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sine wave plot
Latest activity Commented on by Nauman Hafeez
on 28 Dec 2018
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Hi,
I am having some trouble plotting a sine wave and i'm not sure where i am going wrong.
i have
t = [0:0.1:2*pi]
a = sin(t);
plot(t,a)
this works by itself, but i want to be able to change the frequency. When i run the same code but make the change
a = sin(2*pi*60*t)
the code returns something bad. What am i doing wrong? How can i generate a sin wave with different frequencies?
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Answer by Rick Rosson
on 24 Apr 2012
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Accepted Answer
Please try:
%%Time specifications:
Fs = 8000; % samples per second
dt = 1/Fs; % seconds per sample
StopTime = 0.25; % seconds
t = (0:dt:StopTime-dt)'; % seconds
%%Sine wave:
Fc = 60; % hertz
x = cos(2*pi*Fc*t);
% Plot the signal versus time:
figure;
plot(t,x);
xlabel('time (in seconds)');
title('Signal versus Time');
zoom xon;
HTH.
Rick
2 Comments
Thanks for your reply & detailed answer.
How to calculate Fs for a particular frequency signal?
I am generating a stimulating signal using matlab for my impedance meter and it gives me different results on different Fs.
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Dear Mr. Rick, Is it possible to create knit structure in Matlab as follows:
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Answer by omphile hahilton
on 3 Mar 2015
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I would like to generate the product of 2 sine waves at frequencies 697Hz and 1209Hz and sample them and then generate the spectrum of the signal. then play the sine wave through my soundcard speakers help me..........thanks in advanced
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aaa,
What goes wrong: by multiplying time vector t by 2*pi*60 your discrete step size becomes 0.1*2*pi*60=37.6991. But you need at least two samples per cycle (2*pi) to depict your sine wave. Otherwise you'll get an alias frequency, and in you special case the alias frequency is infinity as you produce a whole multiple of 2*pi as step size, thus your plot never gets its arse off (roundabout) zero.
Using Rick's code you'll be granted enough samples per period.
Best regs
Robert
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2 Comments
Ahmed Grera (view profile)
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Govinda Nahak (view profile)
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https://se.mathworks.com/matlabcentral/answers/36428-sine-wave-plot#comment_489408
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