How to convert fft plot into PSD(Normalized) vs Freqeuncy (Hz)

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I am trying to convert my fft signal into PSD(Normalized) vs Freqeuncy (Hz) but can't get it right. I want to get some thing like shown in the figure. I found these figures in the literature. How to plot this in matlab? PSD from 0-1 and frequency in log scale.
If some one can explain with a simple example, it will be highly appreciated

Answers (2)

Vidya Viswanathan
Vidya Viswanathan on 1 Apr 2016
I understand that you are trying to compute the power spectral density of a signal from the output of the FFT function. This can be done by squaring the absolute value of FFT output and scaling it by a factor equal to (1/length(data))*(1/Fs) where Fs is the sampling frequency. This result is then converted to decibels. Refer to the following documentation link that describes how power spectral density can be computed from FFT:
I hope this answers your question.

remi inshar
remi inshar on 3 Aug 2018
hai all... i am trying to plot psd of action potential in neurons.. i am not able to select the sampling frequency wisely and reproduce plots in a famous journal.. can someone help me....?

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