Sound transmission

Discussion in 'The Projects Forum' started by ezgihiz, Aug 11, 2008.

  1. ezgihiz

    Thread Starter New Member

    Aug 11, 2008
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    0
    Hi;
    I'm trying to make a design with CN4046. Basically I should transmit sound from microphone to VCO then to Amplifier then to PLL and then demodulate it and take the output via speaker.
    As a start, I started desşgnşng VCO and PLL parts. as I should transmit speech, input frequency range is from 300Hz to 3,4kHz. I am having problems to determine resistance and capacitor values
    somebody help mee:confused:
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
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    If your microphone is the device that responds to the speech input, then what is the purpose of the VCO and PLL?
     
  3. ezgihiz

    Thread Starter New Member

    Aug 11, 2008
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    0
    Thank you for your response.
    The speech input is taken as an input and converted to a signal with the help of microphone. Speech signal is between 30Hz to 3,4kHz. However while transferring, you cannot transfer at small frequencies. In order to prevent distortion, you must modulate the signal with VCO and then demodulate with PLL. CN4046 datasheet doesn't contain all the values of input resistance and voltages by the way.
     
  4. Audioguru

    New Member

    Dec 20, 2007
    9,411
    896
    I think you are frequency-modulating a high VCO frequency then FM-demodulating it with a PLL.
    Just select RC parts that make a high VCO unmodulated frequency.
     
  5. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
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    Which values are you unable to find? My 1978 National Semiconductor CMOS manual lists the comparator input as 1 meg for all values of Vdd, and the signal input as 3 meg @ Vdd = 5 V, 700 K @ Vdd = 10 volts, and 300K @ Vdd = 15 volts. The VCO input is 1 meg at all values of Vdd.
     
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