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Modulator and Demodulator (conceptual question)?

  1. Oct 28, 2011 #1
    Just a quick conceptual question.

    If you have a sinusoidal signal of 3kHz with an amplitude of A, and it's going through a modulator, and then going through a demodulator, must the output of the modulator resemble exactly to the original signal?

    The reason why I am asking is because when I was doing this in my lab, the output of the modulator had the same frequency of the original signal, but 1/10 of the Amplitude.

    I thought it would have A/4 instead.

  2. jcsd
  3. Oct 28, 2011 #2
    It all depends on your system.

    A perfect modulator and demodulator would result in an output that exactly matched the original signal.

    In reality the demodulator stage may be such that you get a demodulated signal has an attenuated amplitude. Ideally this attenuation would be known and linear so that you can amplify the signal back to its original state.

    So I guess I would say I need more detail to really answer better than that. Why did you expect A/4 to begin with? What type of modulation were you performing?
  4. Oct 28, 2011 #3
    Never mind, I just calculated the gain for the modulator and demodulator.

    The reason I thought it would be A/4 is because I remembered the professor gave us an ideal circuit diagram that had a specified gain value for both the modulator and demodulator.

    Thank you for your input!
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