Asymmetric

clear; close all
Fs=1; % Sampling frequency [Hz] dt=1/Fs; % Time sample interval [s] n=1024; % signal length
T=dt*(n-1); % Signal duration [s] t=(0:dt:T)’; % Time vector
A01=1-linspace(0,0.1,n); % Signal amplitude
A02=0.5+linspace(0,0.5,n); % Signal amplitude
f0=0.01+linspace(0,0.05,n); % Signal frequency [Hz]

x1=A01.*cos(2*pi*cumtrapz(f0.*dt)); % Signal

x2=A02.*cos(2*pi*cumtrapz(f0.*dt));
x=x1;
x(x1>=0)=x2(x1>=0);

figure(1)
plot(x,’.-‘);
grid on; axis tight
ylabel(‘Amplitude’);
xlabel(‘Points’);
title(‘Harmonic signal’)

figure(2)
strips(x,256)

ylabel(‘Amplitude’);
xlabel(‘Points’)
title(‘Signal in strips’)

figure(3)
[Pxx,F] = pwelch(x,[],[],1024,Fs); % Create a Welch spectrum
semilogy(F,Pxx); axis tight
ylabel(‘Power spectral density’);
xlabel(‘Frequency, Hz’);
title(‘Spectrum’)