Aim Digital TV by waterwolltoremilion


       Hussein Nazha   SIKDER RAHMAN

             Team Work
            Siva           Nazir

   Supervised By: Dr. Anil Fernando
The aim of this project to give its readers a
view of the emerging TV technology
“HDTV” and how to implement it in an
Already existing “Home Network”
   To realize the merits of moving to a
    digitalized world
   To understand the features of HDTV
    and how it is different from Standard
   To understand the features of home
    networking and how it works
   To demonstrate how to introduce
    HDTV in home network
Moving To a Digitalized
If you have looked at television sets at any of the big
electronics retailers lately, you know that digital TV, or
DTV, is a BIG deal right now in the United Kingdom.

Most stores have whole areas devoted to digital TV sets.
You will also hear a lot about four other topics:

   1.   HDTV and HDTV broadcasts
   2.   Digital satellite services
   3.   Digital cable
   4.   DVDs and DVD players
Common Analog
 Slow-Scan Television
 Narrow Bandwidth Television
Common Digital Televisions
 Low Definition Television (LDTV)
 Standard Definition Television (SDTV)
 Enhanced Definition Television (EDTV)
 High Definition Television (HDTV)
What is Feb. 17th, 2009 DTV
  Deadline Date?
     Congress passed a law on February 1, 2006, setting a final
      deadline for the DTV transition of February 17, 2009.

     Most television stations will continue broadcasting both analog
      and digital programming until February 17, 2009, when all analog
      broadcasting will stop.

     Analog TVs receiving over-the-air programming will still work
      after that date, but owners of these TVs will need to buy
      converter boxes to change digital broadcasts into analog format.

     Converter boxes will be available from consumer electronic
      products retailers at that time. Cable and satellite subscribers
      with analog TVs should contact their service providers about
      obtaining converter boxes for the DTV transition [2].
What’s wrong with standard
 Signal degradation
 Bandwidth limitation
 Low resolution
 Noise interference
 Lifeless sound system
 Limited screen view
Solution HDTV!
   HDTV stands for High Definition Television

   It is a digital format [03] that provides an
    extremely high-resolution picture (2.1 million
    pixels), accompanied by digitally enhanced
    sound (Dolby Digital surround sound) all
    presented in widescreen (16:9 aspect ratio)

   HDTV refers to the TV itself and the broadcast
    method (over a digital network), and the way a
    particular show or movie is produced [04] [05]
Improving television with larger screens and
better resolution requires a huge increase in
transmission bit rates.

The bit rates are limited by the available
broadcast spectrum or network connection.

So what is the solution?
Compression.                                 [6]
What is compression?
   Digital video data is encoded as a series of code words that
    causes the average length of the code words to be much
    smaller than would be the case.

   Provides extra algorithmic tools for efficiently coding
    video, supports a wide range of bit rates and provides for
    multi channel surround sound coding.

   Two key techniques employed in an MPEG codec.
    - Motion-compensated inter-frame prediction.
    - Intra-frame Discrete Cosine Transform (DCT) coding.
Compression is achieved using
the well known techniques

   Prediction.
    •   motion estimation in the encoder
    •   motion compensation in the decoder
   Discrete Cosine Transform (DCT).
   Quantization of DCT coefficients.
   Huffman encoding scheme.

    The whole process allows for great savings in terms
    of bit-rate ratio (>10:1)
MPEG Coder / Decoder

   The goal is to remove the redundancy to gain better
    compression ratios.
   Exploits temporal redundancy by predicting the frame to be
    coded from a previous 'reference' frame.
   The prediction can not be based on a source picture.
        Prediction has to be repeatable in the decoder
How the prediction is done?
 Coder contains a local decoder which reconstructs pictures
  exactly as they would be in the decoder, from which
  predictions can be formed.
Prediction Continues ….
   Prediction is done by storing pictures until the desired
    reference picture is available before encoding the "current"

   The encoder can decide on a macro block basis to use
    forward prediction from a previous picture, backward
    prediction from a following picture.

   Interpolated prediction to minimize prediction error.

   The decoder must have two frame stores.
Prediction Continues ….
    Discrete Cosine Transform
   It transforms a signal or image from the spatial domain to the
    frequency domain.

   An image is decomposed and then created by using set of basic

   Helps to separate the image into parts of differing importance
    (with respect to the image's visual quality).
Discrete Cosine Transform


• 64 pixel tile is converted into 64 frequency values.
• Starting from the DC value the other 63 frequency values are
scanned out in a zigzag pattern.
• The encoder applies variable uniform quantization threshold to
DCT coefficients to reduce the number of bits required to
   High-frequency coefficients being more coarsely quantised
    than the low-frequency coefficients.
   All samples smaller than the threshold are cleared out to
   Higher the threshold the higher the compression, but also
    the lower the image quality.
   Erasing smaller frequency values removes detail resolution
    in the images and also introduces image artifacts.
    Not acceptable for scientific or medical imaging
   Quantisation noise introduced by the coder is not reversible
    in the decoder, making the coding and decoding process
Huffman code
   Basically, it compresses the data by assigning codes with
    fewer bits to the most often encountered output patterns.

   An entropy code achieves the shortest average possible
    code word length for a source.

   Transmissions are highly sensitive to error propagation.

   Even a single bit error in the transmission can cause the
    image to break up into random noise until an error recovery
    code is detected. This produces very disturbing visual
    effects in noisy transmissions.
     Issues in HDTV
1.    Bandwidth.
      - Conventional NTSC image bandwidth 3.35 MHz.
      - HDTV image needs bandwidth of 18 MHz.

      What limits this?
      - Current terrestrial channel allocations are limited to 6 MHz!
      What would be the Solution?
      - Change channel allocation system from 6 MHz to 20 MHz.
      - Compress signal to fit inside the 6 MHz existing bandwidth.
      - Allocate multiple channels for the HDTV signal.
    Issues in HDTV Continues ….
2. Interlaced versus non-interlaced - Kell factor
    Actual observed resolution is lesser than the vertical resolution promised
     by a TV system.
For Progressive Scanning :
    about 70% of the maximum resolution.
For Interlaced Scanning :
    Stationary Image : about 70% of the maximum resolution.
    Non Stationary Image: about 50% of the maximum resolution.

     Due to the possibility of a picture element (pixel) falling "in-
     between" the scanning lines
Issues in HDTV Continues ….

Benefits of HDTV
   A wider aspect ratio is a better match for movies. The normal American
    TV standard, called NTSC, uses a 4:3 aspect ratio, while HDTV
    provides for 16:9

   The higher resolution of HDTV gives a more detailed and realistic

   With digital TV, you get CD quality sound, too - Dolby AC-3, also known
    as Dolby Digital 5.1.
Benefits of HDTV Continue…
   Being digital, HDTV will eliminate noise and ghosting

   Accommodate more information within the same bandwidth used by
    standard TV

   Maintain the same quality as original

   Multicasting
Comparison Table
Home Networking
   Way of connecting the different
    electronic devices in a household by
    way of a local area network (LAN)

   Application of home networking
     –   Resource sharing
     –   Communication
     –   Home control
     –   Home scheduling
     –   Entertainment
Technology Used in Home
   Wired [11]
     –   Ethernet
     –   HomePNA or HPNA
     –   Powerline

   Wireless [12]
     –   Wireless Ethernet
     –   HomeRF
     –   Bluetooth
Advantages and Disadvantages
of Wired Technology
   Advantages:
     –   Faster data transmission rate up to 100 Mbps
     –   It is reliable and based on industry standard
     –   HomePNA uses existing phone line so no extra wiring
     –   Powerline use the home powerline also no need for
         extra wiring
     –   Easy to install

   Disadvantages:
     –   Ethernet involves new wiring so it is costly
     –   Require hub, router, and server for intelligent
     –   All the device must be connected to the wire to form the
     –   Not flexible
Advantages and Disadvantages
of Wireless Technology
   Advantages:
     –   As this is wireless so no wiring is required
     –   It provides the mobility
     –   It is flexible
     –   Easy to install
     –   Sometimes less expensive as no wiring is required

   Disadvantages:
     –   Can have structural setbacks
     –   It does not support long distange communication
         because of range problem
     –   Bandwidth limitations
     –   Can be very expensive
Elements Needed for HDTV in
Home Network
 Specialised  HDTV antenna
 HDTV compatible set-top box
 Video distribution System
 Multimedia over coax      [13]
Issues to be Considered to
Introduce HDTV in Home
   Bandwidth
   Connectivity
   Structure
   Security
 HDTV is here to change our watching
 It’s true that the costs for such TVs are high
  but eventually will drop as features continue to
 HDTV is a far superior media for delivering
  our television programs
 With HDTV broadcasts already underway, it is
  only a matter of a few years before HDTV
  technology is perfected and available in large

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