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Homework Help: Signal to Noise Ratio: Questions for my multimedia and signals class

  1. May 12, 2010 #1
    Question one
    1. The problem statement, all variables and given/known data
    x[n] = 5sin(0.22*pi)
    The root mean square (RMS) value eof a sin wave is known to be A/root(2) where A is the amplitude. If the noise in a system is known to have an RMS value of 0.5, what si the signal to noise ration (in dB) of the x[n] in this syetem.

    2. Relevant equations
    RMS = A/root(2)
    SNR = (Asignal/Anoise)^2
    SNRdB = 10log10(SNR)

    3. The attempt at a solution
    Well, i figured that "A" for the RMS given (0.5) is root(2)/2

    However, i do not know that which A is Asignal and which is Anoise (root(2)/2 or 5*sin(.22*pi) or just 5).
     
  2. jcsd
  3. May 12, 2010 #2

    Mark44

    Staff: Mentor

    Shouldn't the formula above have n on the right side? Otherwise, all your values of x[n] are exactly the same.
     
  4. May 12, 2010 #3
    Thats what I keep thinking, but i that isnt what the problem has in the notation.
     
  5. May 12, 2010 #4

    Mark44

    Staff: Mentor

    Then I'd be willing to bet that it's a typo. Otherwise you don't have a sine wave. In that case x[n] is equal to about 3.1871 for all n. IOW, it's constant.
     
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