i need a MATLAB code of power spectral density PSD with out built in function, i want a code that work with the same as the built in function of periodogram().
Kindly see the code below if its helps:
clear all
%% Define Parameters
% sampling frequency (Hz)
fs=100e6;
% length of time-domain signal
L=30e3;
% desired power specral density (dBm/Hz)
Pd=-100;
% number of FFT points
nfft=2^nextpow2(L);
% frequency plotting vector
f=fs/2*[-1:2/nfft:1-2/nfft];
% create
s=wgn(L,1,Pd+10*log10(fs),1,[],'dBm','complex');
%% Analysis
% analyze spectrum
N=nfft/2+1:nfft;
S=fftshift(fft(s,nfft));
S=abs(S)/sqrt(L*fs);
% time-average for spectrum
Navg=4e2;
b(1:Navg)=1/Navg;
Sa=filtfilt(b,1,S);
% convert to dBm/Hz
S=20*log10(S)+30;
Sa=20*log10(Sa)+30;
%% Plot
figure(1)
clf
plot(f(N)/1e6,S(N))
hold on
plot(f(N)/1e6,Sa(N),'r')
xlabel('Frequency (MHz)')
ylabel('Power Density (dBm/Hz)')
title(['Power Spectral Density'])
legend('Noise Spectrum','Time-Averaged Spectrum')
axis([10e-4 fs/2/1e6 -120 -60])
grid on
hold off
Source: http://www.bitweenie.com/listings/power-spectral-density-matlab/
http://www.bitweenie.com/listings/power-spectral-density-matlab/
Power Spectral Density Estimates Using FFT
Dear, check the following link, may help you:
http://www.mathworks.com/examples/signal/mw/signal-ex08634157-power-spectral-density-estimates-using-fft
Try below code:
note:Fs depends upon data
[k,col]=size(data);
fft_samps = 2^nextpow2(k);
t_fft = fft (data, fft_samps)/k;
Fs=--------;
fprime = Fs/2*linspace(0,1,fft_samps/2);
plot(fprime,2*abs(t_fft(1:fft_samps/2)));
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