# How can i plot three periods of a signal

77 views (last 30 days)
Deniz Bozdogan on 12 Jun 2021
Answered: Scott MacKenzie on 13 Jun 2021
Hello, i have the following signal and i want to plot three periods of it
t=[0:0.0002:20];
xc1=cos(2*pi*493.88*t);
How can i do it? Thank you for your help

Image Analyst on 12 Jun 2021
Try it this way:
% t=[0:0.0002:20];
% xc1=cos(2*pi*493.88*t);
% argument in cos = 2*pi*t/period. So
period = 1/493.88
threePeriods = 3 * period
% Make 1000 points over that 3 period.
t = linspace(0, threePeriods, 1000);
% Make xc1 with that t:
xc1 = cos(2 * pi * t / period);
% Plot it
plot(t, xc1, 'b-', 'LineWidth', 2);
xlabel('t', 'FontSize', 15);
ylabel('xcl', 'FontSize', 15);
grid on;
caption = sprintf('Three Periods of cos(2 * pi * t / period), where period = %f', period);
title(caption, 'FontSize', 15);
Deniz Bozdogan on 12 Jun 2021
Thank you so much

Scott MacKenzie on 13 Jun 2021
If you want to plot three periods of a signal and do it by extracting the data from your existing code, then
t=[0:0.0002:20];
xc1=cos(2*pi*493.88*t);
idx3 = find(t>=3/493.88,1);
plot(xc1(1:idx3));

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