Normally, when talking about adding noise to simulation data, the choice are AWGN, pink noise and so on. However, in practice, the noise in the experiments changes the locations of frequency peaks as well. How can I simulate this kind of noise?

  • $\begingroup$ Sounds like you might be overdriving amplifier inputs and getting clipping which introduces intermodulation products (peaks at other frequencies). $\endgroup$ – Andy Walls Oct 31 '19 at 13:49

I'm not sure I understand your question.

But usually the noise model is additive.
Namely, due to the linearity of the DFT, at each bin you will have the summation of the signal contribution and the noise contribution at this specific frequency bin.

Now, let's say we have 2 bins.
At the first the signal is 7 at the second is 6.
The noise is 3 and 5 respectively, now the summation will shift the DFT peak though the signal isn't changed.

  • $\begingroup$ This is a good point. I know this is a silly question, but in the experiments, the measured frequencies change between several tests. In some tests, some frequencies disappear. Adding white noise to simulation data can not simulate the experimental situation. The SNR is not very low for the experiments, thus for AWGN it is unlikely to have very high peaks. $\endgroup$ – Kattern Jun 21 '15 at 10:06
  • $\begingroup$ I agree with Drazick; noise is usually additive and has a simple spectrum, so it can't do things like shift a frequency peak present in the data signal. Something else is going on in your experiment, such as fading or Doppler, or even some non-linear effect (for example, non-linear distortion can make your fundamental harmonic to lose power). $\endgroup$ – MBaz Jun 21 '15 at 15:48
  • $\begingroup$ Frequency could change due to Doppler shift as you've been told, or by frequency mismatch of reference generators if you use two or more boards. If some non-linear things happened it will be additional frequency in the spectrum but the original ones will stay the same. In the case of fading without Doppler spread frequency content won't be affected. You can describe your experiment for more understanding of your interesting phenomenon. $\endgroup$ – Serj Jun 22 '15 at 7:19
  • $\begingroup$ @Kattern, Could you please mark my answer? $\endgroup$ – Royi Mar 16 at 6:33

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.