Time and Frequency analysis
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Hello,
I have data of measured signal in time. I want to know the frequencies of the components of my signal (Large scale fading+Small scale fading+Noise). For this reason, I have represented the FFT of my signal. I would like to know the time instant where the peaks highlited in yellow happened. Does any one have an idea how to do it?
Another question, How can I extract each component of the original signal from the FFT representation?
Thank you in advance.
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Star Strider
2020-3-5
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The peaks in the fft result can occur anywhere in the signal. To do a time-frequency analysis, use the spectrogram function.
4 个评论
yusra Ch
2020-3-5
You mean like this? Do you know how to represent the frequency axis in Hertz?
Star Strider
2020-3-5
Yes. Experiment with the different parameters and name-value pair arguments to get different results.
To get the frequencies in Hz, specify the sampling frequency, fs. See: Spectrogram and Instantaneous Frequency.
yusra Ch
2020-3-5
I have specified these parameters:
Fm=1000;
Freq=0:Fm/length(potencia(L,:)):Fm/2;
spectrogram(power,[],[],Freq,Fm,'yaxis');
I know that the spectrogram explains how the signal strength is distributed in every frequency found in the signal. However, I don't know how can I extract information about the large scale fading, small scale fading and noise.
Star Strider
2020-3-5
That is likely not possible to extract from a spectrogram.
This sounds like a communications problem rather than the signal processing problem I first thought it was.
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