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ECE5320 Assignment_1

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					              ECE5320 Mechatronics
Assignment#01: Literature Survey on Sensors and Actuators

                  Topic: Microphone


                      Prepared by:

                     Balaji Ravindran
      Dept. of Electrical and Computer Engineering
                   Utah State University

                        3/6/2008
                                          Slide-2



                                   Outline
       –    Reference list
       –    To probe further
       –    Major applications
       –    Basic working principle illustrated
       –    A typical sample configuration in application
            (application notes)
       –    Major specifications
       –    Limitations



6/10/2011           ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators
                                       Slide-3



                       Reference list
  • Hearing AIDS: Standards, Options, and Limitations
    By Michael Valente
  • Robertson, A. E.: "Microphones" Illiffe Press for BBC,
    1951-1963
  • http://arts.ucsc.edu/EMS/Music/tech_background/
    TE-20/teces_20.html
  • http://www.tonmeister.ca/main/textbook/node473
    .html
  • http://www.wikirecording.org/Condenser
6/10/2011        ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators
                                      Slide-4

               To explore further
    (survival pointers of web references etc)
  • http://www.listeninc.com/site/images/Microphone_Test_
    Setup.jpg
  • http://www.infineon.com/dgdl/smm310.pdf?folderId=db
    3a30431428a37301143a65efcb01df&fileId=db3a304314
    dca3890114f475ee1c06e8
  • http://hyperphysics.phy-
    astr.gsu.edu/Hbase/audio/mic.html#c3
  • http://en.wikipedia.org/wiki/Microphone


6/10/2011       ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators
                                      Slide-5



                Major applications
  •   Recording Studios,
  •   Telephones / Mobile / Voice Communication,
  •   Hearing Aids,
  •   Motion Pictures
  •   University / Public / Private Conferences
  •   Computers
  •   Space Applications
  •   Medical Applications
6/10/2011       ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators
                                     Slide-6



       Basic working principle illustrated
  • Thin membrane – vibrating in response to a sound
    pressure – movement converted to electrical
    signal.




6/10/2011      ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators
                                            Slide-7



                            Classification
  • Types
       –    Capacitor or electrostatic Microphones
       –    Dynamic Microphones
       –    Piezo-electric Microphones
       –    Carbon Microphones
       –    Laser Microphones
       –    Liquid Microphones
  • Type classification – classifies the diaphragm’s
    placement and position.
6/10/2011             ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators
                                         Slide-8



                         Classification
  • Capacitor or Electrostatic Microphone
       – Diaphragm – one plate of a capacitor – vibration –
         produces changes in distance between plates
       – Voltage maintained across the parallel plates varies
         with vibrations – Q = C * V
       – Power is required for establishing the capacitor plate
         voltage and for internal amplification of output




6/10/2011          ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators
                                            Slide-9



                            Classification
  • Dynamic Microphones
       – Works on Induction principle
            • Moving Coil Microphones and
            • Ribbon Microphones
            • No external power source required
       – Moving Coil – small movable induction coil – placed
         in the field of a permanent magnet – attached to the
         diaphragm



6/10/2011             ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators
                                       Slide-10



                        Classification
  • Dynamic Microphones
       – Ribbon Microphone - Ribbon – electrically connected
         to the microphone’s output – vibration within
         magnetic field – generates electrical signal.




6/10/2011         ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators
                                        Slide-11



                         Classification
  • Carbon Microphone
       – Carbon granules pressed between the plates – when
         diaphragm vibrates – adjacent granules change – this
         changes the electrical resistance of granules – this
         changes voltage and hence current flows – producing
         electrical signal




6/10/2011          ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators
                                        Slide-12



                         Classification
  • Piezo - Electric Microphone
       – Uses piezo-electric crystals attached to diaphragm,
         which produces voltage when pressure is applied.
       – Such Microphones mostly used in musical
         instruments.




6/10/2011          ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators
                                           Slide-13



     A typical sample configuration in application
  • MEMS Microphone from Infineon
       –    Based on MEMS technology
       –    Assembled directly on PCB
       –    Used in Mobile phones and medical appliances
       –    Robust Design
       –    High temperature stability
       –    Alternative to traditional capacitor microphones
       –    Surface Mountable Device


6/10/2011             ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators
                                    Slide-14


    A typical sample configuration in application




6/10/2011      ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators
                                      Slide-15


    A typical sample configuration in application
  • Figure shows a typical SMM310 microphone
    connected to a pre-amplifier circuitry.




            (Image Courtesy : Infineon Technologies)




6/10/2011        ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators
                                          Slide-16



                    Major specifications
  • Major Specifications in a microphone are
       –    Frequency response
       –    Noise
       –    Sound-Pressure Level
       –    Clipping Level
       –    Dynamic range
       –    Sensitivity



6/10/2011            ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators
                                        Slide-17



                 Major Specifications
  • Frequency Response
       – measure of any system's spectrum response at the
         output to a signal of varying frequency at its input.
       – In microphone, frequency response is a plot of the
         microphone’s sensitivity over a range of frequencies.




6/10/2011          ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators
                                        Slide-18



                 Major Specifications
  • Noise
       – Sound level that creates the same output voltage as the
         microphone does in the absence of sound.
       – Represents the lowest point of the microphone's
         dynamic range.




6/10/2011          ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators
                                       Slide-19



                Major Specifications
  • Sound Pressure Level
       – Measured in terms of maximum Total Harmonic
         Distortion that the microphone can accept.
       – Higher the value, the better the microphone.




6/10/2011         ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators
                                       Slide-20



                 Major Specifications
  • Clipping Level
       – Measure of maximum usable / output level of the
         microphone
       – Usually a measure of Total Harmonic Distortion
       – Should be avoided




6/10/2011         ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators
                                       Slide-21



                Major Specifications
  • Dynamic Range
       – Difference between noise floor and maximum SPL




6/10/2011         ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators
                                        Slide-22



                 Major Specifications
  • Sensitivity
       – is the minimum magnitude of input signal required to
         produce a specified output signal having a specified
         signal-to-noise ratio(General Definition)
       – The sensitivity of a microphone is usually expressed
         as the sound field strength.
       – indicates how well the microphone converts acoustic
         pressure to output voltage
       – the (preferred) international standard is made in mill
         volts per pascal at 1 kHz
6/10/2011          ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators
                                      Slide-23



                           Limitations
  •   Internal Noise
  •   Wind Noise
  •   Distortion at higher signal level (108 dB more)
  •   Sensitivity to frequencies outside frequency range
  •   Sensitivity to vibration
  •   Environmental stability
  •   Possible foreign material entering sound port


6/10/2011        ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators
   Slide-23



                           Limitations
  •   Internal Noise
  •   Wind Noise
  •   Distortion at higher signal level (108 dB more)
  •   Sensitivity to frequencies outside frequency range
  •   Sensitivity to vibration
  •   Environmental stability
  •   Possible foreign material entering sound port


6/6/2011         ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

				
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