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Homework Help: Signal processing help

  1. Nov 1, 2012 #1
    1. The problem statement, all variables and given/known data

    2. Relevant equations

    3. The attempt at a solution

    Having some problems with this question, using a third + first order nonlinear device to make a multiplier. I'm fine with using a second order, but this one is stumping me. So, I take x(t) = m(t) + cos(wt) and plug it into x(t) + (x(t))^3 , and I get (expanding cos(wt)2 and cos(wt)3 terms:

    5/2* m + cos(wt) + m^3 + 3* m^2* cos(wt) +3/2m cos(2wt) + 3/4* cos(wt) + 1/4* cos(3wt).

    Problem: None of the terms contain m(t)cos(wt)! Then what am I supposed to filter out?
  2. jcsd
  3. Nov 1, 2012 #2


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    Staff: Mentor

    I might be wrong here, but .... looking for clues, I notice they speak of fo and fc ....

    I wonder can fc = 2·fo?
  4. Nov 2, 2012 #3
    Thanks, after emailing the TA he confirmed that indeed fo is arbitrary here, and so fo = 2fc is the way to start answering this.
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