW device
         Isolator is an example for a 2 port MW device

    34.Give the applications of directional coupler
        1.Unidirectional power measurement
        2.SWR measurement
        3.Unidirectional wave launching
        4.Reflectometer
        5.Balanced duplexer

    35.What is Faraday’s rotation law?
         If a circulary polarised wave is made to pass through a ferrite rod which has
been influenced by an axial magnetic field B ,then the axis of polarization gets tilted in
clockwise direction and amount of tilt depends upon the strength of magnetic field and
geometry of the ferrite.

   36.Define VSWR
       Voltage standing wave ratio is defined as the ratio of maximum voltage to the
minimum vottage
                           VSWR=Vmax/Vmin

    37.What is Gyrator?
         Gyrator is a two port device which provides a relative phase shift of 180 degree
for transmission from port 1 to port 2 as compared to the phase for transmission from
         Port2 to port 1.

    38.What is the principle of Microwave phase shifter?
        When a wave propagates on a line,a phase difference prevails between any two
arbitary points along its paths.The phase difference between two points,

  39.what are junctions?Give some examples
        A microwave circuit consists of several microwave devices connected in some
way to achieve the desired transmission of MW signal.The interconnection of two or
more microwave may be regarded as MW junction.
        Eg:Magic Tee,Hybrid Ring

    40.What is Tee junction?Give two examples
         In MW circuits a wave guide or coaxial junction with three independent ports is
referred to as tee junction.
           Eg: E- Plane Tee,H-plane Tee

   41.What is the other name for magic TEE?
       Hybrid Tee

   42.What is hybrid ring?



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         Hybrid ring consists of an annular line of proper electrical length to sustain
standing waves,to which four arms are connected at proper intervals by means of series
or parallel junctions.

  43.What is the other name for Hybrid ring?
      Rat-race circuit.


   44.Name some wave guide components used to change the direction of the guide
through an arbitrary angle
      Wave guide corner,Bend and twist

   45.What are the different types of Directional coupler?
      1.Two hole directional coupler
      2.Be the hole directional coupler
      3.Four hole directional coupler

   46.What are hybrid couplers?
        Hybrid couplers are interdigitated microstrip couplers consisting of four parallel
striplines with alternate lines tied together,It has four ports.This type of coupler is called
Lange hybrid coupler.

47. What are nonreciprocal devices? Give two examples
        The devices which are having the property that the forward characteristics are not
equal to the reverse characteristics are called non reciprocal devices.

48.Why isolators are called uniline?
        An ideal isolator completely absorbs the power for propagation in one direction
and provides lossless transmission in the opposite direction. Thus isolators are called
uniline

49. Give some coupling parameters of directional coupler?
       Coupling coefficient, Directivity, Insertion loss, Isolation

50.      What are the high frequency effects in conventional tubes?
         The high frequency effects in conventional tubes are
      i) Circuit reactance
         a)Inter electrode capacitance
         b) Lead inductance
      ii) Transit time effect
      iii) Cathode emission
      iv) Plate heat dissipation area




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      v) Power loss due to skin effect, radiation and dielectric loss.


51.      What are the assumptions for calculation of RF power in Reflex Klystron?
         i)      Cavity grids and repeller are plane parallel and very large in extent.
         ii)     No RF field is excited in repeller space
         iii)    Electrons are not intercepted by the cavity anode grid.
         iv)     No debunching takes place in repeller space.
         v)      The cavity RF gap voltage amplitude V, is small compared to the dc beam
                 voltage VO


52.      What is the condition for oscillation in Reflex klystron ?
         The necessary condition for oscillation is that the magnitude of the negative real
part of the electronic admittance should not be less than the total conductance of the
cavity circuit i.e. │-Ge│≥G.
Where                            1
         G=Gc + Gb +G1 = ------
                              Rsh
Rsh      →       effective shunt resistance
Gc       →       copper losses of cavity
Gb       →       beam loading conductance
G1       →       load conductance




53.      Give the drawbacks of klystron amplifiers.
         1.      As the oscillator frequency changes then resonator frequency also changes
and the feedback path phase shift must be readjusted for a positive feedback.




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        2.     The multicavity klystron amplifiers suffer from the noise caused because
bunching is never complete and electrons arrive at random at catcher cavity. Hence it is
not used in receivers.


54.     What is the effect of transit time?
        There are two effects.
        1)     At low frequencies, the grid and anode signals are no longer 180O out of
               phase, thus causing design problems with feedback in oscillators.
       2)      The grid begins to take power from the driving source and the power is
               absorbed even when the grid is negatively biased.


55.    What are the applications of reflex klystron ?
       1)      Signal source in MW generator
       2)      Local oscillators in receivers
       3)      It is used in FM oscillator in low power MW links.
      4)       In parametric amplifier as pump source.


56.    What is the purpose of slow wave structures used in TWT amplifiers?
       Slow wave structures are special circuits that are used in microwave tubes to
reduce wave velocity in a certain direction so that the electron beam and the signal wave
can interact. In TWT, since the beam can be accelerated only to velocities that are about
a fraction of the velocity of light, slow wave structures are used.




57.    How are spurious oscillations generated in TWT amplifier? State the method to
suppress it.
       In a TWT, adjacent turns of the helix are so close to each other and hence
oscillations are likely to occur.     To prevent these spurious signals some form of
attenuator is placed near the input end of the tube which absorb the oscillations.




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58.      State the applications of TWT.
         1)         Low power, low noise TWT’s used in radar and microwave receivers
         2)         Laboratory instruments
         3)         Drivers for more powerful tubes
         4)         Medium and high power CWTWT’S are used for communication and
radar.


       59.How the klystron amplifier can act as klystron oscillator? What are the
       applications of klystron amplifier?
         When the klystron amplifier is given a positive feedback such that the overall
phase shift becomes zero 360˚ and │βAv │= I then klystron amplifier acts as an
oscillator.
Applications:
          (1) UHF TV Transmitters
         (2) Long ranger radar
         (3) Linear particle accelerator
         (4) Troposcatter links
         (5) Earth station transmitter.
       60.Define phase focusing effect.
                           The bunching of electrons in known as “ Phase focusing effect”
      This effect is important because without it, favoured electrons will fall behind the
      phase change of electric field across the gaps. Such electrons are retarded at each
      interaction with the R.F field in magnetron.


       61.What do you mean by O-type tubes? Name some O-type tubes.
              In O – type tube a magnetic field whose axis coincides with that electron
              beam is used to hold the beam together as it travels the length of the tube. It is
              also called as linear beam tube.
              i)       Helix Traveling wave tube
              ii)      Coupled cavity TWT



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            iii)      Forward wave amplifier
            iv)       Backward wave amplifier
            v)        Backward wave oscillator




      62. Define Transit time in Reflex klystron.
                   The time taken by the electron to travel into the repeller space and back to
     the gap.
                          T =n + ¾


      63. Write the parameters on which bunching depend on?
            vi)       Drift space should be properly adjusted.
            vii)      D.C anode voltage
            viii)     Signal amplitude should be such that proper bunching takes place.


      64. Compare TWTA Klystron amplifier


       Klystron amplifier                                                  TWTA


1.      Linear beam or ‘O’ type device.                         Linear beam or ‘O’ type device


2.      Uses cavities for input and                    Use non resonant wave circuit.
        Output circuits.
3.      Narrow band device due to                       Wide band device because use of use of
     resonant cavities.                       Non-resonant wave circuit.




      65. Give the performance Specification of Reflex klystron?



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           Frequency range:       2- 200 GHz
           Band width:            + 30 MHz for ∆ VR = + 10 V
           Power output: 10 mw – 2.5W
           Efficiency:            20 to 30%




 66. What is CFA? State the applications of CFA.
           CFA →Cross Field Amplifier
           CFA is a microwave power amplifier. It is a cross between TWT and
magnetron in its operation. i.e., it has a magnetron structure to provide an interaction
between crossed dc electric and magnetic fields on one hand and an RF field on the
other hand. It also uses a slow wave structure as in TWT to provide a continuous
interaction between the electron beam and a moving RF field.
Applications:
(1) Radar system
(2) Electronic counter measure.


 67. State the characteristics of magnetron and of 2-cavity klystron amplifier.
    Magnetron:
           Operating frequencies → 70 GH z
           Output power       → 40 MW
           Efficiency              → 40 to 70%
       2-cavity klystron:



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              Efficiency          → 40%
              Power output        → average power ═> 500 KW
              Pulsed power ═> 30 MW
              Power gain       → about 30 db.


     68. What are the advantages of TWT?


              1.      Bandwidth is large.
              2.      High reliability
              3.      High gain
              4.      Constant Performance in space
              5.      Higher duty cycle.




     69. What is meant by strapping?
              The magnetron has eight or more coupled cavity resonators and hence
              several modes of oscillation are possible. The oscillating frequency of
              different modes are not same and are quite close to each other which
              results in mode jumping. i.e., a 3 cm π mode oscillation which is normal
              for a particular magnetron
                                      3π
              Could become a 3.05 cm------- mode oscillation. This result in
                                          4

               oscillations of reduced power at wrong frequency. To prevent this.
Strapping is used. It consists of two rings of heavy gauge wire connecting alternate
anode poles. It provides a phase difference 0f 2 π radians for the modes other π-mode
and thus preventing the occurrence of other modes, except the π-mode .


     70. State the applications of magnetrons. why magnetron is called as cross filed
     device?



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   1)    Pulse work in radar
   2)    Linear particle accelerators.
   In cavity magnetron, there exists a radial electric field and an axial magnetic field
   perpendicular to each other and hence magnetron is called as a cross filed device.

     71. What is BWO? State the applications of BWO.

                A backward wave oscillator (BWO) is microwave cw oscillator with an
                enormous tuning and ever all frequency coverage range.
                Applications:
           (i)     It can be used as signal source in instruments and transmitters.
           (ii)    It can be used as broad band noise sources which used to confuse
                   enemy radar.

     72. What is hull cutoff condition?

               In a magnetron, the electron will just graze the anode and return towards
               the cathode depends on Vo and Bo . The hull cut of magnetic equation is
                       Boc = (8Vo m / e) ½
                               -------------
                                b(1- a 2 / b2 )
               The hull cutoff voltage equation is
                       Voc = e BO2 b2 (1- a2/ b2 )
                           …….

                                8m
                If B0>BOe for given Vo.the electrons will not reach anode.
If Vo < Voc for a given Bo the electrons will not reach the anode.



73. What are the principal limitations of conventional negative grid electron tubes?

 1) Electron transit time becomes a noticeable proportion at high frequencies.
 2) Lumped electrical reactance and low Q resonant circuit.


74. What is frequency pulling and frequency pushing in magnetrons?

        Frequency pulling is caused by changes in the load impedance reflected into the
cavity resonators. Frequency pushing is due to the change in anode voltage which alters
the orbital velocity of electron clouds.

75.What are the applications of High Q-oscillators and amplifier circuits?
    They are used in
         a)Low power transmitters



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           b)Parametric amplifier pumps
           c)Police radars and intrusion alarms.

76.What are the Key phenomenon taking place in TRAPATT diode?
      The Key phenomena are
           a)Carrier generation by impact ionization producing a current pulse of phase
delay of 90 degree.
            b)An additional phase shift introduced by the drift of carriers.

77.What is the operating frequency of TRAPATT devices?
     TRAPATT devices operate at frequencies from 400 MHz to about 12GHz.

78. What are the applications of TRAPATT devices?
       The applications are
          a)Phased-array Radar systems
          b)Intermediate frequency transmitters.
          c)Proxity fuse sources
          d)Radio altimeters
           e)Microwave landing systems.

79. What are the applications of Tunnel Diode?
        a)used in self excited mixers
        b)High speed switching and logic operations
        c)Low power oscillators.

80.What are the elements that exhibit Gunn effect?
       The elements are
         a)Gallium arsenide
         b)Indium phosphide
         c)Cadmium telluride
         d)Indium arsenide.

81. What are the applications of Gunn Diode?
      The applications are
         a) Low and medium power oscillators
         b) Used in high pump frequencies
         c) Burglar alarms and aircraft rate-of-climb indicators.



82.What is negative resistance?
        Negative resistance is defined as that property of a device which causes the
current through it to be 180 degree out of phase with the voltage across it.




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83.What are the applications of Backward diode?
             a) Video detection
             b) Doppler radar

84. Why are FET’s preferred to bipolar transistor at high frequencies?
                 FET’s are preferred over Bipolar transistors at high frequencies as they
    easily lend themselves more readily to intrgration.

85.What is the main advantage of TRAPATT over IMPATT?
              TRAPATT diode has much greater efficiency than IMPATT.

86.Draw the schematic diagram of PIN diode?

                           1. Metallic contact
                   ii. -------------------------------------------------------
                            1. n-type Si
                  iii. -----------------------------------------------------
                  iv. Intrinsic Si
                   v. (Slightly n-doped)


                  vi. ---------------------------------------------------
                           1. p-type Si
                 vii. ------------------------------------------------------
                           1. Mettalic contact

87. Define GUNN EFFECT.
           Guneffect was first observed by GUNN in n_type GaAs bulk diode.according
           to GUNN,above some critical voltage corresponding to an electric field of
           2000-4000v/cm,the current in every specimen became a fluctuating fuction of
           time.The frequency of oscillation was determined mainly by the specimen and
           not by the external circuit.

88. What is MESFET?
          If the field effect transistor is constructed with metal semiconductor schottky
          barrier diode,the device is called metal-semiconductor field effect transistor.




89.Explain stable amplification mode.
                   When ‘n0l’product of the device is less than about 10 ^(12)/cm^2 the
                   device exhibits amplification at transit time frequency rather than




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                spontaneous oscillation. This is called stable amplification
                mode.Here n0 is the amount of doping and ‘L’ is the length.


90.What are the factors reducing efficiency of IMPATT diode?
               1)Space charge effect
               2)Reverse saturation current effect
               3)High frequency skin effect
               4)Ionization saturation effect.

91.Explain plasma formation in TRAPATT diode.
      During the operation of the diode a high field avalanche zone propagates
      through the depletion region and fills the layer with a dense plasma of
      electrons and holes which get trapped in the low field region behind the zone.

92.What is negative resistance in gunn diode?
               The carrier drift velocity increases linearly from 0 to maximum
               when the electric field is increased from 0 to threshold value in
               gunndiodes.When the electric field is beyond the threshold value of
               3000v/cm the drift velocity is decreased and the diode exhibit
               negative resistance.

93.What are the applications of GaAsMESFET.?
               a,Used in microwave integrated circuits for high power, low noise
               applications.
               b.Used in broadband amplifier application.

94.What are the applications of TRAPATT?
         a)Used in airborne
         b)Marine radars.

95.What is Transferred electron effect?
               Some materials like GaAs exhibit negative differential
               mobility,when biased above a threshold value of the electric
               field.This behaviour is called transferred electron effect.

96.What are time parameter for TED’S
         a)Domain growth time constant
         b)Dielectric relaxation time
         c)transit time.




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97.What are the various modes of transferred electron oscillators?
         a)Transit time mode
         b)Quenched and delayed domain modes
         c)limited space charge accumulation mode.

98.List the type of circuit used for IMPATT diode circuits.
       a)Broadly tunable circuits
       b)Low ‘Q’circuits
       c)high ‘Q’circuits

99.What are the applications of low Q-oscillators and amplifier circuits?
     a)Final output stage of FM telecommunication transmitter
     b)Up converter pump
     c)CW Doppler radar transmitter.


100.List some of power detecting elements?
                1.Schottky diode
                2.baretter
                3.thermistor
                4.thermocouple
101.What are microwave detector?
                Microwave detectors are the instruments used to detect the
presence of microwave power is a microwave circuit.

102.Differentiate baretter and thermistor?
Baretter
1.baretter has positive
temperature coefficient.
2.it has thin wire.
3.less sensitive.
4.required less bias current

Thermistor
1.negative temp coefficient.
2.small bead of semi conductor material.
3.more sensitive.
4.require more sensitive.

103.What are tunable detector?
     The tunable detectors are used to demodulate the signal and couple the
     required output to high frequency scope analyzer.The low frequency
     demodulated output is detected using non reciprocal detector diode monunted
     in the microwave transmission line.




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104. What is slotted section with line carriage?
It is a microwave sectioned coaxial line connecting a coaxial E-field probe which
penetrates inside a rectangular waveguide slotted section.The longitudinal slot is cut
along the center of the waveguide broad walls.The probe is made to move along the
slotted wall which samples the electric field propotional to probe voltage.

105. What is the main purpose of slotted section with line carriage?
      1.For determination of location of voltage standing wave maxima and minima
      along the line.
      2.Measure the VSWR and standing wave pattern.
      3.Wavelength.
      4.Impedence.
      5.Reflection coeffient.
      6.Return loss measurement.
106. What is a VSWR meter?
                VSWR meter is a highly sensitive,high gain,high theta,low noise
                voltage amplifier tuned normally at fixed frequency of 1KHZ of
                which microwave signals modulated.This meter indicates calibrated
                VSWR reading fir any loads.


107. What is Bolometer?
               It is a power sensor whose resistance change with changed
               temperature as it absorb the microwave power.It is ashort thin
               metallic wire sensor with positive temperature coefficient of
               resistance.

108. What is calorimeter?
It is convenient device setup for measuring the high power at microwave which
involves conversion of microwave energy in to heat,absorbing the heat in a f luid
and determine the temp.

109.Mention the disadvantages of single bridge circuit ?
1.change in resistance due to mismatch at the microwave input port results in
incorrect reading
2.the thermistor is sensitive to change in the ambient temp resulting in false
readings

110. Define insertion loss?
It is defined as difference in power arriving at the terminating load .with or witout
The network in circuit
                 Insertion loss(db)=10 log(po/pi)

111.How will you determine the vswr and return loss in reflecto meter method?
The voltage ratio between port3 or port4 is known reflectin coefficient (T) determined
we determine VSWR and return loss as



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                        VSWR=(1+T)/(1-T)
                        Return loss=-20 log(T)
112.List the different types of Impedence measurement methods?
                 1.Slotted line method
                 2.Reflectometer method
                 3.Reactor discontructer method
113.How do you measure microwave frequency?
                 1.Wavemeter method
                 2.Slotted line method
                 3.Downconversion method
114.What is a wavemeter?
                 It is a device used for frequency measurement in microwave.It has
                 cylindrical cavity with a variable short circuit termination .It changes
                 the resonant frequency of cavity by changing cavitylength.
115.Define dielectric constant?
                 It is defined by the ratio of permittivity of medium to permittivity of
                 freespace.
                        ξr=ξ/ξo=((10^-9)/36π)
116.How the S-parameter of a microwave circuit measured?
                 S-parameters are conveniently measured using the deschamps
                 method which utilizes the measured value of complex input
                 reflection coefficient under a number of a reactive terminations.




117. List the methods for measuring dielectric constants?
       1.Waveguide method
                 2.cavity pertubaration method
118.What is radiation pattern?
    Radiation pattern is a representation of radiation characteristics of an antenna
which is a function of elevation angle azimuth angle for a constant radial distance and
frequency.

119. What is radiation efficiency?
Radiation efficiency is defined as the ratio of total power radiated to total power
accepted at its input .


120. How do you measure the polarization?
    The polarization of an antenna is measured using transmitting mode and probing
the polarization by a dipole antenna in the which the dipole is rotated in the plane of
polarization and the received voltage pattern is recorded.




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121. What is spectrum analyzer?
    Spectrum analyzer is a broad band super heterodyne receiver which is used to
display a wave in frequency domain additionally, power measurements, side bands
can also be observed.

122.List the types of spectrum analyzer
   Real time spectrum analyzer
   Swept tuned frequency spectrum analyzer

123. List some application of spectrum analyzer.
   Identifying frequency terms and their power levels
   Measuring harmonic distortion in a wave
   Determine type of wave modulation
   Signal to noise ratio
   For identifying wave distortion

124. What is network analyzer
       A Network analyzer measures both amplitude and phase of a signal over a
wide frequency range. It requires accurate reference signal and a test signal




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                                    16 mark questions

1.Explain in detail about 2-cavity klystron amplifier.

-schematic circuit diagram
-mechanism of operation
-velocity modulation process
-bunching process
-calculation of efficiency, mutual conductance and voltage gain.

2. Explain about the reflex klystron.

-schematic diagram
-velocity modulation process
-power output &efficiency
-frequency characteristics.
-electronic admittance of reflex klystron.

3. Explain about TWT amplifiers.

-principle of operation
-calculation of gain
-applications

4. Explain about magnetron oscillator.

-schematic diagram
-equations of electron trajectory
-cut off magnetic field &voltage
-resonant modes&mode separation
-mechanism of oscillation.

5. Numerical problems.
-calculation of output voltage, power,efficiency for 2-cavity klystron amplifier, reflex
klystron,magnetron,TWTamplifiers.


6.What are the properties of scattering matrix for a lossless junction?
           1.The product of any column of the S-matrix with conjugate of this column
equals unity.
           2.The product of any column of the scattering matrix with the complex
conjugate of any
              other column is zero.




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7.What are ferrites devices.Explain in detail the different ferrite devices
       Ferrites are ceramic like materials. These are maby by sintering a mixture of
metallic oxides
Properties
Specific resistivitieis may be used as much as 1014 greater than that of metals
Dielectric constants around 10to 15 or greater
Relative permeability is 1000
     some examples of ferrite devices are Isolator Circulator Phaseshifters, Modulators,
Power limiters

Circulator
    S-matrix of 3 port circulators
               Anticlockwise            [S]=     0 1 0
                                                0 0 1
                                                1 0 0

                  Clockwise               [S]= 0 0 1
                                               1 0 0
                                               0 1 0
      S-matrix for 4 port circulators
             Clockwise
           [S]= 0 0 0 1
                  1 0 0 0
                  0 1 0 0
                  0 0 1 0
             Anticlockwise
           [S] = 0 1 0 0
                   0 0 1 0
                   0 0 0 1
                   0 0 1 0

8. Dicuss the high frequency effects in conventional tubes?
       The high frequency effects in conventional tubes are
    i) Circuit reactance
       a)Inter electrode capacitance
       b) Lead inductance
     ii) Transit time effect
    iii) Cathode emission
    iv) Plate heat dissipation area
    v) Power loss due to skin effect, radiation and dielectric loss.




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9.Explain in detail about spectrum analyzer?
    Spectrum analyzer is a broad band super heterodyne receiver which is used to
display a wave in frequency domain additionally, power measurements, side bands
can also be observed.
 Types of spectrum analyzer
    Real time spectrum analyzer
    Swept tuned frequency spectrum analyzer
Application of spectrum analyzer.
    Identifying frequency terms and their power levels
    Measuring harmonic distortion in a wave
    Determine type of wave modulation
    Signal to noise ratio
    For identifying wave distortion

10.Explain in detail about network analyzer
       A Network analyzer measures both amplitude and phase of a signal over a
wide frequency range. It requires accurate reference signal and a test signal
   -Applications
   -Types

11.Explain the different types of Impedence measurement methods?
                1.Slotted line method
                2.Reflectometer method
                3.Reactor discontructer method

12. How do you measure microwave frequency?
               1.Wavemeter method
               2.Slotted line method
               3.Downconversion method

 Wavemeter is a device used for frequency measurement in microwave.It has
 cylindrical cavity with a variable short circuit termination .It changes the resonant
 frequency of cavity by changing cavitylength

13. Explain the power measuring devices baretter and thermistor?
Baretter
1.baretter has positive
temperature coefficient.
2.it has thin wire.
3.less sensitive.
4.required less bias current

Thermistor
1.negative temp coefficient.
2.small bead of semi conductor material.
3.more sensitive.



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   4.require more sensitive.


   14.Explain in detail power detecting elements?
                   1.Schottky diode
                   2.baretter
                   3.thermistor
                   4.thermocouple

   15.Explain in detail about microwave detector?
                    Microwave detectors are the instruments used to detect the
   presence of microwave power is a microwave circuit.
   Types
       Crystal detector
       Tunable detector


   16.What is Transferred electron effect?Explian some of the TED’s?
                  Some materials like GaAs exhibit negative differential
                  mobility,when biased above a threshold value of the electric
                  field.This behaviour is called transferred electron effect.

              a)Domain growth time constant
              b)Dielectric relaxation time
              c)transit time.

   17.What is negative resistance in gunn diode?Desribe the operation of GUNN
   diode

           Guneffect was first observed by GUNN in n_type GaAs bulk diode.according
           to GUNN,above some critical voltage corresponding to an electric field of
           2000-4000v/cm,the current in every specimen became a fluctuating fuction of
           time.The frequency of oscillation was determined mainly by the specimen and
           not by the external circuit.

                      The carrier drift velocity increases linearly from 0 to maximum
           when the electric field is increased from 0 to threshold value in
           gunndiodes.When the electric field is beyond the threshold value of 3000v/cm
           the drift velocity is decreased and the diode exhibit negative resistance.


18.Explain the operation of TRAPATT diode
      The Key phenomena are
           a)Carrier generation by impact ionization producing a current pulse of phase
delay of 90 degree.
            b)An additional phase shift introduced by the drift of carriers.



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TRAPATT devices operate at frequencies from 400 MHz to about 12GHz.
 The applications are
    a)Phased-array Radar systems
    b)Intermediate frequency transmitters.
    c)Proxity fuse sources
    d)Radio altimeters
     e)Microwave landing systems.




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OPTICAL
COMMUNICATION




                64
                                          2 marks
   1. Write the expression for the refractive index in graded index fibers.
             n(r)= n1[1-2∆(r/a)α]1/2 for 0<=r<=a
                   n1(1-2∆)1/2 ~ n1(1-∆) =n2 for r>=a

                      r radial distance from fiber axis
                      a core radius
                      n1 refractive index at the core
                      n2 refractive index at the cladding
                      α shape of the index profile
                      ∆ index difference

    2. Define Numerical aperture of a step index fiber.
                  Numerical aperture (N.A) of the fiber is the light collecting efficiency
of the fiber and is the measure of the amount of light rays that can be accepted by the
fiber. It is equal to the sine of acceptance.
                   N.A=sin Φmax =(n12-n22)1/2
  where n1 and n2 are the refractive indices of core and cladding respectively.


   3. Define Mode-field diameter.
             The fundamental parameter of a single mode fiber is the mode-field
      diameter. This can be determined from the mode field distribution of the
      fundamental LPo1 mode.


   4. Give the expression for linearly polarized waves.
              The electric or magnetic field of a train of plane polarized waves
      travelling in a direction k can be represented in the general form
              A(x,t) = eiAoexp[j(wt-k.x)]
      with x=xex+yey+zez representing a general position vector and
      k=kxex+kyey+kzez representing the wave propagation vector.


  6.What is Snell’s law?
              The relationship at the interface is known as Snell’s law and is given by
                      n1sinΦ1=n2 sinΦ2


 7.What is the necessity of cladding for an optical fiber?
     a) To provide proper light guidance inside the core
     b) To avoid leakage of light from the fiber
     c) To avoid mechanical strength for the fiber
     d) To protect the core from scratches and other mechanical damages

8. What are the uses of optical fibers?



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       a) To transmit the information which are in the form of coded signals of the
telephone communication, computer data, etc.
       b) To transmit the optical images (Example : Endoscopy)
       c) To act as a light source at the inaccessible places.
       d) To act as sensors to do mechanical, electrical and magnetic measurements.

9. What is the principle used in the working of fibers as light guides?
           The phenomenon of total internal reflection is used to guide the light in the
optical fiber. To get total internal reflection, the ray should travel from denser to rarer
i.e. from core to clad region of the fiber and the angle of incidence in the denser
medium should be greater than the critical angle of that medium.


10. what are step index and graded index fibers?
          In the case of graded index fiber, the refractive index of a core is a constant
and is larger than the refractive index of the cladding. The light propagation is mainly
by meridional rays. In the case of graded index fiber (GRIN fiber) the refractive index
of the core varies parabolically from the centre of the core having maximum refractive
index to the core-cladding interface having constant minimum refractive index. Here
the light propagation is by skew rays.


11. Define acceptance angle.
       The maximum angle ‘Φmax’ with which a ray of light can enter through the
entrance end of the fiber and still be totally internally reflected is called acceptance
angle of the fiber.


12. Why do we prefer step index single mode fiber for long distance communication?
        Step index single mode fiber has a)low attenuation due to smaller core
    diameter b) higher bandwidth and c) very low dispersion.


13. Define relative refractive index difference.
        ∆ = n12-n22 = n1-n2
              2n12        n1
      Thus relative refractive index difference is the ratio between the refractive index
    difference (of core and cladding) and refractive index of core.


14. What are meridional rays?
        Meridional rays are the rays following Zig Zag path when they travel through
fiber and for every reflection it will cross the fiber axis.


15. What are skew rays?
          Skew rays are the rays following the helical path around the fiber axis when
they travel through the fiber and they would not cross the fiber axis at any time.

16. What is V number of fiber or normalized frequency of fiber?



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       V number of fiber or normalized frequency of fiber is used to find the number
of propagating modes through the fiber.
               V= 2∏a (N.A)
                    λ
          In step index fiber number of modes propagating through the fiber=V2
                                                                                2
Taking the two possible polarizations, total number of possible modes propagating
through the fiber = V2 * 2 = V2
                    2

 17. What are the conditions fro total internal reflection?
        a) Light should travel from denser medium to rarer medium.
         b) The angle of incidence should be greater than the critical angle of the
         denser medium.

 18.Give the relation between numerical aperture of skew rays and meridional rays.
         (N.A)skew = cos γ(N.A)meridional when the fiber is placed in air.
                 Here γ is the half of the angular change in every reflection.

 19. State Goos-Haenchen effect.
           Goos-Haenchen effect states that there is a lateral shift of the reflected ray
 at the point of incidence at the core-cladding interface. This lateral shift is called the
 Goos-Haenchen shift.


 20. When do you have phase shift during total internal reflection of light.
             When the light ray travels from denser medium to rarer medium, if the
 angle of incidence is greater than the critical angle of core medium, there is a phase
 shift for both TE and TM waves.


 21. What are hybrid modes? Give two examples.
         Hybrid modes are the mixture of TE and TM modes that can be traveled
 through the optical fiber.
  Examples:
         1. HE1m modes in which |Ez|>|Hz|
         2. EH1m modes in which |Hz|>|Ez|


 22. Define cutoff wavelength of the fiber.
           The cutoff wavelength is defined as the minimum value of wavelength that
 can be transmitted through the fiber. The wavelengths greater than the cutoff
 wavelength can be transmitted.
                    λ cutoff = 2∏a (N.A)
                                 V
 23. Mention the rule distinguishing ‘mode’ and ‘order’.
           The rule states that the smaller the modes propagating angle, the lower the
 order of the mode. Hus the mode traveling precisely along the fiber’s central axis is
 zero mode.




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 24.What is fiber birefringence?
          Imperfections in the fiber are common such as asymmetrical lateral stress,
 non circular imperfect variations of refractive index profile. These imperfections
 break the circular symmetry of ideal fiber and mode propagate with different phase
 velocity and the difference between their refractive index is called fiber birefringence.
                    B=ko(ny-nx)

25. Give the expression for numerical aperture in graded index fibers.
         N.A(r)=N.A.(0) (1-(r/a)α)1/2 for r<=a
      where N.A(0) = axial numerical aperture = (n12-n22)1/2
       a is core radius and α is the refractive index profile.

26.What is Intra Modal Dispersion?
           Intra Modal dispersion is pulse spreading that occurs with in a single mode.
   The spreading arises from finite spectral emission width of an optical source. This
   phenomenon is also called as group velocity dispersion.

  27.What are the causes of intra modal dispersion?
             There is two main causes of intra modal dispersion. They are:
         • Material dispersion
         • Wave guide dispersion

   28.What is material dispersion?
           Material dispersion arises from the variation of the refractive index of the
   core material as a function of wavelength. Material dispersion is also referred to as
   chromatic dispersion. This causes a wavelength dependence of group velocity of
   given mode. So it occurs because the index of refraction varies as a function of
   optical wavelength. Material dispersion is an intra modal dispersion effect and is for
   particular importance for single ode wave-guide.

   29.What is waveguide dispersion?
        Wave guide dispersion which occurs because of a single mode fiber confines
   only about 80% of optical power to the core. Dispersion this arises since 20% of
   light propagates in cladding travels faster than the light confined to the core.
   Amount of wave-guide dispersion depends on fiber design. Other factor for pulse
   spreading is inter modal delay

   30. What is group velocity?
           If L is the distance traveled by the pulse, β is the propagation constant along
   axis then the group velocity in the velocity at which energy is a pulse travels along
   the fiber.
                               Vg = C. (dβ / dk)

 31.What is group delay?
          In an optical fiber there are various modes present. Then the optical input,
  which is propagated along the fiber, will travel in various modes. Because of these
  modes the velocity of the signal will vary also there may be a delay in the optical
  signal of these various modes. This is called as the ‘ Group Delay’.




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   32.What is polarization?
       It is a fundamental property of an optical signal .It refers to the electric field
    orientation of a light signal which can vary significantly along the length of a fibre.

  33.What is pulse Broadening?
        Dispertion induced signal distortion is that a light pulse will broaden as it
travels along the fibre.This pulse broadening causes a pulse to overlap with
neighbouring pulses.After a time ‘t’,the adjacent pulses can no longer be individually
distinguished at the receiver and error will occur.


34.What is polarization Mode Dispersion(PMD)?
      The difference in propagation times between the two orthogonal polarization
modes will result in pulse spreading.This is called as polarization Mode Dispersion.

35.What is Mode Coupling?
        It is another type of pulse distorsion which is common in potical links.The pulse
distortion will increase less rapidly after a certain initial length of fibre due to this mode
coupling and differential mode losses.In initial length coupling of energy from one
mode to another arises because of structural irregularities,fibre dia. etc.

36.What is Profile Dispersion?
       A fibre with a given index profile(alpha) will exhibit different pulse spreading
according to the sourse wavelength used.This is called as Profile Dispersion.

37.What is M-C fiber?
    Fibers that have a uniform refractive index throughout the claddind is called as
M-C fiber or Matched-cladding fiber.

38.What is D-C fiber?
      In depressed cladding fiber the cladding portion next to the core has a lower
index than the outer cladding region.

39.Define depression shifted fiber
     by creating a fiber with large negative waveguide dispersion & assuming the
same values for material dispersion as in a standard single mode fiber the addition of
waveguide & material dispersion can then shifted to zero dispersion point to long
wavelenth. The resulting optical fiber are known as dispersioin shifted fiber.

40.Define dispersion flattening?
      The reduction of fiber dispersion by spreading the dispersion minimum out over
a widen range .this approach is known asd dispersion flattering.

 41.What is effective cut-off wavelenth?
       It is defined as the largest wavelenth at which the higher order LP11 mode power
relative to the fundamental LP01 mode power is redued to 0.1db. 2.what is intramodal
dispersion?
         The intramodal dispersion depends on wavelength and its effect on signal
distortion increases with the spectral width of the optical source.(It is a band of
wavelength over which the source emits light



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42. Write a note on scattering losses.
            Scattering losses in glass arise from microscopic variation in the material
density from compositional fluctuation and from structural in homogeneities or defects
occurring during fiber manufacture

43.What is Rayleigh scattering?
       The index variation causes a Rayleigh type of scattering of light. Rayleigh
scattering in glass in the same phenomenon that scatters light from sun in the
atmosphere, giving rise to blue sky.
The expression for Rayleigh scattering loss is given by
               αscat =(8π3/3λ2)(n2-1)2kBTfβT
n = refractive index
kB = boltzman constant
 βT= isothermal compressibility
Tf =fictive temperature
λ =operative wavelength


44.What is intermodal dispersion?

    Intermodal dispersion is a pulse spreading that occurs with in a single mode. the
spreading arises from finite spectral emission width of an optical source. it is called
group velocity dispersion or intermodal dispersion

45.what is intramodal delay?
        The other factor giving rise to pulse spreading is intramodal delay which is a
result of each mode having a different value of
Group velocity at a single frequency.

46.what is the measure of information capacity in optical wave guide?
     It is usually specified by bandwidth distance product in MHz.For a step index fiber
the various distortion effects tend to limit the bandwidth distance product to 20MHz.

47.Mention the losses responsible for attenuation in optical fibers.
     Absorption losses, Scattering losses and bending losses

48.What do you meant by Extrinsic absorption ?
      Absorption phenomena due to impurity atoms present in the fiber.

49. Define microscopic bending?
       Fiber losses occur due to small bending arise while the fiber is inserted into a
cable.

50. Define macroscopic bending?
        If any bending present in the fiber while cabling , the optical power get radiated

51. What are the advantages of optical communication?
1. Low transmission loss.



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2 Small size and weight.
3. No electromagnetic interference.
4. Electrical isolation.


52. Define direct band gap materials and indirect band gap materials.
In direct band gap materials direct transition is possible from valence band to
conduction band.e.g.GaAs,InP,InGaAs
In indirect band gap materials direct transition is not possible from valence band to
conduction.e.g.silicon,germanium.


53. What are the advantages of LED?
1. LEDs are less complex circuits than Laser diodes.
2. Fabrication is easier.
3. They have long life.


53. What are the two types of confinement used in LEDs?
1. optical confinement.
2. carrier confinement.


54. What are the two types of LED configurations?
1. homo junction
2. Single and double hetero junction.


55. What are the three requirements of Laser action?
1. Absorption
2. Spontaneous emission
3. stimulated emission.
56. What are the three types of Laser diode structures?
1. Gain indexed guide
2. Positive indexed guide
3. Negative indexed guide


57. What are the fundamental structures of Index guided lasers?
1. buried hetero structure.


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2. Selectively diffused construction
3. Varying thickness structure
4. Bent layer configuration.


58.What are the three basic methods of current confinement?
1. Preferential dopant diffusion.
2. Proton implantation
3. Inner strip confinement
4. Re growth of back biased PN junction.


59. Define modulation.
The process of imposing information on a light stream is called modulation. This can
be achieved by varying the laser drive current.


60. Define external quantum efficiency.
The external quantum efficiency is defined as the number of photons emitted per
radiative electron-hole pair recombination above threshold.




61. Define threshold current.
The threshold current is conventionally defined by extrapolation of the lasing region of
the power-versus-current curve. At high power outputs, the slope of the curve decreases
because of junction heating.


62. Define longitudinal modes.
Longitudinal modes are associated with the length of the cavity and determine the
typical spectrum of the emitted radiation.
63. Define lateral modes.
These modes lie in the plane of the pn junction. They depend on the sidewall
preparation and the width of the cavity.
It determines the shape of the lateral profile of the laser beam.


64. Define transverse modes.




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Transverse modes are associated with the electromagnetic field and beam profile in the
direction perpendicular to the plane of the pn junction. They determine the laser
characteristics as the radiation pattern and the threshold current density.


65. Define population inversion.
Stimulated emission will exceed absorption only if the population of the excited states
is greater than that of the ground state. This condition is called as population inversion


66. Define internal quantum efficiency.
The internal quantum efficiency is the fraction of the electron-hole pairs that recombine
radiatively.If the radiative recombination rate is R and the non radiative recombination
rateis Rnr, then the internal quantum efficiency is the ratio of the ratio of the radiative
recombination rate to the total recombination rate.


67. Differentiate LEDs and Laserdiodes.
S.No. LED                                       Laser diode
1.,     The output obtained is incoherent. The output obtained is coherent.
2.      Less expensive and less complex         More expensive and more complex.
3.      Long lifetime.                          Less lifetime.




68. What is mass action law?
Pn=ni*ni
Where p--    concentration of holes.
n concentration of electrons.
Ni    intrinsic concentration.


69. What is an intrinsic and extrinsic semiconductor material?
Intrinsic semiconductors have no impurities.
Extrinsic semiconductors contain impurities like boron and phosphorus.




70.Define responsivity




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              The performance of an avalanche photodiode is characterized by its
       responsivity
       RAPD= ηqM = Ro M
               hv
                    where Ro is the unity gain responsivity.

71.Define long wavelength cut off related to photodiode.
               The upper wavelength cutoff (λc) is determined by the band gap energy
Eg of the material. If Eg is expressed in units of electron volts(eV),then λc is given in
units of micrometers (µm) by
        λc(µm) = hc = 1.24
                 Eg Eg(eV)

72.A given APD has a quantum efficiency of 65% at a wavelength of 900 nm. If 0.5
µW of optical power produces a multiplied photocurrent of 10µA, find the
multiplication M.

       R= ηeλ
           hc
       Ip=PoR
       M= I
            Ip
73. Give some types of photodetectors.
          • Photomultipliers
          • Pyroelectric detectors
          • Semiconductor- based detectors
          • Phototransistors
          • Photodiodes

74. What are the advantages of photodiodes?
      a. Small size
      b. Suitable material
      c. High sensitivity
      d. Fast response time

75. What are the types of photodiodes?
          • PIN photodetector
          • Avalanche photodiode(APD)

76.Define photocurrent.
              The high electric field present in the depletion region causes the carriers
      to separate and be collected across the reverse-biased junction. This gives to a
      current flow in the external circuit, with one electron flowing for every carrier
      pair generated. This current flow is known as photocurrent.

77. Define quantum efficiency.
               It is defined as the number of the electron – hole pairs generated per
incident photon of energy hv and is given by
               n=No.of electron-hole pairs generated
                    No. of incident photons


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78. Define impact ionization.
                In order for carrier multiplication to take place, the photogenerated
carriers must traverse a region where a very high electric field is present. In this high
field region, a photo generated electron or hole can gain energy so that it ionizes bound
electrons in the valence band upon colliding with them. This carrier multiplication
mechanism is known as impact ionization.

79. Define avalanche effect.
               The newly created carriers are accelerated by the high electric field, thus
gaining enough energy to cause further impact ionization. This phenomenon is called
avalanche effect.

80. What is p+ ∏ p n+ reach- through structure?
                The reach –through avalanche photodiode (RAPD) is composed of a
high resistivity p-type material deposited as an epitaxial layer on a p+ substrate. A p-
type diffusion is then made in the high resistivity material, followed by the construction
of an n+ layer. The configuration is called p+ ∏ p n+ reach- through structure.

81. Define ionization rate.
                The avg. no. of electron hole pairs created by a carrier per unit distance
traveled is called ionization rate.

82. What are the conditions to be met for a high signal- to- noise ratio in a
photodetector?
                • The photodetector must have a high quantum efficiency to
                   generate a large sign al power
                • The p and amplifier noises should be kept as low as possible.

83. Define minimum detectable optical power.
              It is defined as the optical power necessare to produce a photocurrent of
the same magnitude as the root mean square of the total current.

84. Define quantum noise.
                It is not possible to predict exactly how many electron-hole pairs are
generated by a known optical power incident on the detector is the origin of the type of
short noise called quantum noise.

85. What is meant by error rate?
                 An approach is to divide the number Ne of errors occurring over a
certain time interval t by the number Nt of pulses transmitted during this interval. This
is called either the error rate or the bit error rate.
                 Bit error rate BER = Ne =Ne
                                         Nt Bt
                        Where B= 1
                                   Tb


86. Define quantum limit




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                               It is possible to find the minimum received optical
power required for a specific bit error rate performance in a digital system. This
minimum received power level is known as quantum limit.

87. Give the classifications of preamplifiers.
                    • Low impedence(LZ) preamplifier
                    • High impedence(HZ) preamplifier
                    • Transimpedence preamplifier

88. What is meant by excess noise factor?
              The ratio of the actual noise generated in an avalanche photodiode to the
noise that would exist if all carrier pairs were multiplied by exactly m is called the
excess noise factor (F).
                F = (m2) = (m2)
                     (m)2 m2

89. What is meant by inter symbol interference(ISI) ?
               ISI results from pulse spreading in the optical fibre. The presence of this
energy in adjacent time slots results in an interfering signal. Hence it is called ISI.

90.Give the advantages of Pin photodiodes.
             • Very low reverse bias is necessary
             • High quantum efficiency
             • Large bandwidth
             • Low noise level

91.What do you mean by thermal noise?
            Thermal noise is due to the random motion of electrons in a conductor.
Thermal noise arising from the detector load resistor and from the amplifier electronics
tend to dominate in applications with low signal to noise ratio.

92.Give the equation for mean square shot noise.
     The mean square shot noise is given by
           <in2>=2qIB
            IB average output current
            B bandwidth of the amplifier

93. Define multiplication M.
        The multiplication M for all carriers generated in the photodiode is defined by
                 M = IM
                       IP
              IM average value of the total multiplied output current
              IP primary unmultiplied photocurrent

94. What is current mode of operation of photodiode?
            In photoconducting mode, the photocurrent is slightly dependent on the
reverse bias. For a constant reverse bias, the current is linear. This is called current
mode of operation of the photodiode.

95. What are the system requirements?


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    The following are the key system requirements.
   • The desired or possible transmission distance
   • The data rate or channel bandwidth
   • Bit error rate(BER)

96. What are splices? What are the requirements of splices?
     The splices are generally permanent fiber joints, whereas connectors are temporary
fiber joints. Splicing is a sort of soldering. The requirements of splices are:
    • Should cause low attenuation
    • Should be strong & light in weight
    • Should have minimum power loss
    • Should be easy to install

97. What are the methods of fiber splicing?
     There are 3 methods of fiber splicing. They are:
    • Electric arc fusion splicing or fusion splicing
    • Mechanical splicing
    • V-groove splicing or loose tube splicing

98. What are connectors? What are the types of connectors?
     The connectors are used to join the optical sources as well as detectors to the optical
fiber temporarily. They are also used to join two optical fibers. The 2 major types of
connectors are:
    • Lensed type expanded beam connector
    • Ferrule type connector

99. What are the requirements of a good connector?
     The requirements of a good connector are as follows:
    • Low loss
    • Repeatability
    • Predictability
    • Ease of assembly and use
    • Low cost & reliability
    • compatibility

100. Give the 2 analysis that are used to ensure system performance?
     The 2 analysis that are used to ensure system performance are:
   • link power budget analysis
   • rise time budget analysis

101. Explain briefly about link power budget analysis?
    In the optical power loss model for a pt-to-pt link, the optical power rxed at the photo
detector depends on the amount of light coupled into the fiber & losses occurring in the
fiber at the connectors & splices. The link loss budget is derived from the sequential loss
contribution of each element in the link.
                 Loss=10 log (Pout)
                              (Pin)
The total optical power loss is,                PT = PS - PR
102. Give the range of system margin in link power budget?


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    The system margin is usually (6-8) dB. A positive system margin ensures proper
operation of the circuit. A negative value indicates that insufficient power will reach the
detector to achieve the required bit error rate, BER.

103. The specifications of the light sources are converted to equivalent rise time in rise
time budget. Why?
    A rise time budget is a convenient method to determine the dispersion limitation of an
optical link. This is particularly useful for digital systems. For this purpose, the
specifications of the light sources (both the fiber & the photo detector) are converted to
equivalent rise time. The overall system rise time is given in terms of the light source rise
time, fiber dispersion time & the photo detector rise time.

104. What are the system components of system rise time?
     The 4 basic system components that contribute to the system rise time are:
   • transmitter (source) rise time
   • receiver rise time
   • material dispersion time of the fiber
   • modal dispersion time of the fiber link
     All these 4 basic elements may significantly limit system speed.

105. Why the attenuation limit curve slopes downwards to the right?
       As the minimum optical power required at the rxer for a given BER becomes higher
for increasing data rates, the attenuation limit curve slopes downward to the right.

106. What are the noise effects on system performance?
      The main penalties are modal noise, wavelength chirp, spectral broadening,
mode- partition noise.

107. Define modal noise?
      It arises when the light from a coherent laser is coupled in to a multimode fiber
operating at 400Mbps and higher. It mainly occurs due to mechanical vibrations and
fluctuations in the frequency of the optical source.

108. What are the measures to avoid modal noise?
      The measures are
          • use LEDs
          • use LASER having more longitudinal modes
          • use a fiber with large numerical aperture
          • use a single mode fiber

109. Define mode partition noise?
       The mode partition noise is associated with intensity fluctuations in the
longitudinal modes of a laser diode. It becomes more pronounced for the higher bit
rates.

110. What is meant by chirping?
       It means that the dynamic line broadening (line broadening is a frequency chirp)
in the laser which oscillates in the single longitudinal mode under CW operation when
the injection current is intensity modulated.
111. What is the best way to minimize the chirping?


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     It is to choose the laser emission wavelength close to the zero-dispersion of the
wavelength of the fiber.

112. What is reflection noise?
      It is the optical power that gets reflected at the refractive index discontinuities
such as in splices, couplers and filters, or connectors. The reflected signals can degrade
both the transmitter and receiver performance.

113. What are the effects of reflection noise in high speed systems?
       They cause optical feedback which leads to optical instabilities that may lead to
intersymbol interference and intensity noise.

114. What are the techniques to reduce optical feedback?
                    Fiber end faces with a curved surface to the laser emitting facet.
              Index matching oil or gel at air glass interfaces.
              PC connectors
              Optical isolators within the transmitter module.

115. What are the basic performances of the WDM?
            • Insertion loss
            • Channel width
            • Cross talk

116. What is WDM? Define.
       WDM is wavelength division multiplexing. The optical beam consists of
different wavelengths and several channel information is transmitted over a single
channel.

117. What is meant as bidirectional WDM?
      A single WDM which operates as both multiplexing and demultiplexing
Devices is said as the bidirectional WDM.


118. Define Radiance.
     Radiance (or brightness) is a measure, in Watts, of the optical power radiated into a
unit solid angle per unit area of the emitting surface.

119. What is meant by ‘population inversion’?
     In thermal equilibrium, the density of excited electrons is very small. Most
photons incident on the system will therefore be absorbed, so that stimulated emission
is essentially negligible. Stimulated emission will exceed absorption only if the
population of the excited states is greater than that of the ground state. This condition is
known as population inversion.

120. What are the factors to be considered in link power budget?
     The factors to be considered in link power budget are:
         • transmission speed
         • optical sources & detectors
         • optical fiber
121. What are the causes of absorption?


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     Normally, the system is in the ground state. When a photon of energy hγ12
impinges on the system, an electron in state E1 can absorb the photon energy & be
excited to state E2.

122. What is meant by hetero junction?
     In hetero junction, two different alloy layers are on each side of the active region.
Because of the sandwich structure of differently composed alloy layers, both the
carriers & optical field are confined in the central active layer.

123. What is meant by indirect band gap semiconductor material?
     For indirect band gap materials, the conduction-band minimum & the valence-
band maximum energy levels occur at different values of momentum. Here, band-to-
band recombination must involve a third particle to conserve momentum, since the
photon momentum is very small. Phonons serve this purpose.

124. What is meant by ‘modal noise’?
     It arises when light from a laser is coupled into the multimode fiber.

 125.What is the necessity of cladding for an optical fiber?
      a) To provide proper light guidance inside the core
      b) To avoid leakage of light from the fiber
      c) To avoid mechanical strength for the fiber
      d) To protect the core from scratches and other mechanical damages


                                    16 MARKS :

   1. Discuss the mode theory of circular waveguides.
                  • Overview of modes
                        Electric field distributions for lower-order guided modes
                  • Key modal concepts
                  • Maxwell’s Equations
                  • Waveguide equations
                  • Waveguide equations for Step-Index Fibers
                  • Modal equation
                  • Modes in Step-Index Fibers
                  • Linearly polarised modes
                  • Power flow in Step-Index Fibers


   2. Explain in detail about fiber materials.
         • Requirements of optical fibers
         • Glass fibers
         • Halide Glass fibers
         • Active Glass fibers
         • Chalgenide Glass fibers
         • Plastic optical fibers




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   3. Explain in detail about single-mode fiber.
         • Dimensions of core diameter
         • Mode-field diameter
              Distribution of light in a single-mode fiber above its cutoff wavelength
         • Propagation modes
                  i.    Fiber birefringence
                 ii.    Fiber beat length


   4. Discuss the structure and numerical aperture of graded index fiber.
         • Power law relationship
         • Index difference
         • Numerical aperture
         • Number of bound modes


   5. Explain in detail about fiber fabrication.
         • Outside vapour- phase oxidation
         • vapour- phase axial deposition
         • modified chemical vapor deposition
         • plasma activated chemical vapor deposition
         • Double crucible method



  6. What is waveguide dispersion? Derive expression
           Wave-guide dispersion, which occurs because a single mode fiber confines
   only 80% of the optical power to the core. Dispersion thus arises since the 20% of
   the light propagating in the cladding travels faster than the light confined to the
   core. The amount of wave-guide dispersion depends on the fiber design, since the
   modal dispersion constant β is a fn of (a / λ)

7. What is material dispersion ? Derive Expression
           Material dispersion occurs because the index of refraction varies as a
    function of the optical wavelength.

8.Explain –design optimization of single mode fibers
      refractive index profile:
1.For achieving a maximum transmission distance of a high-capacity link, the
dispersion null should be at the wavelength of minimum attenuation.
2.Four main categories
        a.1300 nm optimised fibers
        b.dispersion-shifted fibers
        c.dispersion-flattened fibers
        d.large-effective core area fibers.
3.matched cladding fibers have a uniform refractive index throughout the cladding.
4.typical mode field diameters are 9.5 micro meter and core-to-cladding index
differences are around o.37%.



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5.material dispersion depends only on the composition of the material.
6.an alternative is to reduce fiber dispersion by spreading the dispersion minimum out
over a wide range. This approach is known as dispersion flattening.

9.What is Pulse Broadening?Derive the expression for the same in Graded index
Waveguides.

        Dispertion induced signal distortion is that a light pulse will broaden as it
travels along the fibre.This pulse broadening causes a pulse to overlap with
neighbouring pulses.After a time ‘t’,the adjacent pulses can no longer be individually
distinguished at the receiver and error will occur.

10.Signal distortion in optical waveguide-Explain
        Distortion due to
                1.Intramodal dispersion
                2.Intermodal delay effects.
        The distortion effects are explained by examining the behaviour of the group
velocities of the guided mode..


11.Signal distortion in optical waveguide- explain

   1.optical signal gets distorted as it travels along a fiber
    2.distortion is due to intramodal dispertion and intermodal delay
    3.it is explained by examining the behaviour of the group velocities of the guided
mode.
    4.intramodal dispersion depends on wavelenth and its effect on signal distortion
increases with a spectrum width of the optical source
    5.waveguide dispersion occurs because a single mode fiber cofines only 80% of the
optical power to the core.
    6.the other factor giving rise to pulse spreading having a different value of group
velocity at a single frequency.
    7.among the 3 waveguide dispersion can be ignored in multimode fibers but it is
significant in single mode fiber.
    8.there are 3 distortion can be mitigated by
           a)optical power launching conditions
           b)non uniform mode attenuation
           c)mode mixing in the fiber and splices
           d)by statistical variation
           e)non ideal index profile

12.Give an account on the direct and indirect band gap materials.


Direct band gap materials:
In direct band gap materials direct transition is possible from valence band to
conduction
band.e.g.GaAs,InP,InGaAs



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The electron and the hole have the same momentum value.


Indirect band gap materials:
In indirect band gap materials direct transition is not possible from valence band to
conduction.e.g.silicon,germanium.
The electron and the hole have the different momentum value.


13.Give an account on LED structures.


Surface emitters:
Also called as burrus or front emitters.
The plane of the active light-emitting region is oriented perpendicularly to the axis of
the fiber.
The emission pattern is isotropic with a 120 half-power beam width.


Edge emitter:
Consists of an active junction region, which is the source of the incoherent light, and
the two guiding layers.
The refractive index of the guiding layers is less than the active region.
The emission pattern of the edge emitter is more directional than that of the surface
emitter.




14. Give an account on the Laser diode modes.
Fabry-Perot resonator:
It consists of partially reflecting mirrors that are directed toward each other to enclose
the cavity.
The purpose of these mirrors is to provide strong optical feedback in the longitudinal
section.
The device will oscillate at the resonant frequencies.
Distributed feedback configurations:
In this case lasing action is achieved by Bragg reflectors.
A pattern of electric and magnetic field lines are set up which are called the modes of
the cavity.


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The different modes are longitudinal, transverse, and lateral.
Longitudinal modes are associated with the length of the cavity and determine the
typical spectrum of the emitted radiation.
These modes lie in the plane of the pn junction. They depend on the sidewall
preparation and the width of the cavity.
Transverse modes are associated with the electromagnetic field and beam profile in the
direction perpendicular to the plane of the pn junction. They determine the laser
characteristics as the radiation pattern and the threshold current density determines the
shape of the lateral profile of the laser beam


15. Give an account on the optical confinement of lasers.


1. Gain indexed guide
2. Positive indexed guide
3. Negative indexed guide


Indexed lasers have the following structures.


1. buried hetero structure.
2. Selectively diffused construction
3. Varying thickness structure
4. Bent layer configuration.


16. Give an account on single mode lasers and modulation of laser diodes.


Single mode lasers:
It is used for long-distance communication.
It consists of a single longitudinal mode and single transverse mode.
The spectral width is low.
Alternative devices developed are
1. Vertical cavity surface emitting lasers
2. Structures that have a built-in frequency-selective grating.
3. Tunable lasers.


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Modulation:
The process of imposing information on a light stream is called modulation. This can
be achieved by varying the laser drive current
Pulse modulation is used.

   17. Discuss the receiver operation with neat block diagram.
              Digital signal transmission
                 Fig) Signal path through an optical data link
              Error sources
                      Fig)Noise sources and disturbances in the optical pulse detection
              mechanism
              Receiver configuration
                      Fig) Schematic diagram of a typical optical receiver
              Fourier transform representation


   18. Write in detail about avalanche photodiodes and explain briefly about
       photodetector noise and SNR.

         Avalanche photodiodes
          a. Impact ionization
          b. Avalanche effect
          c. Reach-through construction
          d. p+ ∏ p n+ reach- through structure
          e. Principle of reach through
          f. Ionization rate

        Photodetector noise
                SNR at output of an optical receiver
                Condition to achieve a high SNR

         SNR

           S=         (ip2)M2
           N  2q(Ip+ID)M2F(M)+2qILB+4KBTB/RL

   19. An InGaas pin photodiode has the following parameters to wavelength of
       1300nm: ID=4 nA, η=0.9,RL=1000           and the surface leakage current is
       negligible. The incident optical power is 300nW (-35 dBm), and the receiver
       bandwidth is 20 MHz. Find the various noise terms of the receiver.

                        Shot noise = ηPoe
                                      hf
                  Total shot noise =2eB(ID+ Ip)
                   Thermal noise = 4KTB
                                      RL



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   20. Discuss the performance of digital receiver by defining the probability of error.

                        Bit error rate
                        Probability distributions
                          Fig)Probability distributions for received 0 and 1 signal
                    pulses
                        Mean - square noise voltage
                           Fig)Gaussian noise characteristics of a binary signal
                        Error function
                             Fig) Plot of the BER(Pe) versus the factor Q.


   21. Explain the error sources of fundamental receiver operations.

                  Errors due to noises and disturbances in the signal detection system
                  Definition of noise
                  Types of noises
                      i.  Internal noise
                     ii.  External noise
                  Other types
                    i.   shot noise
                   ii.   thermal noise
                 Fig) Noise sources and disturbances in the optical pulse detection
                 mechanism
                 Photocurrent
                 Inter symbol interference(ISI)
                 Fig)Pulse spreading in an optical signal that leads to ISI.
22. Explain in detail about the system considerations?
    •      The 3 system considerations
    • Transmitting distance: decide wavelength-choose components-txion distance is
       not long, operate in (800-900) nm region-txion distance is long; operate in
       (1300-1550) nm region.
    • Optical source & detectors:
           o Choose photo detector & optical source, compute characteristics of fiber
           o Detect the amount of light falling on detector to satisfy BER.
           o Pin photodiode rxer is simpler, stable, less expensive, need low bias vge
               (<50V) than avalanche photodiode.
           o Signal dispersion, data rate, txion distance & cost decides source (LED
               & LASER).
           o In laser, spectral width is narrow, couple (10-15) db more optical power,
               greater repeated, less txion, but complex circuitry.
    • Optical fiber:
           o Select single-mode or multimode either a step-index or graded-index
                               core.
           o Multi-mode fibers used with LEDs, LASERs use single-mode or multi-
               mode fibers.
           o Optical power coupled depends on core-cladding index difference &
               thus numerical aperture.
           o Single-mode fiber provides ultimate bit-rate distance products of about



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              30 Gbps/km.
   •   Disadvantages of single-mode fiber
   •   When choosing the attenuation characteristics of a cabled fiber, the extra losses
       from cabling process must be added to the fiber attenuation.

23. Explain in detail about the methods of fiber splicing?
    •    The 3 methods of fiber splicing
    •    Electric arc fusion splicing or fusion splicing
           •      Figure
           •      Broken fiber edges aligned, pressure is applied; heat is applied
           •      Unite as a single fiber
           •      Plastic jacket made of epoxy resin to cover the splice
           •      Loss of (0.25-0.1)db is achieved
    • Mechanical splicing or elastic tube splicing
           •       Figure
           •       Broken fiber edges aligned, locked in position with positioning
                   devices & optical cement
           •       Edges polished, splicing compound added
           •       Central hole diameter of precision tube is similar than fiber
           •       Insert fiber, expands hole diameter
           •       A symmetrical force allows accurate or automatic alignment of the
                   axis of two joined fibers
    • V-groove splicing or loose tube splicing
           o Figure
           o Fiber ends are fixed in v-shaped groove
           o Grooved silicon, plastic ceramic or metal substrate
           o Splice loss dependent on metal size

24. Explain about the two types of connectors?
    •    The 2 types of connectors.
    •    Lensed type/ Expanded beam connectors
           •      Figure
           •      Two lenses: Collimator lens & pre focusing lens
           •      Adjust the two lenses, optical signal from one fiber is connected to
                  other.
    • Ferrule type connector
           o Figure
           o Fibers placed in ferrule, fixed by an adhesive material
           o Brought together under cylindrical sleeves.

25. Explain in detail about link power budget & rise time budget?
    • Link power budget: In the optical power loss model for a pt-to-pt link, the
       optical power rxed at the photo detector depends on the amount of light coupled
       into the fiber & losses occurring in the fiber at the connectors & splices. The
       link loss budget is derived from the sequential loss contribution of each element
       in the link.
    • Figure
    • Formula


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   •   System margin is usually (6-8) db.
   •   Rise time budget: It is a convenient method to determine the dispersion
       limitation of an optical link. This is particularly useful for digital systems. For
       this purpose, the specifications of the light sources are converted to equivalent
       rise time. The overall system rise time is given in terms of the light source rise
       time, fiber dispersion time & the photo detector rise time.
   •   Formula
   •   Basic system components

26. Discuss the operational principles of WDM and its key features?
     An optical beam consists of different wavelengths. Several channel information are
transmitted over a single channel and increases the information carrying capacity.
     The three basic performance of WDM are:
            o Insertion loss: amount of power loss arises from the fiber optic link by
            the addition of WDM coupling devices. Also the loss occurs at the junction
            of the fiber optic link to the WDM device.
            o Channel width: wavelength range allocated to a particular source. For
            lasers, channel width is several 10s of nm required for no interference.
            o Cross talk: problem at the receiver caused by the mixing of two or more
            channels. It depends on the application. Tolerable level is above -30 dB.

27. Describe the noise effects on the system performance?
          It is assumed that the optical power falling on the photo detector is a clearly
defined function of time within the statistical nature of the quantum detection process
but in reality various interactions between spectral imperfections in the propagating
optical power and the dispersive waveguide give rise to the variations in the optical
power level falling on the photo detector. The main penalties are modal noise,
wavelength chirp, spectral broadening, mode- partition noise.
    Modal noise: It arises when the light from a coherent laser is coupled in to a
    multimode fiber operating at 400Mbps and higher. It mainly occurs due to
    mechanical vibrations and fluctuations in the frequency of the optical source.
    The measures to avoid are:
                        use LEDs
                        use LASER having more longitudinal modes
                        use a fiber with large numerical aperture
                        use a single mode fiber
    Mode partition noise: The mode partition noise is associated with intensity
    fluctuations in the longitudinal modes of a laser diode. It becomes more pronounced
    for the higher bit rates.
    Chirping: It means that the dynamic line broadening (line broadening is a frequency
    chirp) in the laser which oscillates in the single longitudinal mode under CW
    operation when the injection current is intensity modulated. They cause optical
    feedback which leads to optical instabilities that may lead to inter symbol
    interference and intensity noise.
    Reflection noise: It is the optical power that gets reflected at the refractive index
    discontinuities such as in splices, couplers and filters, or connectors. The reflected
    signals can degrade both the transmitter and receiver performance. They cause
    optical feedback which leads to optical instabilities that may lead to inter symbol
    interference and intensity noise.



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28. (a)(i) Discuss the operational principles of WDM.
     (ii) Describe the key features of WDM.
           An optical beam consists of different wavelengths. Several channel
information are transmitted over a single channel and increases the information
carrying capacity.
           The three basic performance of WDM are:
            o Insertion loss: amount of power loss arises from the fiber optic link by
            the addition of WDM coupling devices. Also the loss occurs at the junction
            of the fiber optic link to the WDM device.
            o Channel width: wavelength range allocated to a particular source. For
            lasers, channel width is several 10s of nm required for no interference.
            o Cross talk: problem at the receiver caused by the mixing of two or more
            channels. It depends on the application. Tolerable level is above -30 dB.

  (b) Explain the rise-time budget of a fiber-optic point-to-point link.
       •      Rise time budget: It is a convenient method to determine the dispersion
       limitation of an optical link. This is particularly useful for digital systems. For
       this purpose, the specifications of the light sources are converted to equivalent
       rise time. The overall system rise time is given in terms of the light source rise
       time, fiber dispersion time & the photo detector rise time.
       •      Formula
       •      Basic system components




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TELEVISION
 AND VIDEO
  ENGINEERING




                90
                Electronics &Communication Engineering
                              Subject code: EC 1011
                    Subject: Television and Video Engineering
                           (For seventh semester ECE )


                         2 Mark Questions and Answers




1. Mention the major function of the camera tube?
        The major function of the camera tube is to convert an optical image into
electrical signals.

2. Define visual acuity?
        Visual acuity can be defined as the ability of human eye to resolve finer
details in a picture

3. What do you refer by persistence of eye?
      The persistence of eye refers to the storage capability of the human eye

4.Define luminous intensity?
        It is the measure of light intensity responsible for stimulating visual
sensation.

5.Define aspect ratio?
       Aspect ratio can be defined as the ratio of width to height of the picture
frame. For television, it is standardized as 4:3.

6.Define luminous flux?
        Luminous flux can be defined as the radiated luminous power or power of
visible light expressed interms of its effect on the average or normal human eye.

7.Define luminance?
       Luminance can be defined as the quantity of light intensity emitted per
square centimeter of an illuminated area.

8.What do you understand by illuminance?
      Illuminance is the average luminous flux incident on to a surface.

9.what do you mean by resolving power or resolution?
        It is the ability of the image reproducing system to represent the fine
structure of an object.




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10.Mention some important characteristics of human eye?
      Visual acuity, persistence of vision, brightness and colour sensation are
some of the important characteristics of human eye.

11.What are rods and cones?
       The retina of the human eye consists of light sensitive cellular structures
of two kinds namely rods and cones. The rods sense primarily the brightness
levels including very faint impressions. The cones are mainly responsible for
colour perception. There are 65 lakhs cones and about 10 crores rods connected
to the brain through 8 lakhs optic nerve fibres.


12.Give the relationship between eye parameters?
       The eye parameters are related by the following equation:

                      B=constant / c2α02
       Where,
                c- the constant ratio
                b-the scene brightness
                α0 - the minimum resolvable angle

13.Why is scanning necessary in television system?
        Scanning is the important process carried out in a television system inorder
to obtain continuous frames and provides motion of picture. The scene is scanned
both in the horizontal and vertical directions simultaneously in a rabid rate. As a
result sufficient number of complete picture of frames per second is obtained to
give the illusion of continuous motion.

14.What do you understand by flicker?
       The result of 24 pictures per second in motion pictures and that of scanning
25 frames per second in television pictures is enough to make an illusion of
continuity. But, they are not rapid enough to permit the brightness of one picture
or frame to blend smoothly in the next through the time when the screen is
blanked between successive frames. This develops in a definite flicker of light that
is very irritating to the observer when the screen is made alternately bright and
dark.

15.How will you solve the flickering problem?
       The flickering problem is solved in motion pictures by showing each
picture twice. Hence 48 views of the scene are shown per second although they
are still the same 24 pictures frames per second. As a result of the increased
blanking rate, flicker is removed. In TV, Interlaced scaning is used to avoid flicker

16.What do you mean by interlaced scanning?
       When the scanning beam reaches the bottom of the picture frame, it
quickly returns to the top to scan those lines that were missed in the previous



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scanning. Hence the total number of lines are divided into two groups called
fields. Each field is scanned alternately. This way of scanning is called interlaced
scanning.

17.Define vertical resolution?
        The capability of resolving picture details in the vertical direction is called
vertical resolution.

18.What is horizontal resolution?
       The ability of the system to resolve maximum number of picture elements
along the scanning lines determines horizontal resolution.

19.List the contents of a composite video signal?
       Composite video signal consists of a camera signal, blanking pulses and
synchronizing pulses.

20.What do you mean by pedestal?
       The difference between the black level and blanking level is known as the
pedestal.

21.Define peak-white level?
       The peak-white level is defined as the level of the video signal when the
picture detail being transmitted corresponds to the maximum whiteness to be
handled

22.Define pedestal height?
       Pedestal height is the distance between the pedestal level and the average
value axis of the video signal.

23.What is the main function of the blanking pulses?
       The composite video signal consist of blanking pulses to make the retrace
lines invisible by increasing the signal amplitude little above the black level of
75percent during the time scanning the circuits develop retrace.

24.What are per the post equalizing pulses?
       To rectify the drawback which occurs on account of half-line discrepancy
five narrow pulses are added on either side of the vertical sync pulse. These are
called pre-equalising and post-equalising pulses .

25. Differentiate monochrome and colour camera tube.
        In black and white camera only one pickup tube is needed but three such tubes or
its equivalent is necessary in color cameras to develop separate signals for red ,green and
blue information present in the scene.


26.   Why do we prefer horizontal polarization for television receiving antenna?



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           We prefer horizontal polarization for television receiver antenna because it
   results in more signal strength, less reflection and reduced ghost images.

27.Where can you employ indoor receiver antennas?
          In strong signal areas it is sometimes feasible to use indoor antennas
   provided the receiver is sufficiently sensitive.

28.A yagi antenna with a large number of directors is commonly used with
success in fringe areas for stations in the vhf band.

29.What do you understand by diplexer?
          The outputs of both the video and the audio transmitter are
   combined by the diplexer circuit and given to a common broadcast
   transmitting antenna.

30. If two stations are operating at the same carrier frequency and located
nearby then they will interface with each other. This is called co-cannel
interference and it is common in fringe areas.

31 It is the interference due to stations located nearby and allocated as
adjacent channels.

32.Define guard band?
          Guard band can be defined as a small frequency band introduced
   between two consecutive channels inorder to reduce interference .

33. Ghost interference arises as a result of discrete reflections of the signal
from the surface of hills, bridges, buildings, towers etc.

34.Mention the requirements of high level modulation?
          In high level modulation, the video signal has to be modulated by
   the picture carrier in the final power amplifier which has a high power
   level. Grid bias modulation is employed.

35.What do you understand by ground waves?
          Vertically polarized electromagnetic waves are radiated at zero or
   small angles with ground. They are guided by the conducting surface of
   the ground along which they are propagated. Such waves are known as
   ground or surface waves. As the ground waves travel along the surface of
   the earth, their attenuation is proportional to frequency. The attenuation is
   reasonably low below 1500KHz.Therefore, all medium wave broadcast and long
   wave telegraph and telephone communication is carried out by ground wave
   propagation.




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36.What are sky waves?
           In ground wave propagation ,frequencies above 1600 KHz does not serve
   any useful purpose as the signal gets very much attenuated within a short distance
   of its transmission .Therefore ,most radio communication in short wave bands
   upto 30MHz is carried out by sky waves.When these waves are transmitted high
   up in the sky , they travel in the straight line until the ionosphere is reached. This
   region begins about 120Km above the surface of the earth. The region consists of
   large concentrations of charge gaseous ions, free electrons and neutral molecules.
   The ions and free electrons cause to band all passing electromagnetic waves.

37.Describe briefly about space wave propagation.
           Propagation of radio waves above about 40MHz is not possible through
   either sky wave or surface wave propagation .Therefore ,the only alternative for
   transmission in the VHF and UHF bands, despite large attenuation is by radio
   waves which travel in a straight line from transmitter to receiver. This called
   space wave propagation.

38.Why is AM preferred over FM broadcasting the picture signal?
           If FM is adopted for picture transmission ,the changing beat frequency
   between the multiple paths delayed with respect to each other would develop a
   bar interference in the image with a shimmering effect as the bars continuously
   changes as the beat frequency changes therefore ,no study picture is
   produced.Apart from that ,circuit complexity and BW requirements are much less
   in AM than FM.Hence AM is preferred to FM for broadcasting the picture signal.

39.What is Dipole array?
           Dipole antenna is used for band I&III transmitters. It consists of diploe
   pnels mounted on the four sides at the top of the antenna tower.Each panel has an
   array of full wave dipoles mounted in front of reflectors. To get an unidirectional
   pattern ,the four panels mounted on the four sides of the tower are so fed that the
   current in each lags behind the previous by 90 degree . This is done by changing
   the field cable length by λ/4 to the two alternate panels and by reversal of polarity
   of the current.

40. Define Image rejection ratio.
           Image rejection ratio is defined as the output due to desired station divided
    by output due to image signal.

41. What do you refer by Yagi uda Antenna?
            This is a widely used antenna for television receivers .Generally ,for
    locations within 40 to 60Km from the transmitter is the folded dipole with one
    reflector and one director. This is commonly called Yagi antenna or Yagi-Uda
    antenna.

42. Name the essential parts of TV transmitter.




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          The essential parts of TV tranmitter includes a video processing unit . A
   visual modulator which is a diode bridge modulator, phase compensator or delay
   equalizer and frequency converter.

43. What is the main purpose of using VHF tuner?
           The purpose tuner unit is to amplify both picture and sound signals picked
    up the antenna and to convert the carrier frequencies and their associated side
    bands into intermediate frequencies.

44. Name the essential components of RF section.
           RF tuner section consists of RF amplifier ,mixer and local oscillator and is
    normally mounted on a separate subchasis,called the front end.

45. What are the major tasks to be done by detector?
            The video detector is designed to recover composite video signal and to
    transform the sound signal to another lower carrier frequency.

46. Why is video amplifier required?
           The amplitude of the composite video signal at the output of video
    detector is not enough to drive the picture tube directly . Therefore further
    amplification is required. This is done by video amplifier.

47. What are Sync pulses?
            The Synchronizing pulses called ‘Sync’ are part of the composite video
    signal as the top 25% of the signal amplitude. The sync pulses include horizontal
    ,vertical and equalizing pulses. Sync separator separates these signals from the
    video signal.

48. Define frequency Distortion.
            The inequality in gain at different frequency components of the received
    signal is called frequency distortion.

49. List out the advantages of IF sections.
             The main function of this section is to amplify modulated IF signal over
    its entire bandwidth with an input of about 0.5mV signal from the mixer to deliver
    about 4V into the video detector.
    IF section is used to equalize amplitudes of sideband components ,because of
    vestigial side band transmission.
    IF section is used to reject the signals from adjacent channels.

50. What is meant by high level modulation.
            In high level modulation modulation occurs in the output circuit of the
    final amplifier.


11. What do you understand by Hue?



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   Hue or tint can be defined as the predominant spectral colour of the received light.
   The colour of any object is distinguished by its hue or tint.

12. Define Brightness.
            Brightness can be defined as theamount of light intensity as perceived by
    the eye regardless of the colour.

13. What do you mean by saturation?
    Saturation refers to the spectral purity of the colour light.It indicates the degree by
    which the colour is diluted by white.

14. List any three requirements to be satisfied for compatibility in television systems.
        a. It should has the same bandwidth as the corresponding monochrome
           signal.
        b. The colour signal should have the same brightness information as that of
           monochrome signal.
        c. The location and spacing of the picture and sound carrier frequencies
           should remain the same.

15. What is additive mixing?
            All light sensations to the eye are splitted in to three main colour groups
    namely red,blue and green. The optic nerve system integratesthe different colour
    impressions in accordance with the curve to perceive the actual colour of the
    object.

16. State grassman’s law.
            The brightness impression produced by the three primaries that constitute
    the single light. This property of the eye of generating a response which depends
    on the algebraic sum of the blue ,red and green inputs is called grassman’s law.

17. Explain the significance of generating colour difference signals.
           Colour difference signals are generated to avoid the separate transmission
    of R,G,B signals.

18. Why is (G-y) not suitable for transmission?
           The proportion of G is large in luminance signal,hence magnitude of (G-
           Y) is relatively small so it requires amplifiers at the receiving end.
           It affect the signal to noise ratio at the transmitting end.

19. What is gamma correction.
    A colour camera is used develop three voltages proportional to red,green and blue
    colour contents of the picture.These voltages are represented as R,G,B.a
    correction is applied to these voltages to compensate for any nonlinearity of the
    system and that of the picture tube.This is called gamma correction.i.e. the camera
    tube output voltage amplitudes are normalized to I V p-p level.




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20. what do you mean by compatibility?
    Compatibility means that a colour TV signal can produce a black and white
    picture on a monochrome receiver and signals from a black and white system can
    provide a monochrome picture on a colour receiver.

21. What do you mean by colour burst?
    In PAL system the two carrier components are suppressed in the balanced
    quadrature modulator it is necessary to regenerate at the receiver for
    demodulation .For this ,8 to 10 cycles of the colour subcarrier oscillator output at
    the encoder are transmitted along with other sync pulses. This sample of the
    colour subcarrier called colour burst,is placed at the back porch of each horizontal
    blanking pulse pedestal.

22. What is swinging burst?
    The PAL burst phase actually swings 45 about the –U axis from line to line and
    indicates the same sign as that of the V signal;thus the switching mode
    information is the swinging burst.this is known as swinging burst.

23. Merits of SECAM system.
           SECAM system has several advantages because of frequency modulation
           of the subcarrier and transmission of one line at a time.
           SECAM receivers are immune to phase distortion.
           Both the luminance and chrominance signals are not present at the same
           time ,there is no possibility of cross talk between the colour difference
           signals.
           Ther is no need for the use of QAM at the transmitter and synchronous
           detectors at the receiver.
           The receiver does not need Automatic tuning control and Automatic color
           control

24. Demerits of SECAM system.
           In SECAM system luminance is represented by the amplitude of voltage
    but hue and saturation are represented by deviation of the subcarrier.when a
    composite signal involving luminance and chrominance is faded out in studio
    operation,it is the luminance signal that is readily attenuated and not6 the
    chrominance.This makes the color more saturated during fade to black.

25. Limitations of the NTSC system.
            The NTSC system is sensitive to transmission path differences which
    introduces phase errors that result in colour changes in the picture. At the
    transmitter,phase changes in the chroma signal take place when change over
    between programmes of local and television network systems takes place and
    when video tape recorders are switched on .The phase angle is also affected by
    the level of the signal while passing through various circuits .In addition cross talk
    between demodulator outputs at the receiver causes colour distortion.




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26. Mention some features of PAL system.
      a. The weighted (B-Y) and (R-Y) signals are modulated without being given
          a phase shift of 33 as is done in the NTSC system.
      b. On modulation both the color difference signals are allowed the same
          bandwidth of about 1.3MHz.
      c. The color subcarrier frequency is chosen to be 4.43MHz.
      d. The weighted color difference signals are quadrature modulated with the
          subcarrier.

27. Write notes on NTSC system.
           NTSC system is compatible with 525 line American system.In order to
    maintain compatibility two new colour difference signals are generated and they
    are represented as I and Q. Since eye is capable of resolving finer details in the
    regions around I,it is allowed to have a maximum bandwidth of 1.5MHz.The
    bandwidth of Q signal is restricted to 0.5MHz.

28. What is the difference between NTSC,PAL and SECAM?
            The difference between the SECAM system on one hand and NTSC and
    PAL on the other is that the later transmit and receive two chrominance signals
    simultaneously while in the SECAM system only one of the two color difference
    signal is transmitted at a time.

29. What do you mean by high frequency preemphasis?
            In SECAM system, the chrominance signals are pre-emphasized before
    modulation. After modulating the carrier with the pre-emphasized and weighted
    color difference signals, another form of preemphasis is carried out on the signals.
    This takes the form of increasing amplitude of the sub carrier as its deviation
    increases. Such a preemphasis is called high frequency preemphasis.

30. What is the use of line identification pulses?
            In SECAM system ,the switching of Dr and Db signals line by line takes
    place during the line sync pulse period.The sequence of switching continues
    without interruption from one field to the next and is maintained through the field
    blanking interval.However it is necessary for the receiver to be able to deduce as
    to which line is being transmitted.Such an identification of the proper sequence of
    color lines in each field is accomplished by identification pulses.


71. Write notes on luminance channel.
    The video amplifier in the luminance channel is Dc coupled and has the same
    bandwidth as in the monochrome receiver. It is followed by a delay line to
    compensate for the additional delay the color signal suffers because of limited
    bandpass of the chrominance amplifier .This ensures time coincidence of the
    luminance and chrominance signals. The channel also includes a notch filter
    which attenuates the subcarrier by about 10db.This helps to suppress the
    appearance of any dot structure on the screen along with the color picture.



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72. What is the use of chrominance bandpass amplifier?
           The chroma bandpass amplifier selects the chrominance signal and rejects
    other unwanted components of the composite signal.

73. What do you mean by automatic color control?
            The ACC circuit is similar to the AGC circuit used for automatic gain
    control of RF and IF stages of the receiver.It develops a dc control voltage that is
    proportional to the amplitude of the color burst.


74. Write short notes on color killer circuit.
            When a monochrome transmission is received there is no input to the color
    killer and no positive voltage is developed . Therefore no input is given to the
    second chroma amplifier from the color killer circuit ,it blocks the second chroma
    amplifier.Thus it prevents the color noise on black and white picture.

75. Merits of PAL system.
            The problem of differential phase errors has been successfully overcome
    in the PAL system.

76. Demerits of PAL system.
    The use of phase alteration by line technique and associated control circuitry
    together with the need of a delay line in the receiver makes the PAL system more
    complicated and expensive.The receiver cost is higher for the PAL colour system.

77. What do you mean by automatic frequency tuning?
    AFT is used to improve the stability of the oscillator circuit ,some drift does occur
    on account of ambient temperature changes ,component aging ,power supply
    voltage fluctuation and so on. The fine tuning control is adjusted to get a sharp
    picture.

78. Write short notes on burst seperator.
            The burst seperator circuit has the function of extracting 8 to 10 cycles of
    reference color burst which are transmitted on the back porch of every horizontal
    pulse .the circuit is tuned to the subcarrier frequency and is keyed on during the
    flyback time by pulses derived from the horizontal output stage.

79. What is the use of color subcarrier oscillator?
    The function of subcarrier oscillator is to generate a carrier wave output at
    3.57MHz and feed it to the demodulators.The subcarrier frequency is maintained
    at its correct value and phase by the APC circuit.


80. How the phase error is cancelled in the PAL system.




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           In PAL system phase shift error is cancelled by reversing the phase angle
   of v signal on alternate lines.

81. Give the abbreviation for NTSC, SECAM ,and PAL.
           NTSC -National Television systems committee
           SECAM –Sequential –a-Memoire
           PAL - Phase Alteration by Line

82. What do you understand by PAL –D Colour system.
    The use of eye as the averaging mechanism for the correct hue is the basic
    concept of simple ‘PAL’ system. Beyond a certain limit , the human eye see the
    effect of colour changes on alternate lines hence the system needs modification.
    Considerable improvement found in the system of a delay line is used to do the
    averaging first and then present the color to the eye.This is called PAL-D or delay
    line PAL method and is most commonly employe in PAL receivers.

83. Write short notes on colour subcarrier frequency of PAL D system.
    The color sub carrier frequency of 4.43MHz is produced with a crystal controlled
    oscillator .To accomplish minimum raster disturbance through the color
    subcarrier it is important to maintain correct frequency relationship between the
    scanning frequencies and subcarrier frequency .Therefore ,it is usual to count
    down from the subcarrier frequency to twice the line frequency pulses .

84. write short notes on AGC circuit.
    AGC circuit is used to control the gain of RF and IF amplifiers .The change in
    gain is achieved by shifting the operating point of transistors used in the
    amplifiers.The operating point is changed by a bias voltage that is developed in
    the AGC circuit.

85. What do you mean by Peak AGC system?
          The system based on sampling the sync tip levels is known as “peak”
    AGC system.The Peak AGC system is also called as non-keyed AGC sytem.

86. What are the two types of AGC control?
          Forward AGC control
          Reverse AGC control

87. What is Forward AGC control?
In any transistor amplifier ,gain is varied by shifting the operating point either
towards collector current cutoff or saturation. This actually varies beta of the
transistor and hence the stage gain changes.When gain is changed by shifting the
operating point towards current cutoff ,then it is called “Reverse AGC”.

88. What is forward AGC?
In any transistor amplifier ,gain is varied by shifting the operating point either
towards collector current cutoff or saturation. This actually varies beta of the



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transistor and hence the stage gain changes.When gain is changed by shifting the
operating point towards collector current saturation ,then it is called “Forward
AGC”.


89. List the draw backs of nonkeyed AGC.
The AGC voltage developed across the peak rectifier load tends to increase during
vertical sync pulse periods because the video signal amplitude remains almost at the
peak value every time vertical sync pulses occur. This results in a 50Hz ripple over
the negative AGC voltage and reduces gain of the receiver during these intervals.The
reduced gain results in weak vertical sync pulse which in turn can put the vertical
deflection oscillator out of synchronism causing rolling of the picture.

90. Merits of Keyed AGC system.
           AGC voltage developed is a true representation of the peak of fixedsync
           level and thus corresponds to the actual incoming signal strength.
           Noise effects are minimized because conduction is restricted to a small
           fraction of the total line period.


91. Write short notes on CATV.
            CATV stands for community antenna television systems. The CATV
    system is a cable system distributes good quality television signal to a very large
    number of receivers throughout an entire community. Generally this system gives
    increased TV programmes to subscribers who pay a fee for this service. A cable
    system may have many more active VHF and UHF channels than a receiver tuner
    can directly select.

   .

92. What do you understand by satellite TV?
            Satellite TV is a TV from space. Broadcasters from earth transmit their
    programmes to specified satellites. Then, the transmissions are returned to
    receiving equipment on the ground. Therefore, the better the receiving equipment
    ,the higher the quality of the reception.

93. List some of the applications of satellite TV?
            The shear range of programmes currently available on satellite channel is
    very much impressive such as 24-hour music videos, news, and feature films. A
    variety of general entertainment programmes, sports ,children’s programmes ,
    foreign language broadcasts and cultural programmes are all available for the
    keyboard dish owner. Some of these come through subscription channels and
    others by free to watch channels which are sponsored by advertising.

94. State the merits of satellite TV.




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            The picture quality from satellite systems is surprisingly good and
   compares well with conventional land based TV transmissions. In addition unlike
   terrestrial broadcasts it is free from the spectrum of picture ghosting.

95. Mention the limitations of satellite TV.
           The limitation of the satellite TV is varying picture and audio quality .By
    adopting de-emphasis circuits we can avoid the variations.

96. Give the applications of video tape recorders.
            Smaller and lower priced video tape recorders using ½ inch tape are
    available for closed type circuit TV or for use in the home. They can record and
    playback programs on a television receiver in color and monochrome. In addition
    to that small portable cameras are provided for a complete television system with
    the recorder. These portable systems are also employed for taping television
    programs from a remote are also employed for taping television programs from a
    remote location for away from the TV broadcast studio.

97. List some merits of high definition television.
           Improvement in both vertical and horizontal resolution of the reproduced
           picyure by approximately 2:1 over existing standards.
           Much improved colour rendition
           Higher aspect ratio of atleast 5:3
           Stereophonic sound

98. What do you mean by Longitudinal video recording?
            A method in which video signals are recorded on atleast several tracks
    along the length of the tape.

99. What do you mean by Quadruplex (Transverse) scan recording?
           In transverse scan recording ,four recording heads are spaced 90 apart and
    are mounted on a rotating drum and the tape moves past it,transversely.Each head
    comes in contact with the tape as the previous one leaves it.

100.      What do you mean by helical scan recording ?
          In helical scan recording ,the two recording heads ‘look at ‘ the tape
   surface as it is drawn past them through two tiny rectangular slits mounted on
   opposite sides of the drum.The heads thus trace out diagonal tracks across the
   tape,one track per head.

101.       What are two types of video disc system?
           Laser or optical disc system
           Capacitance disc system

102.       List the fundamental components of DVD player.
           A drive motor to spin the disc.
           A laser and lens system to focus in on the bumps and read them.



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           Tracking mechanism that can move the laser assembly so that the lasers
           beam can follow the spiral track.
           Electronic circuitry

103.      What are the advantages of DVD players over VCR’s.
          The quality of picture and sound in a DVD is better than on a video
   tape,and DVD’s maintain their high quality over time,because there is no
   physical contact with the disc as it revolves.

104.       List 4 merits of digital TV receivers.
               o Reduced Ghosts
               o Reduction of 50Hz flicker
               o High resolution pictures
               o Slow motion action




                                    PART B
1. Describe how the flicker is solved by interlaced scanning?

   Interlaced Scanning
           Effective rate of 50 vertical scans per second is utilized to reduce the
           flicker.
           Increase the downward rate of travel of the scanning electron beam.
           Every alternate line gets scanned instead of every successive line.
   Scanning Periods
           Duration of one horizontal line is 64µs
           Duration of one vertical trace is 20ms

2. Explain the structure and the generation of video output from a vidicon camera.
      • it functions on the principle of photo conductivity
      • in photoconductive method where the conductivity or resistivity of the
          photoconductive surface varies with in proportion to the intensity of light
          focused on it.
      • With a B+ source of 40V ,an area with high illumination may attain a
          potential of about +39V on the beam side.
      • Dark areas may attain a potential of about +35 on the beam side.
      • As the beam scans the target plate, it encounters different positive
          potentials on the side of photo layer that faces the gun.
      • Number of electrons from the beam is then deposited on the photo layer
          surface to reduce to reduce the potential of each element.
      • Sudden change in potential on each element causes a current flow in the
          signal electrode circuit producing a varying voltage across the load
          resistance.



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3. Give the constructional details of a monochrome picture tube and explain the
   beam landing
           Employs electrostatic focusing and electro magnetic deflection
           Composite video signal that is injected either at the grid or cathode of the
           tube
   Electron Gun:-emits the electron beam with proper energy to cause it to fluoresce,
   another anode called final anode is included within the tube.
   Low Voltage Focusing:
           It needs less voltage at the focusing electrodes.
   High Voltage Focusing:
           It requires high voltage at the focusing electrode. This focus system is
   called ‘unipotential lens’ system.
   Picture Tube Screen:
           Screen phosphor: -light metals such as zinc and cadmium in the form of
   sulphide, sulphate, and phosphor compounds are used.
           Screen Brightness:-picture tubes employ a very thin coating of aluminium
   on the back surface of the screen .This improves the screen brightness.



4. Explain in detail the silicon diode array vidicon camera tube.
   It uses photovoltaic type where the target is prepared from a thin n-type silicon
   wafer instead of deposited layers on the glass faceplate.
           Oxidation:-to form a film of silicon dioxide(Sio2)which is an insulator.
           Photomasking and etching: - an array of fine openings is made in the
           Oxide layer.
           Boron is vapourized through the array of holes.
           Thin layer of gold is deposited on each p type opening to form contacts for
           signal output.

           The silicon target plate thus formed is typically 0.003cm thick,1.5 cm
           square having an array of 540x540 photodiodes.
           The Target plate is mounted in a vidicon type of camera tube.


5. Write notes on composite video signal.
          Composite video signal consists of a camera signal, blanking pulses
          and synchronizing pulses.
          The difference between the black level and blanking level is known
          as the pedestal.
          The peak-white level is defined as the level of the video signal
          when the picture detail being transmitted corresponds to the
          maximum whiteness to be handled
          Pedestal height is the distance between the pedestal level and the
          average value axis of the video signal.




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           The composite video signal consist of blanking pulses to make the
           retrace lines invisible by increasing the signal amplitude little above
           the black level of 75percent during the time scanning the circuits
           develop retrace.
           To rectify the drawback which occurs on account of half-line
           discrepancy five narrow pulses are added on either side of the
           vertical sync pulse. These are called pre-equalising        and post-
           equalising pulses .


6. Draw Block Diagram of RF Tuner and explain how incoming signals from
   different sections are translated to common picture IF and sound IF frequencies.
           RF tuner section consists of RF amplifier ,mixer and local oscillator and is
           normally mounted on a separate subchasis,called the front end.
           The purpose tuner unit is to amplify both picture and sound signals picked
           up the antenna and to convert the carrier frequencies and their associated
           side bands into intermediate frequencies.
           The receiver uses superheterodyne principle.The signal voltage or
           information from various stations modulated over different carrier
           frequencies is heterodyned in the mixer with the output from a local
           oscillator to transfer original information on a common fixed carrier
           frequency called intermediate frequency(IF)
           The setting of local oscillator frequency enables selection of desired
           station.

7. Describe briefly the factors that influenced the choice of picture IF =38.9 and
   sound IF =33.4MHz in the 625 line system.
   The factors that influence the choice of intermediate frequencies in TV receivers
   are:
          Image Rejection Ratio:
              Image rejection ratio is defined as the output due to desired station
          divided by output due to image signal.
          Pickup due to local oscillator radiation from TV receivers
          Image Frequencies should not lie in the FM band
          Interference or direct pickup from bands assigned for other services
          Gain

8. Explain how composite video signal is detected ?How is the polarity of video
   output signal decided?
          Modulated IF signals after due amplification in the IF section are fed to
          the video detector .
          The video detector is designed to recover composite video signal and to
          transform the sound signal to another lower carrier frequency.
          This is done by rectifying the input signal and filtering out unwanted
          frequency components.




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           A diode is used ,which is suitably polarized to rectify either positive or
           negative peaks of the input signal.

9. Draw block diagram of a monochrome TV receiver and briefly explain the
   operation of TV receiver.
           A black and white receiver has six main sections:-
   Tuner section, IF sub system ,Video section ,Audio section, Deflection and power
   supply.
   Tuner section:
   This section consists of RF amplifier ,mixer and local oscillator.It selects the
   desired channel signal from those picked up by the antenna and converts it into
   the IF band.
   IF subsystem:
   The IF subsystem includes IF section ,AGC circuit and video detector.The IF
   section provides large amplification to the weak IF signals and the video detector
   that follows IF amplifiers produces composite video and intercarrier FM sound
   signals.
   Video section:
   The Video signal is accorded large amplification and fed to the picture tube.
   Audio section:
   The sound associated with the picture is transmitted as an FM signal with a center
   frequency 5.5MHz above the station picture carrier frequency. The sound signal
   BW is only about 150Khz as compared to the large bandwidth of 5MHz for the
   picture signal.
   Sync separation and processing:
   The horizontal and vertical sync pulses that form part of the composite video
   signal are separated in the sync separator. The composite video signal is either
   taken from the video detector output or after one stage of video amplification.
   DC power supplies:
   All the active devices ,ICs and picture tube need a dc source for their operation.
   Rectifiers are used to convert ac to dc and filters provided to eliminate ac ripple in
   the dc output.

10. Explain briefly the operation of IF subsystem.
            The IF subsystem          includes IF section ,AGC circuit and video
    detector.The IF section provides large amplification to the weak IF signals and the
    video detector that follows IF amplifiers produces composite video and
    intercarrier FM sound signals.
    The factors that influence the choice of intermediate frequencies in TV receivers
    are:
            Image Rejection Ratio:
                Image rejection ratio is defined as the output due to desired station
            divided by output due to image signal.
            Pickup due to local oscillator radiation from TV receivers
            Image Frequencies should not lie in the FM band
            Interference or direct pickup from bands assigned for other services



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                 Gain
         IF section :
                 The main function of this section is to amplify modulated IF signal over
                 its bandwidth with an input of about 0.5mV signal from the mixer to
                 deliver about 4V into the video detector.
                 IF section is used to equalize amplitudes of sideband components ,because
                 of vestigial side band transmission.
                 IF section is used to reject the signals from adjacent channels.

11.      Explain in detail the NTSC color receiver system.

                 NTSC system is compatible with 525 line American system.In order to
         maintain compatibility two new colour difference signals are generated and they
         are represented as I and Q. Since eye is capable of resolving finer details in the
         regions around I,it is allowed to have a maximum bandwidth of 1.5MHz.The
         bandwidth of Q signal is restricted to 0.5MHz.
         Limitations of the NTSC system.
         The NTSC system is sensitive to transmission path differences which introduces
         phase errors that result in colour changes in the picture. At the transmitter,phase
         changes in the chroma signal take place when change over between programmes
         of local and television network systems takes place and when video tape recorders
         are switched on .The phase angle is also affected by the level of the signal while
         passing through various circuits .In addition cross talk between demodulator
         outputs at the receiver causes colour distortion.

      12. Explain working of a pAL system.
                 The weighted (B-Y) and (R-Y) signals are modulated without being given
                 a phase shift of 33 as is done in the NTSC system.
                 On modulation both the color difference signals are allowed the same
                 bandwidth of about 1.3MHz.
                 The color subcarrier frequency is chosen to be 4.43MHz.
                 The weighted color difference signals are quadrature modulated with the
                 subcarrier.
       13.Describe with necessary diagrams the encoding of color difference signal.
          Quadrature modulation:
                 It is used to combine two colour difference signals in to a single variable.
          Frequency interleaving:
                 The technique of combining two distinct signal within the same bandwidth
                 is known as frequency interleaving.
          Colour burst:
                 Sample of colour subcarrier output at the encoder are transmitted along
                 with other sync pulses.
      14.Describe the generation of Y signal and color difference signals.
          Find the value for cyan.
                 In a color camera ,the luminance or Y signal is obtained by adding R,G
                 and B in the following proportions



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           Y=0.30R+0.59G+0.11B.
15.Explain in detail about SECAM system.
   SECAM color system is compatible wit819 line monochrome system.
           The difference between the SECAM system on one hand and NTSC and
   PAL on the other is that the later transmit and receive two chrominance signals
   simultaneously while in the SECAM system only one of the two color difference
   signal is transmitted at a time.
                   In SECAM system, the chrominance signals are pre-emphasized
   before modulation. After modulating the carrier with the pre-emphasized and
   weighted color difference signals, another form of preemphasis is carried out on
   the signals. This takes the form of increasing amplitude of the sub carrier as its
   deviation increases. Such a preemphasis is called high frequency preemphasis.

16.Explain the working of U and V demodulators.
           The chrominance available at the output of delay line circuitry consists of
           two suppressed carrier amplitude modulated components designated as U
           and V.
           These correspond to the two color difference signal and bear information
           about their amplitude and polarity
           Because of quadrature modulation ,the two modulation product signals
           have a phase difference of 90 at any instant with respect to each other.

           Thus when one is passing through its positive or negative peak, the other
           is passing through Zero.
           The demodulating devices are normally biased to cutoff and conduct only
           at positive peaks of the externally fed subcarrier which is large in
           amplitude.

17.Describe with a circuit Burst phase discriminator.
   The burst seperator circuit has the function of extracting 8 to 10 cycles of
   reference color burst which are transmitted on the back porch of every horizontal
   pulse. The circuit is tuned to the subcarrier frequency and is keyed on during the
   flyback time by pulses derived from the horizontal output stage.


18.Write the need and working of Automatic Gain control Circuit.
           AGC circuit controls the gain of RF and IF stage to enable almost constant
   signal voltage at the output of video detector, despite changes in the signal picked
   up by the antenna. The change in gain is achieved by shifting the operating point
   of transistors used in the amplifiers. The operating point is changed by a bias
   voltage that is developed in the bias circuit.

19.Write Short notes on color killer circuit.
           When a monochrome transmission is received there is no input to the color
   killer and no positive voltage is developed . Therefore no input is given to the




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   second chroma amplifier from the color killer circuit ,it blocks the second chroma
   amplifier.Thus it prevents the color noise on black and white picture.

20.Briefly explain PAL-D system.
   The use of eye as the averaging mechanism for the correct hue is the basic
   concept of simple ‘PAL’ system. Beyond a certain limit , the human eye see the
   effect of colour changes on alternate lines hence the system needs modification.
   Considerable improvement found in the system of a delay line is used to do the
   averaging first and then present the color to the eye.This is called PAL-D or delay
   line PAL method and is most commonly employe in PAL receivers.

21.Briefly explain satellite based TV broadcast system.
           Satellite TV is a TV from space. Broadcasters from earth transmit their
   programmes to specified satellites. Then, the transmissions are returned to
   receiving equipment on the ground. Therefore, the better the receiving equipment
   ,the higher the quality of the reception.
   Applications of satellite TV:
           The shear range of programmes currently available on satellite channel is
   very much impressive such as 24-hour music videos, news, and feature films. A
   variety of general entertainment programmes, sports ,children’s programmes ,
   foreign language broadcasts and cultural programmes are all available for the
   keyboard dish owner. Some of these come through subscription channels and
   others by free to watch channels which are sponsored by advertising.
    Limitation:
   The limitation of the satellite TV is varying picture and audio quality .By
   adopting de-emphasis circuits we can avoid the variations.

22.Write short notes on Video disc system.
            The video disc is essentially a gramophone record with pictures on it.The
   first video disc was the laser optical and the second video disc system is based on
   the capacitance principle.


23.Write short notes on High definition Television.
    It aims at
            Improvement in both vertical and horizontal resolution of the reproduced
            picyure by approximately 2:1 over existing standards.
            Much improved colour rendition
            Higher aspect ratio of atleast 5:3
            Stereophonic sound
24. Briefly explain CATV system.
25. Briefly explain Digital TV transmission and reception.




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VLSI DESIGN




              111
                           EC1401 – VLSI Design
                    2 Marks - Question and Answers

Unit I


1.   What is Intrinsic and Extrinsic Semiconductor?
     The pure Silicon is known as Intrinsic Semiconductor.
     When impurity is added with pure Silicon, its electrical properties are varied.
     This is known as Extrinsic Semiconductor.


2.   What is CMOS Technology?
     The fabrication of an IC using CMOS transistors is known as CMOS Technology.
     CMOS transistor is nothing but an inverter, made up of an n-MOS and p-MOS
     transistor connected in series.

3.   Give the advantages of CMOS IC?
            • Size is less
            • High Speed
            • Less Power Dissipation

4.   What are four generations of Integration Circuits?
           • SSI (Small Scale Integration)
           • MSI (Medium Scale Integration)
           • LSI (Large Scale Integration)
           • VLSI (Very Large Scale Integration)


5.   Give the variety of Integrated Circuits?
            • More Specialized Circuits
            • Application Specific Integrated Circuits (ASICs)
            • Systems-On-Chips


6.   Why NMOS technology is preferred more than PMOS technology?
     N-channel transistors have greater switching speed when compared to PMOS
     transistors. Hence, NMOS is preferred than PMOS.


7.   What are the different MOS layers?
         •   n-diffusion
         •   p-diffusion
         •   Polysilicon
         •   Metal
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8.    What are the different layers in MOS transistor?
      The layers are Substrate, diffused Drain & Source, Insulator (SiO2) & Gate.




9.    What are the different operating regions for an MOS transistor?
         •   Cutoff Region
         •   Non- Saturated (Linear) Region
         •   Saturated Region


10.   What is Enhancement mode transistor?
      The device that is normally cut-off with zero gate bias is called Enhancement
      mode transistor.


11.   What is Depletion mode device?
      The Device that conducts with zero gate bias is called Depletion mode device.


12.   When the channel is said to be pinched off?
      If a large Vds is applied, this voltage will deplete the inversion layer. This Voltage
      effectively pinches off the channel near the drain.


13.   What are the steps involved in manufacturing of IC?
             •   Silicon wafer Preparation
             •   Epitaxial Growth
             •   Oxidation
             •   Photo-lithography
             •   Diffusion
             •   Ion Implantation
             •   Isolation technique
             •   Metallization
             •   Assembly processing & Packaging
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14.   What is meant by Epitaxy?
      Epitaxy means arranging atoms in single crystal fashion upon a single crystal
      substrate.


15.   What are the processes involved in photo lithography?
      (1) Masking process
      (2) Photo etching process.
      These are important processes involved in photolithography.


16.   What is the purpose of masking in fabrication of IC?
      Masking is used to identify the location in which Ion-Implantation should not take
      place.


17.   What lire the materials used for masking?
      Photo resist, Si02, SiN, Poly Silicon.


18.   What are the types of Photo etching?
      Wet etching and dry etching are the types of photo etching.


19.   What is diffusion process? What are doping impurities?
      Diffusion is a process in which impurities are diffused into the Silicon chip at
      1000˚C temperature. B203 and P205 are used as impurities used.


20.   What is Ion-Implantation process?
      It is process in which the Si material is doped with an impurity by making the
      accelerated impurity atoms to strike the Si layer at high temperature.

21.   What are the various Silicon wafer Preparation?
            • Crystal growth & doping
            • Ingot trimming & grinding
            • Ingot slicing
            • Wafer polishing & etching
            • Wafer cleaning.


22.   What are the different types of oxidation?
      The two types of oxidation are Dry & Wet Oxidation.

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23.   What is Isolation?
      It is a process used to provide electrical isolation between different components
      and interconnections.


24.   Give the different types of CMOS process?
         •   p-well process
         •   n-well process
         •   twin-tub process
         •   SOI process


25.   What is Channel-stop Implantation?
      In n-well fabrication, n-well is protected with the resist material. (Because, it
      should not be affected during Boron implantation). Then Boron is implanted
      except n-well. The above said process is done using photo resist mask. This type
      of implantation is known as Channel-stop implantation.


26.   What is LOCOS?
      LOCOS mean Local Oxidation of Silicon. This is one type of oxide construction.


27.   What is SWAMI?
      SWAMI means Side Wall Masked Isolation. It is used to reduce bird's beak effect.


28.   What is LDD?
      LDD means Lightly Doped Drain Structures.
      It is used for implantation of n- region in n-well process.


29.   What is Twin-tub process? Why it is called so?
      Twin-tub process is one of the CMOS technologies. Two wells (the other name
      for well is Tub) are created in this process. So, because of these two tubs, this
      process is known as Twin-tub process.


30.   What are the steps involved in twin-tub process?
         •   Tub Formation
         •   Thin-oxide Construction
         •   Source & Drain Implantation
         •   Contact cut definition
         •   Metallization.
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31.   What are the special features of Twin-tub process?
      In Twin-tub process, Threshold voltage, body effects of n and p devices are
      independently optimized.


32.   What are the advantages of Twin-tub process?
      Advantages of Twin-tub process are
      (1) Separate optimized wells are available.
      (2) Balanced performance is obtained for n and p transistors.


33.   What is SOI? What is the material used as Insulator?
      SOI means Silicon-on-Insulator.
      In this process, a Silicon based transistor is built on an insulating material like
      Sapphire or SiO2.


34.   What are the advantages and disadvantages of SOI process?
      Advantages of SOI process:
      1. There is no well formation in this process.
      2. There is no field-Inversion problem.
      3. There is no body effect problem.
      Disadvantages of SOI process:
      1. It is very difficult to protect inputs in this process.
      2. Device gain is low.
      3. The coupling capacitance between wires always exists.


35.   What are the advantages of CMOS process?
         •   Low Input Impedance
         •   Low delay Sensitivity to load.



36.   What are the various etching processes used in SOI process?

      Various etching processes used in SOI are,




                              (A. FULLY ANISTROPHIC ETCHING)
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                             (B. PREFERENTIAL ETCHING)




                           (C. ISOTROPHIC ETCHING)




37.   What is BiCMOS Technology?
      It is the combination of Bipolar technology & CMOS technology.


38.   What are the basic processing steps involved in BiCMOS process?
      Additional masks defining P base region
         • N Collector area
         • Buried Sub collector (SCCD)
         • Processing steps in CMOS process


39.   What is meant by interconnect? What are the types are of interconnect?
      Interconnect means connection between various components in an IC.
      Types of Inter connect:
      1. Metal Inter connect
      2. PolySilicon Inter connect
      3. Local Inter connect.


40.   What is Silicide?
      The combination of Silicon and tantaleum is known as Silicide.
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      It is used as gate material in Polysilicon Interconnect.
41.   What is Polycide?
      The combination of Silicide and Polysilicon is known as Polycide.
      It is used as gate material.


42.   What is Stick diagram?
      The diagram which conveys the layer information through the use of various
      colours is known as Stick diagram. It is also the cartoon of a chip layout.


43.   What are the uses of Stick diagram?
         •   It can be drawn much easier and faster than a complex layout.
         •   These are especially important tools for layout built from large cells.


44.   Give the various color coding used in stick diagram?
         •   Green - n-diffusion
         •   Red - polysilicon
         •   Blue - metal
         •   Yellow - implant
         •   Black - contact areas.


45.   Compare between CMOS and bipolar technologies.

                   CMOS Technology                          Bi-polar Technology
             •   Low static power dissipation           •   High power dissipation
             •   High input impedance                   •   Low input impedance
                 (low drive current)                        (high drive current)
             •   Scalable threshold voltage             •   Low voltage swing logic
             •   High noise margin                      •   Low packing density
             •   High packing density                   •   Low delay sensitivity to load
             •   High delay sensitivity to load         •   High output drive current
                 (fanout limitations)                   •   High gm (gm a eVin)
             •   Low output drive current               •   High ft at low current
             •   Low gm (gm α Vin)                      •   Essentially unidirectional
             •   Bidirectional capability
             •   A near ideal switching device



46.   Define Threshold voltage in CMOS?
      The Threshold voltage, VT for a MOS transistor can be defined as the voltage
      applied between the gate and the source of the MOS transistor below which the
      drain to source current, IDS effectively drops to zero.
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47.   What is Body effect?
      The threshold voltage VTh is not a constant with respect to the voltage difference
      between the substrate and the source of MOS transistor. This effect is called
      substrate-bias effect or body effect.


48.   What is Channel-length modulation?
      The current between drain and source terminals is constant and independent of the
      applied voltage over the terminals. This is not entirely correct. The effective
      length of the conductive channel is actually modulated by the applied VDS,
      increasing VDS causes the depletion region at the drain junction to grow, reducing
      the length of the effective channel.


49.   What is Latch – up?
      Latch-up is a condition in which the parasitic components give rise to the
      establishment of low resistance conducting paths between VDD and VSS with
      disastrous results. Careful control during fabrication is necessary to avoid this
      problem.


50.   What is demarcation line?
      Demarcation line is an imaginary line used in stick diagram, to separate p-MOS
      and n-MOS transistors.

      All p-MOS transistors are placed above demarcation line and n-MOS below the
      demarcation line




51.   What are the two types of Layout design rules?
      Lambda design rules and micron rules are major types of layout design rules.


52.   What is Lay-out design rule?
                                    the photo mask are known as Layout design rules.
      The rules followed to preparehttp://tamiltel.tk                                      119
53.   What are LVS and DRL tools?
      LVS means Layout Versus Schematic.
      It checks layout against schematic diagram. It is very important to verify layout.
      DRC means Design Rule Checker.
      This tool checks every occurrence of design rule list on layout.
      Width, spacing of every metal line in layout are checked with this tool.


54.   What is instance? What is instancing?
      To construct big complex circuit, the basic cells (small cells) can be copied. This
      process is known as Instancing. The cell which is copied is known as Instance.


55.   What is flat cell?
      The cell which is independent and not related to other objects is known as flat cell.


56.   What are the cells available in primitive library?




             NOT, NAND, NOR, are the basic cells in primitive library.



57.   What is Design Hierarchy?
      When we want to design AND-4 input gate, we use NAND-2 and NOR-2 basic
      blocks. By combining NAND-2 and NOR-2, we create AND-4 input gate. This is
      known as Design Hierarchy.




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Unit – II


1.     Draw the symbol of n-MOS and p-MOS.




       Three terminals are shown here.



2.     Draw the characteristics graph of enhancement mode of n-MOS.




                                                           When Vgs = 0;
                                                           the device will be cut-off.




3.     Draw the graph of n-MOS depletion mode.




                                                        The device will conduct;
                                                        Even if Vgs = 0.

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4.   Draw the graph of p-MOS enhancement mode.

                                                    Vos = gate-to-source voltage
                                                    Ids = drain-to-source current
                                                    Vtp = Threshold voltage
                                                          of a p-MOS transistor

                                                    If Vgs crosses Vtp;
                                                    then device will conduct.




5.   Draw the graph of p-MOS depletion mode characteristics.

                                                    Vos = gate-to-source voltage
                                                    Ids = drain-to-source current
                                                    Vtp = Threshold voltage
                                                          of a p-MOS transistor


                                                    Even if Vgs = 0;
                                                    the device will be conducting.




6.   What are the three modes in an enhancement MOS transistor?
     The different modes are    a) Accumulation mode
                                b) Inversion Mode
                                c) Depletion Mode


7.   Draw the diagram for Accumulation mode.




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8.    Draw the diagram of depletion mode in MOS Transistor.




9.    How an Inversion layer is formed in MOS Transistor?

      In Inversion mode, the gate is applied with voltage larger than its threshold
      voltage (Vgs>Vth).




      As the gate voltage is increased, the electrons in the substrate are attracted towards
      the region below the gate, pushing the holes to other side of the substrate. Thus, a
      layer of electrons is formed below the gate, which is called as Inversion layer.

      These electrons constitute the channel for conduction between source and drain.



10.   What are the different regions that can be defined in n-MOS depending upon
      the voltages applied?

      Case (1) Cut-off Region                   :           Vds = 0.
      Case (2) Non-Saturated (or) Linear region :           Vds < (Vgs – Vth)
      Case (3) Saturated Region                 :           Vgs > Vth
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11.   What is the relationship between mobility and electric field?




12.   What is Impact Ionization?
      When gate length of MOS transistor is reduced, electric field at the drain of the
      transistor (in saturation) is increased.

      In submicron technology, the field is high, so, electrons are imparted with enough
      energy to become 'hot'. These hot electrons impact the drain, and remove the holes
      from that place and then swept towards the negatively charged substrate and
      appear as a substrate current. This is known as 'Impact Ionization'.


13.   Draw the DC transfer characteristics curve to show its various regions.




14.   Draw the graph of Vout Vs Vin for various βn / βp ratio.




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15.   Define Noise Margin.
      The parameter which gives the quantitative measure of how stable the inputs are
      with respect to coupled electromagnetic signal interference.

      NML = | VIL – VOL |
      NMH = | VIH – VOH |


16.   What is full-rail output?
      Logic swing VL is defined as VL = VOH - VOL = VDD, VL = VDD




      VL = VDD = full value of power supply. This is known as full rail output.



17.   Define Fall time.
      The time needed for Vout to fall from 0.9 VDD to 0.1 VDD is known as Fall time.




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18.   Define Rise Time.
      The time needed for Vout to rise from 0.1 VDD to 0.9 VDD is known as Rise time.




19.   What is Maximum signal frequency?
      It is defined as the largest frequency (f) applied to gate and allow the output to
      settle to a definable state.

                     1
             f = -----------
                  tr + tf
                                     where, tr - Rise time
                                            tf - fall time
                                            f - maximum signal frequency


20.   Define Delay time
      Delay time, td is the time difference between input transition (50%) and the 50%
      output level. This is the time taken for a logic transition to pass from input to
      output.


21.   Define propagation Delay.
      It is defined as average of two time intervals.




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22.   What are two components of Power dissipation?
      There are two components that establish the amount of power dissipated in a
      CMOS circuit.

      These are:   i) Static dissipation due to leakage current or other current drawn
                       continuously from the power supply.
                   ii) Dynamic dissipation due to
                       • Switching transient current
                       • Charging and discharging of load capacitances.



23.   What is the formula for power dissipation for CMOS Inverter?




24.   Draw the symbol and switching model of Transmission gate.




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25.   Draw the Symbol of Tri-state Inverter.




26.   What is the fundamental goal in Device modeling?
      To obtain the functional relationship among the terminal electrical variables of the
      device that is to be modeled.


27.   Define Short Channel devices?
      Transistors with Channel length less than 3- 5 microns are termed as Short
      channel devices. With short channel devices the ratio between the lateral &
      vertical dimensions are reduced.


28.   What is pull-down device?
      A device connected so as to pull the output voltage to the lower supply voltage
      usually 0V is called pull down device.


29.   What is pull-up device?
      A device connected so as to pull the output voltage to the upper supply voltage
      usually VDD is called pull up device.


33.   Give the basic inverter circuit.




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Unit – III:


1.     Give some of the important CAD tools.
       Some of the important CAD tools are:
       i) Layout editors
       ii) Design Rule checkers (DRC)
       iii) Circuit extraction


2.     What is meant by HDL?
       It means Hardware Description Language.
       It is used to model digital circuit design.


3.     What is Verilog?
       Verilog is a general purpose hardware descriptor language. It is similar in syntax
       to the C programming language. It can be used to model a digital system at many
       levels of abstraction ranging from the algorithmic level to the switch level.


4.     What are the data types in Verilog?
       Net type: It represents physical connection between structural elements.
       Register type: It represents data storage elements.


5.     What is wire in Verilog?
       It is one of the net type. If S is the output of one gate, and input of the next block;
       S should be mentioned as wire.


6.     What is the use of parameter?
       It is a constant used to specify delays and widths of variable.
       Eg. Parameter BIT = 1, BYTE = 8;


7.     What is Time Register?
       It is used to store and manipulate time values.
       Eg. Time current time;         // current time holds one time value.




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8.    How to specify nMOS in Verilog?




                                                Syntax: nMOS n, (o/p, i/p, control).




9.    What is Gate Delay?
      The signal propagation delay from the gate i/p to the gate o/p is specified by using
      gate delay.

      Eg: nand #2 (c, a, b):
      Here; Rise delay = 2 and fall delay = 2.


10.   What is RTL?
      RTL means Register-Transfer Modeling.


11.   Give the examples for procedural statement.
      Loop statement
      Wait statement
      Conditional statement
      Case statement
      are some of the examples for procedural statement.


12.   What are the types of conditional statements?
      1. If statement (with no else)
               Syntax : if ( [expression] ) true – statement;
      2. If Statement (with One else statement)
               Syntax : if ( [expression] ) true – statement;
                        else false-statement;
      3. Nested if-else-if
               Syntax : if ( [expression1] ) true statement 1;
                        else if ( [expression2] ) true-statement 2;
                        else if ( [expression3] ) true-statement 3;
                        else default-statement;

      The [expression] is evaluated. If it is true (1 or a non-zero value) true-statement is
      executed. If it is false (zero) or ambiguous (x), the false-statement is executed.
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13.   What are the various modeling used in Verilog?
             1. Gate-level modeling
             2. Data-flow modeling
             3. Switch-level modeling
             4. Behavioral modeling

14.   What is the structural gate-level modeling?
      Structural modeling describes a digital logic networks in terms of the components
      that make up the system. Gate-level modeling is based on using primitive logic
      gates and specifying how they are wired together.


15.   What is Switch-level modeling?
      Verilog allows switch-level modeling that is based on the behavior of MOSFETs.
      Digital circuits at the MOS-transistor level are described using the MOSFET
      switches.


16.   What are identifiers?
      Identifiers are names of modules, variables and other objects that we can reference
      in the design.

      Identifiers consists of upper and lower case letters, digits 0 through 9, the
      underscore character(_) and the dollar sign($). It must be a single group of
      characters.

      Examples: A014, a, b, in_o, s_out, etc.



17.   What are the value sets in Verilog?
      Verilog supports four levels for the values needed to describe hardware referred to
      as value sets.

      Value levels   Condition in hardware circuits
             0       Logic zero, false condition
             1       Logic one, true condition
             X       Unknown logic value
             Z       High impedance, floating state



18.   What are the types of gate arrays in ASIC?
      1) Channeled gate arrays
      2) Channel less gate arrays
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19.   Give the classifications of timing control.
      Methods of timing control:
      1. Delay-based timing control
      2. Event-based timing control
      3. Level-sensitive timing control
      Types of delay-based timing control:
      1. Regular delay control
      2. Intra-assignment delay control
      3. Zero delay control
      Types of event-based timing control:
      1. Regular event control
      2. Named event control
      3. Event OR control
      4. Level-sensitive timing control


20.   Give the different arithmetic operators.
      Operator symbol       Operation performed         Number of operands
             *               Multiply                      Two
             /               Divide                        Two
             +               Add                           Two
             -               Subtract                      Two
             %               Modulus                       Two
             **              Power (exponent)              Two


21.   Give the different bitwise operators.
      Operator symbol       Operation performed         Number of operands
             ~               Bitwise negation              One
             &               Bitwise AND                   Two
             |               Bitwise OR                    Two
             ^               Bitwise XOR                   Two
             ^~ or ~^        Bitwise XNOR                  Two
             ~&              Bitwise NAND                  Two
             ~|              Bitwise NOR                   Two



22.   Write the program for OR gate using Dataflow modeling.
             module or gate (c, a, b)
                   input a;
                   input b;
                   output c;
                   assign c = a/b;
             end module.

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23.   What are gate primitives?
      Verilog supports basic logic gates as predefined primitives. Primitive logic
      function keyword provide the basics for structural modeling at gate level. These
      primitives are instantiated like modules except that they are predefined in Verilog
      and do not need a module definition. The important operations are AND, NAND,
      OR, XOR, XNOR, and BUF (non-inverting drive buffer).



24.   What are resistive primitives?
      rnMOS, rpMOS, rcMOS are some of the resistive primitives.



25.   Give the two blocks in behavioral modeling.
      1. An initial block    executes once in the simulation and is used to set up initial
                             conditions and step-by-step data flow.
      2. An always block     executes in a loop and repeats during the simulation.



26.   Name the types of ports in Verilog
      Types of port         Keyword
      Input port             Input
      Output port            Output
      Bidirectional port     Input



27.   Initialize port A as input, port b as output, and port c as inout port.
             module name (a, b, c)
             input a ;
             output b;
             inout c;


28.   What are the types of procedural assignments?
      1. Blocking assignment
      2. Non-blocking assignment


29.   Give the different symbols for transmission gate.




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Unit – IV:


1.    Give the different types of ASIC.
      1. Full custom ASICs
      2. Semi-custom ASICs
              * Standard cell based ASICs
              * Gate-array based ASICs
      3. Programmable ASICs
              * Programmable Logic Device (PLD)
              * Field Programmable Gate Array (FPGA).


2.    What is the full custom ASIC design?
      In a full custom ASIC, an engineer designs some or all of the logic cells, circuits
      or layout specifically for one ASIC. It makes sense to take this approach only if
      there are no suitable existing cell libraries available that can be used for the entire
      design.


3.    What is the standard cell-based ASIC design?
      A cell-based ASIC (CBIC) uses pre-designed logic cells known as standard cells.
      The standard cell areas also called fle4xible blocks in a CBIC are built of rows of
      standard cells. The ASIC designer defines only the placement of standard cells
      and the interconnect in a CBIC. All the mask layers of a CBIC are customized and
      are unique to a particular customer.


4.    Differentiate between channeled & channel less gate array.
               Channeled Gate Array                             Channel less Gate Array
       1. Only interconnect is customized.               Only the top few mask layers are
                                                         customized.
       2. The interconnect uses predefined               No predefined areas are set aside for
          spaces between rows of base cells.             routing between cells.
       3. Routing is done using the spaces.              Routing is done using the area of
                                                         transistors unused.
       4. Logic density is less.                         Logic density is higher.




5.    What is a FPGA?
      A field programmable gate array (FPGA) is a programmable logic device that
      supports implementation of relatively large logic circuits. FPGAs can be used to
      implement a logic circuit with more than 20,000 gates whereas a CPLD can
      implement circuits of upto about 20,000 equivalent gates.
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6.    Give the constituent of I/O cell in 22V10.
      2V10 I/O cell consists of
      1. a register
      2. an output 4:1 mux
      3. a tristate buffer
      4. a 2:1 input mux

      It has the following characteristics:
      * 12 inputs
      * 10 I/Os
      * product time 9 10 12 14 16 14 12 10 8
      * 24 pins


7.    What are the different methods of programming of PALs?
      The programming of PALs is done in three main ways:
      • Fusible links
      • UV – erasable EPROM
      • EEPROM (E2PROM) – Electrically Erasable Programmable ROM


8.    What is an antifuse?
      An antifuse is normally high resistance (>100MW). On application of appropriate
      programming voltages, the antifuse is changed permanently to a low-resistance
      structure (200-500W).


9.    What are the different levels of design abstraction at physical design?
             • Architectural or functional level
             • Register Transfer-level (RTL)
             • Logic level
             • Circuit level

10.   What are macros?
      The logic cells in a gate-array library are often called macros.


11.   What are Programmable Interconnects?
      In a PAL, the device is programmed by changing the characteristics if the
      switching element. An alternative would be to program the routing.




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12.   Give the steps in ASIC design flow.
      a. Design entry
      b. Logic synthesis and System partitioning
      c. Pre-layout simulation.
      d. Floor planning
      e. Placement
      f. Routing
      g. Extraction
      1. Post layout simulation



13.   Give the XILINX Configurable Logic Block (CLB).




14.   Give the XILINX FPGA architecture.




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Unit – V:


1.    Mention the levels at which testing of a chip can be done?
      a) At the wafer level
      b) At the packaged-chip level
      c) At the board level
      d) At the system level
      e) In the field


2.    What are the categories of testing?
      a) Functionality tests
      b) Manufacturing tests


3.    Write notes on functionality tests?
      Functionality tests verify that the chip performs its intended function.
      These tests assert that all the gates in the chip, acting in concert, achieve a desired
      function. These tests are usually used early in the design cycle to verify the
      functionality of the circuit.


4.    Write notes on manufacturing tests?
      Manufacturing tests verify that every gate and register in the chip functions
      correctly. These tests are used after the chip is manufactured to verify that the
      silicon is intact.


5.    Mention the defects that occur in a chip?
      a) layer-to-layer shorts
      b) discontinous wires
      c) thin-oxide shorts to substrate or well


6.    Give some circuit maladies to overcome the defects?
      i. nodes shorted to power or ground
      ii. nodes shorted to each other
      iii. inputs floating/outputs disconnected


7.    What are the tests for I/O integrity?
      i. I/O level test
      ii. Speed test
      iii. IDD test
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8.    What is meant by fault models?
      Fault model is a model for how faults occur and their impact on circuits.


9.    Give some examples of fault models?
      i. Stuck-At Faults
      ii. Short-Circuit and Open-Circuit Faults


10.   What is stuck–at fault?
      With this model, a faulty gate input is modeled as a “stuck at zero” or “stuck at
      one”. These faults most frequently occur due to thin-oxide shorts or metal-to-
      metal shorts.


11.   What is meant by observability?
      The observability of a particular internal circuit node is the degree to which one
      can observe that node at the outputs of an integrated circuit.


12.   What is meant by controllability?
      The controllability of an internal circuit node within a chip is a measure of the
      ease of setting the node to a 1 or 0 state.


13.   What is known as percentage-fault coverage?
      The total number of nodes that, when set to 1 or 0, do result in the detection of the
      fault, divided by the total number of nodes in the circuit, is called the percentage-
      fault coverage.


14.   What is fault grading?
      Fault grading consists of two steps. First, the node to be faulted is selected.
      A simulation is run with no faults inserted, and the results of this simulation are
      saved. Each node or line to be faulted is set to 0 and then 1 and the test vector set
      is applied. If and when a discrepancy is detected between the faulted circuit
      response and the good circuit response, the fault is said to be detected and the
      simulation is stopped.


15.   Mention the ideas to increase the speed of fault simulation?
      a. parallel simulation
      b. concurrent simulation

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16.   What is fault sampling?
      An approach to fault analysis is known as fault sampling. This is used in circuits
      where it is impossible to fault every node in the circuit. Nodes are randomly
      selected and faulted. The resulting fault detection rate may be statistically inferred
      from the number of faults that are detected in the fault set and the size of the set.
      The randomly selected faults are unbiased. It will determine whether the fault
      coverage exceeds a desired level.


17.   What are the approaches in design for testability?
      a. ad hoc testing
      b. scan-based approaches
      c. self-test and built-in testing


18.   Mention the common techniques involved in ad hoc testing?
      a. partitioning large sequential circuits
      b. adding test points
      c. adding multiplexers
      d. providing for easy state reset


19.   What are the scan-based test techniques?
      a) Level sensitive scan design
      b) Serial scan
      c) Partial serial scan
      d) Parallel scan


20.   What are the two tenets in LSSD?
      a. The circuit is level-sensitive.
      b. Each register may be converted to a serial shift register.


21.   What are the self-test techniques?
      a. Signature analysis and BILBO
      b. Memory self-test
      c. Iterative logic array testing


22.   What is known as BILBO?
      Signature analysis can be merged with the scan technique to create a structure
      known as BILBO (Built In Logic Block Observation).


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23.   What is known as IDDQ testing?
      A popular method of testing for bridging faults is called IDDQ or current supply
      monitoring. This relies on the fact that when a complementary CMOS logic gate is
      not switching, it draws no DC current. When a bridging fault occurs, for some
      combination of input conditions a measurable DC IDD will flow.


24.   What are the applications of chip level test techniques?
      a. Regular logic arrays
      b. Memories
      c. Random logic


25.   What is Boundary scan?
      The increasing complexity of boards and the movement to technologies like multi-
      chip modules and surface-mount technologies resulted in system designers
      agreeing on a unified scan-based methodology for testing chips at the board. This
      is called Boundary scan.


26.   What is the Test Access Port?
      The Test Access Port (TAP) is a definition of the interface that needs to be
      included in an IC to make it capable of being included in a boundary-scan
      architecture.

      The port has four or five single bit connections, as follows:
      • TCK(The Test Clock Input)
      • TMS(The Test Mode Select)
      • TDI(The Test Data Input)
      • TDO(The Test Data Output)

      It also has an optional signal
      • TRST*(The Test Reset Signal)


27.   What are the contents of the test architecture?
      The test architecture consists of:
      • The TAP interface pins
      • A set of test-data registers
      • An instruction register
      • A TAP controller


28.   What is the TAP controller?
      The TAP controller is a 16-state FSM that proceeds from state to state based on
      the TCK and TMS signals. It provides signals that control the test data registers,
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      and the instruction register. These include serial-shift clocks and update clocks.
29.   What is known as test data register?
      The test-data registers are used to set the inputs of modules to be tested, and to
      collect the results of running tests.


30.   What is known as boundary scan register?
      The boundary scan register is a special case of a data register. It allows circuit-
      board interconnections to be tested, external components tested, and the state of
      chip digital I/Os to be sampled.




                       *************** X ***************




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                        BIG QUESTIONS & ANSWERS

1.   Derive the CMOS inverter DC characteristics and obtain the relationship for
     output voltage at different region in the transfer characteristics.
     Explanation (2)
     Diagram (2)
     CMOS inverter (2)
     DC characteristics (5)
     Transfer characteristics (5)

2.   Explain with neat diagrams the various CMOS fabrication technology
     P-well process (4)
     N-well process (4)
     Silicon-On-Insulator Process (4)
     Twin- tub Process (4)

3.   Explain the latch up prevention techniques.
     Definition (2)
     Explanation (2)
     Diagram (2)

4.   Explain the operation of PMOS Enhancement transistor
     Explanation (2)
     Diagram (2)
     Operation (4)

5.   Explain the threshold voltage equation
     Definition (2)
     Explanation (2)
     Derivation (4)

6.   Explain the silicon semiconductor fabrication process.
     Silicon wafer Preparation (2)
     Epitaxial Growth (2)
     Oxidation (2)
     Photolithography (2)
     Diffusion(2)
     Ion Implantation (2)
     Isolation technique (2)
     Metallization (1)
     Assembly processing & Packaging (1)

7.   Explain various CAD tool sets.
     Layout editors (4)
     Design Rule checkers (DRC) (4)
     Circuit extraction (4)



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8.    Explain the operation of NMOS Enhancement transistor.
      Explanation (2)
      Diagram (2)
      Operation (4)

9.    Explain the Transmission gate and the tristate inverter briefly.
      Explanation (2)
      Diagram (2)
      Operation (4)

10.   Explain about the various non ideal conditions in MOS device model.
      Explanation (2)
      Diagram (2)
      Operation (4)

11.   Explain the design hierarchies.
      Explanation (2)
      Diagram (2)
      Concept (2)

12.   Explain the concept involved in Timing control in VERILOG.
      Explanation (2)
      Diagram (2)
      Delay-based timing control (4)
      Event-based timing control (4)
      Level-sensitive timing control (4)

13.   Explain with neat diagrams the Multiplexer and latches using transmission Gate.
      Explanation (2)
      Diagram (2)
      Multiplexer (4)
      latches(4)

14.   Explain the concept of gate delay in VERILOG with example
      Explanation (2)
      Diagram (2)
      Concept (2)

15.   Explain the concept of MOSFET as switches and also bring the various logic
      gates using the switching concept.
      Explanation (2)
      Diagram (2)
      Gate Concepts (4)




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16.       Explain the concept involved in structural gate level modeling and also give the
          description for Half adder and Full adder.
          Explanation (2)
          Diagram (2)
          Gate Concepts (6)
          Half adder (3)
          Full adder (3)

17.       What is ASIC? Explain the types of ASIC.
          Definition (2)
          Types (2)
          Full custom ASICs (4)
          Semi-custom ASICs(4)
          Programmable ASICs(4)

18.       Explain the VLSI design flow with a neat diagram
          Explanation (2)
          Flow Diagram (2)
          Concepts (4)

19.       Explain the concept of MOSFET as switches
          Explanation (2)
          Diagram (2)
          Concepts (4)

20.       Explain the ASIC design flow with a neat diagram
          Design entry (2)
          Logic synthesis and System partitioning (2)
          Pre-layout simulation. (2)
          Floor planning (2)
          Placement (2)
          Routing (2)
          Extraction (2)
          Post layout simulation (2)

21. a) Explain fault models.
          Stuck-At Faults
                 Definition (2)
                 Diagram (2)
          Short-circuit and Open-circuit faults
                 Definition (2)
                 Diagram (2)

      b) Explain ATPG.
         Definition (2)
         Truth tables (2)
         Five valued logic (2)
         Testability measures (2)
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22.   Briefly explain
      a) Fault grading & fault simulation
              Fault grading (2)
              Fault simulation (2)
      b) Delay fault testing
              Diagram (2)
              Description (2)
      c) Statistical fault analysis
              Definition (1)
              Statistics (3)
      d) Fault sampling (4)

23.   Explain scan-based test techniques.
      Level sensitive scan design (4)
      Serial scan (4)
      Partial serial scan (4)
      Parallel scan (4)

24.   Explain Ad-Hoc testing and chip level test techniques.
      Ad-Hoc testing
      Parallel-load feature (2)
      Test signal block (2)
      Use of the bus (2)
      Use of multiplexer (2)
      Chip level test techniques
      Definition (2)
      Regular logic arrays (2)
      Memories (2)
      Random logic (2)

25.   Explain self-test techniques and IDDQ testing.
      Signature analysis and BILBO (6)
      Memory-self test (4)
      Iterative logic array testing (3)
      IDDQ testing (3)

26.   Explain system-level test techniques.
      Boundary scan – definition (2)
      The Test Access Port (2)
      The Test Architecture (2)
      The TAP Controller (3)
      The Instruction Register (2)
      Test-Data Registers (2)
      Boundary Scan Registers (3)




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COMPUTER
 HARDWARE
AND INTERFACING
           DEPARTMENT OF ELECTRONICS AND COMMUNICATION
                                   ENGINEERING

                              QUESTION BANK
SUBJECT CODE   : EC1003                        SEM / YEAR   :    VII/ IV

SUBJECT NAME    : COMPUTER HARDWARE AND INTERFACING



                                          UNIT I

                                 CPU & MEMORY

                               PART - A ( 2 marks)

  1. What are the three types of busses?
  2. What are the three types of processor modes?
  3. What is meant by circuit size and die size?
  4. Differentiate between CISC Vs RISC CPUs
  5. What is the importance of processor cooling?
  6. Write about processor packages
  7. What is the importance of over clocking?
  8. What is meant by super pipelining?
  9. What is meant by multiprocessing?
  10. Give details about memory organization?
  11. Draw the block diagram of basic memory chip?
  12. What is bursting and pipelining?

                                         PART - B

  1. Processors are capable of operating in several different modes- explain any three
     processor modes                                                              (16)
2. What are the different factors which summarize the modern concept of CPU? (16)
3. Describe the Architectural performance features?                          (16)
4. Explain the concept of CPU over clocking?                                 (16)
5. What are the five package styles normally used fro memory devices?        (16)
6. Explain the three types of memory modules?                                (16)
7. Explain the Logical memory Organization?                                  (16)
8. Explain some of the current memory architecture and major issues surround them?
                                                                              (16)
9. List out the traditional memory types and specialized memory devices.      (16)
10. Write the procedure for selecting and installing memory?                  (16)


                                      UNIT II

                                 MOTHERBOARDS

                                PART - A ( 2 marks)

1. What is meant by sockets and slots?
2. Differentiate between sockets and expansion slots
3. What is called form factor
4. What is meant by chipsets?
5. What are the two types of bridges in chipsets?
6. What is meant by BIOS?
7. Brief about the function of BIOS
8. What is the difference between BIOS &CMOS?
9. What is the major role of BIOS & CMAOS?
10. Why power management is implemented in the latest motherboard
11. What is the function of POST?

                                      PART- B

1. Explain about Intel 850GB and draw a neat block diagram if Intel 850GB Pentium 4
   motherboard?                                                                (16)
2. Write down the features of Pentium 4 motherboard and compare with Intel 850GB
                                                                                  (16)
3. Layout the AT-Style motherboard                                                (16)
4. What are the considerations to be taken to upgrade a motherboard?              (16)
5. Mention the major responsibilities of North Bridge and South Bridge using a neat
                                                                                  (16)
6. block diagram of AMD 750 Chipset                                               (16)
7. What are the major role of CMOS and its optimization tactics?                  (16)
8. Try to configure the standard CMOS setup and write down its procedure          (16)
9. Write down the procedure to configure advanced CMOS Setup                      (16)
10. What are the three services rendered by BIOS and mention about their major role
   in booting-up the system                                                        (16)
11. What are the BIOS features and what are major areas the BIOS support the CPU,
   chipsets, memory, drives, plug and ply support, power management, USB, parallel
   port and so on                                                                 (16)
12. Mention the series of steps that takes a PC from Power-on to the point where it’s
   loading an operating system (BIOS and Boot Sequences)                          (16)
13. Review the need of power supplies and power management with the concept of
   switching regulations                                                          (16)
14. How do you recognize the potential power problems and power management?(16)


                                    UNIT - III

                              STORAGE DEVICES

                              PART - A ( 2 marks)

1. What are the concepts of magnetic storage of floppy drive?
2. What is the magnetic recording principle of floppy drive?
3. Brief about data and disk organization of floppy drive
4. Draw and indicate the pin assignment for floppy drive interface
5. What is Drive Electronics of floppy drive?
6. What is meant by latency and seek?
7. What is meant by tracks, cyclinders and sectors?
   8. What are the IDE drive standards and features?
   9. What is IDE/ATA and ATAPI?
   10. Brief about CD Media
   11. What is meant by interleave?

                                         PART- B

1. Explain about Data and Disk Organization of floppy drive and is interface          (16)
2. Draw a neat block diagram and explain about floppy drive recording principle       (16)
3. Describe about the drive electronics of floppy drive with suitable diagrams        (16)
4. Draw the block diagram of floppy drive and explain its operations                  (16)
5. Explain the concept of Tracks, Cylinders and Sectors and with a data organization on
   a hard drive and typical layout of hard drive sector                              (16)
6. Comparison between binary megabytes and decimal megabytes.                        (16)
7. Explain IDE/ATA and AT API.                                                       (16)
8. With suitable diagrams, explain in detail about the concept of CD-ROM drive.      (16)
9. List out the CD Standards and characteristics.                                     (16)
10. With a neat diagram, explain the mechanism of CD-ROM with its construction.       (16)
11. Explain the main features and advantages of CD-ROM Electronics.                  (16)
12. Compare the technology of floppy drive electronics with CD-ROM Electronics.      (16)
13. List out the importance of software and drivers for CD-ROM to be installed in the PC. (16)
14. Write down the DVD Specification, Standards, Media, and Decoder of the DVD.       (16)


                                        UNIT - IV

                                   I/O PERIPHERALS

                                 PART - A ( 2 marks)

1. What do you understand from parallel port and its signal?
2. What are the IEEE 1284 modes?
3. Draw the block diagram of MIDI signals through PC.
4. What is asynchronous communications
5. What are the serial port signals and mention its importance
                                         PART - B

1. Explain the construction of modems and its operation.                      (16)
2. Explain the serial port signals and its importance.                        (16)
3. Write short notes on
       a. Parallel port signals and timing diagram.                           (4)
       b. Sound boards                                                         (4)
       c. Graphics accelerator card                                            (4)
       d. Direct X                                                            (4)
4. Explain the construction of mouse and its function of its track ball       (16)
5. Write short notes
          a. Serial port signals                                             (4)
          b. Video adapters                                                   (4)
          c. Keyboards                                                        (4)
          d. Audio benchmarks                                                (4)
                                         UNIT - V

                                   BUS ARCHITECTURE

                                   PART - A ( 2 marks)

1. What is open architecture?
2. What are the major difference between AGP and PCI?
3. What is the first open system bus and its 8 bit XT bus
4. Mention ant eight current features of PCI bus
5. List out PnP devices types and identification



                                         PART - B

   1. Provide a thorough study of SCSI host adapter with neat typical diagram of SCSI. (16)
   2. Explain 3D Graphics accelerator issues.                                        (16)
   3. Explain the layout and operation of the PCI bus.                               (16)
4. Explain AGP, its similarities with PCI, AGP layout & interface and about AGP
   Signals.                                                                 (16)
5. List out PnP devices types and identification also explain about PnP BIOS, PnP
   OS and mention essential elements(overview) of PnP.                       (16)




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Description: This question bank is prepared with a collection of various college's question sets. Thanks to all Authors.