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Self demodulating amplifier

Discussion in 'Electronic Design' started by gagir, Sep 20, 2003.

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  1. gagir

    gagir Guest

    Trying to filter a <l00Hz modulated signal, I have across serious filter
    design.

    I looked to PLL's and a lot is telecom.

    Any good reading on instrumentation demodulation would be appreciated.

    Eric Girard
     
  2. Bob

    Bob Guest

    A little more information on what you are trying to do would be helpful:

    What kind of modulation is it (e.g. AM, FM, PM)?
    What are the carrier and modulation frequencies?
    What other signals are present that you want filtered out?
    What do need for a result (a measure of the amplitude of the modulating
    signal or the signal itself)?

    A lockin might be what you mean by a demodulation instrument. Try:

    http://www.thinksrs.com/html/applicationnotes.html

    http://www.thinksrs.com/html/technote.html

    http://www.thinksrs.com/html/sr830.html

    Bob
     
  3. gagir

    gagir Guest

    For process monitoring I need to filter out photodiode noise of the same
    amplitude as the modulated signal.

    Since the process is modulated at 0 to 100Hz I want to see if a resonant
    filter would demodulate to have phase and amplitude info.

    Would switch capacitor filters cause phase jitter?

    Or would a lowpass with a high Q would be better?

    Readings on that.

    Thank you for your links.

    Eric Girard
     
  4. gagir

    gagir Guest

    Yeah you are right, just try it...
    I will be going with a LTC swiched filter an will see.

    gagir
     
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