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construct gaussian white noise with particular SNR

Started by biswasengupta November 17, 2008
hi there,

My issue is as follows: consider I have a low-pass filtered version of
a white noise signal (fc00 Hz, LPF) as my signal. I would like to add
different Gaussian white noise having different SNR referred to the LPF
signal. I do the following.

1. I get the power of the signal using = mean(original_signal.^2) ->
{say P_s}
2. standard deviation of the required noise = sqrt(P_s / SNR) ->
{noi_std}
3. construct noise using noise_trace = noi_std.*randn(1000,1)

Now the question is, in step 1 when I am computing the power of the
signal do I use the orginal signal or the original signal with the mean
removed ?

Thanks, BSG