49 lines
1.0 KiB
Matlab
49 lines
1.0 KiB
Matlab
function power = frequencySpectrum(signal, fs)
|
|
%%%%%%%%%%%%%%%%%%
|
|
%function frequencySpectrum(signal, fs)
|
|
%
|
|
% Task: Display the power spectrum of a given signal
|
|
%
|
|
% Input:
|
|
% - signal: the input signal to process
|
|
% - fs: the sampling rate
|
|
%
|
|
% Output:
|
|
% - power: power spectrum of the signal
|
|
%
|
|
%
|
|
% Guillaume Gibert, guillaume.gibert@ecam.fr
|
|
% 25/04/2022
|
|
%%%%%%%%%%%%%%%%%%
|
|
|
|
n = length(signal); % number of samples
|
|
|
|
y = fft(signal, n);% compute DFT of input signal
|
|
power = abs(y).^2/n; % power of the DFT
|
|
|
|
[val, ind] = max(power); % find the mx value of DFT and its index
|
|
|
|
% plots
|
|
figure;
|
|
|
|
subplot(1,3,1) % time plot
|
|
t=0:1/fs:(n-1)/fs; % time range
|
|
plot(t, signal)
|
|
xticks(0:0.1*fs:n*fs);
|
|
xticklabels(0:0.1:n/fs);
|
|
xlabel('Time (s)');
|
|
ylabel('Amplitude (a.u.)');
|
|
|
|
subplot(1,3,2) % linear frequency plot
|
|
f = (0:n-1)*(fs/n); % frequency range
|
|
plot(f,power, 'b*'); hold on;
|
|
plot(f,power, 'r');
|
|
xlabel('Frequency (Hz)')
|
|
ylabel('Power (a.u.)')
|
|
|
|
subplot(1,3,3) % log frequency plot
|
|
plot(f,10*log10(power/power(ind)));
|
|
xlabel('Frequency (Hz)')
|
|
ylabel('Power (dB)')
|
|
|