FM Demodulator with Tv Tuner

Discussion in 'Radio and Communications' started by Masood786, Dec 16, 2010.

  1. Masood786

    Masood786 Thread Starter New Member

    Joined:
    Dec 16, 2010
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    Hi All
    I have a Tv tuner that outputs 38.9 mhz If signal. I want to connect
    FM demodulator in front of it to receive Fm broadcast signals (88-108Mhz) as well as other transmissions. I have seen over the web at
    http://hem.passagen.se/communication/pic/uv916tr.gif
    fm demodulator but the demodulator IC MC13136 requires many external components as it converts the signal into 10.7mhz If. so as other ICs like FM radio receivers TDA7000 and LA1800.
    Can any one tell me how to demodulate 38.9Mhz signal without conversion.
    Is there any IC that can extract audio without converting it to 10.7Mhz.
  2. beenthere

    beenthere AAC Fanatic!

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    Both the 38.9 MHz and 10.7 MHz signals are IF frequencies. You do the demodulation after the IF stage.

    I would suggest that any superheterodyne receiver is going to be as colplex as another, so trying to use the 38.9 MHz IF will require as much circuitry as the standard 10.7 MHz IF for FM broadcasts.

    You may be able to find direct conversion IC's. You can look at this link - http://en.wikipedia.org/wiki/Radio_receiver_design
  3. Masood786

    Masood786 Thread Starter New Member

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    Dec 16, 2010
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    Thanks for the reply,
    Is there any IC i can use 38.9Mhz IF signal as Rf input, TDA7000 has RF input ranging from 70 to 120 Mhz but mine is 38.9Mhz.
    Any ideas ? Is there any other IC that does't require Quad Coil for demodulation,discriminator/ PLL demodulator, that operates in the range that covers 38.9Mhz. I have heard of NE565 but it works in Khz.
    Please Reply soon.
  4. bertus

    bertus Administrator Staff Member

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    Apr 5, 2008
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    Amsterdam,Holland (GMT + 1)
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