2
$\begingroup$

I'm new to DSP and trying to do some example problems for a class and am confused by this one.

Given a data set, and knowing it contains a signal that is a single sinusoid with random content noise, how can I calculate the signal to noise ratio? I also have the sampling rate.

I have been able to plot the autocorrelation, and can see the characteristic peak at 0 to indicate the noise. I'm just unsure if I can get the power of the signal and noise from this autocorrelation, or the power spectra density (taking the fft of the autocorrelation). Do I need to find the amplitude, frequency, and phase of the sinusoidal signal and subtract it from the original to do this? If so, how do I find those?

Any help is appreciated, I am new to DSP and learning to thanks!

Improve this question
$\endgroup$
1
$\begingroup$

One method is to pass the noisy sinewave through a notch filter tuned to the sine wave frequency. The output of the notch filter is N and the input is S + N. S/N = (S + N)/N - 1. This is the way some analog meters work.

Improve this answer
$\endgroup$
2
  • $\begingroup$ this will also include distortion, though $\endgroup$ – endolith Jun 20 '14 at 20:02
  • 1
    $\begingroup$ Yes, this method computes SINAD = signal to noise and distortion. $\endgroup$ – John Jun 21 '14 at 2:21

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.