Finding the Demodulator value

Discussion in 'The Projects Forum' started by goldfish300, Nov 29, 2009.

  1. goldfish300

    Thread Starter Member

    Mar 12, 2009

    i would like to as a question about some kind of issue about finding the value "x" that is shown the fig below , well the value of the Freq. should be 96Khz which is the value i need to reach and this is by passing some stages to reach only the value of the freq. =96Khz (thats mean removing all the previous Freq. and voltages and only keeping the last value of Freq =96Khz in order to have the analogue graph . so i'll post what stages i must pass in order to reach that point that iv tried but still can't figure out . if someone know plz help as soon as u can .

    here is the pic of the circuit that i attached in the post for those who can help me :(


    and the stages that must pass through this circuit must look like that

  2. Ron H

    AAC Fanatic!

    Apr 14, 2005
    Your post makes no sense to me.
  3. SgtWookie


    Jul 17, 2007
    Actually, it makes sense to me.

    You have 4 signals being summed:
    50Hz 220v
    10kHz, 10v
    20KHz, 5v
    X kHz, 10v
    One way to approach it would be to use three very narrow band-reject filters in series; one for 50Hz, one for 10kHz, and one for 20kHz.
    Another way would be to subtract the known frequencies in subsequent sum modules, eg: instead of summing the signal with 50Hz 220v the second time, sum it with 50Hz -220v, which should be 180º out of phase with the original 50Hz 220v.

    Oops, OK, I posted without really looking at the 2nd part of the question very hard.

    The 1st high-pass filter can get rid of most of the low-frequency stuff.

    I don't know what you mean by a high-pass filter with same frequency carrier. Are you trying to say an IF section?

    An LC tank acts as an open circuit to it's resonant frequency, and as a short to ground to frequencies other than resonant.

    I guess this is homework, but you don't know where to start, right?
    Last edited: Nov 30, 2009
  4. Ron H

    AAC Fanatic!

    Apr 14, 2005
    One of the things that confused me was the title.