Harmonics

Fs=1; % Sampling frequency [Hz]
dt=1/Fs; % Time sample interval [s] n=512; % Signal length
T=dt*(n-1); % Signal duration [s] t=(0:dt:T)’; % Time vector
A0=1.*ones(n,1); % Signal amplitude
f0=0.02.*ones(n,1); % Signal frequency [Hz] x=A0.*cos(2*pi*cumtrapz(f0.*dt)); % Signal wave

figure(1)plot(t,x,’.-‘);
grid on; axis tight
ylabel(‘Amplitude’);
xlabel(‘Time, s’);
title(‘Harmonic signal’);

figure(2)
strips(x,128)
ylabel(‘Amplitude’);
xlabel(‘Points’)
title(‘Signal in strips’)

figure(3)
[Pxx,F] = pwelch(x,[],[],512,Fs); % Create a Welch spectrum
plot(F,Pxx);
ylabel(‘Power spectral density’);
xlabel(‘Frequency, Hz’);
title(‘Spectrum’)