Frequency of Noise Signal at Receiver

Hallo everyone,

Let's say i've the magnitude of a signal and this signal has interferenced by some noise. Does anyone know, how we can calculate the phase and frequency of noise signal in receiver using Matlab?

Thanks before.

[Star Strider]

Context: How can i determine phase in FFT?

Answer 1

[Star Strider]

What do you mean by ‘noise’?

Random (broadband or band-limited) noise has no specific phase (it is random in all respects). Band-limited noise can (probably) be filtered out of your signal, but it may also filter out the same frequencies in your original signal. A Fourier transform of your signal with band-limited, non-random noise will reveal its phase.

Answer 2

[Big dream]

I've a signal with for example 100khz. Because some acoustic noise from control valve,it will interference my signal information. In this case, i would like to know the freq and phase of this acoustic noise. Did you mean, i only can reveal its phase,not the frequency?

[Star Strider]

That depends on the nature of the noise. If it is essentially broadband and random, the phase and frequency are also random, so isolating them is not possible.

If your noise is band-limited, you can find the frequency band of the noise with a Fourier transform and (probably) eliminate the noise with an appropriately-designed filter, but if it is again random, the phase of the noise will be random.

If your signal is the data you posted earlier (in your previous Question), we have already done everything we can with respect to isolating the signal and eliminating the noise.

Answer 3

[Big dream]

I see. Yes,it's relevant with my previous question. Thanks very much.

I've heard something about wavelet transformation. Do you have experienced with this trnasformation? Does wavelet transform better than fourier transform?

[Star Strider]

As always, my pleasure.

[Star Strider]

I have some experience with wavelets from graduate school, but none recently. The Wavelet Toolbox has a GUI denoising demonstration if I remember correctly. (I have the Wavelet Toolbox but haven’t used it recently.) See the documentation for the mswden and related functions. Search the documentation for ‘denoising’ to find all the applicable functions.

[Big dream]

ok,thanks.