FFT of a Superposition signal

Question

Ram Prasadh Narayanan 2022-8-11

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1777980-fft-of-a-superposition-signal

编辑： Benjamin Thompson 2022-8-11

Plot-try-matlab-1.txt

Hi,

I have a superposition signal waveform, which I am importing as a txt file, attaching the file. I would like to get the frequency components of the signal. This should be an easy code with just calling the fft function. But I am not able to see the frequency points. May be I am missing something. Could someone please help?

clc;close all
x1 = importdata('Plot-try-matlab-1.txt');
time = x1(:,1);
N = length(x1);
n = 2^nextpow2(N);
Y = fft(x1,n);
plot(Y);

Thanks for the help.

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Answer 1

Benjamin Thompson 2022-8-11

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链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1777980-fft-of-a-superposition-signal#answer_1025125

编辑：Benjamin Thompson 2022-8-11

Try this, and see this article on usage of the FFT to understand how to interpret the results and assign results to frequencies. Your time data does not make sense so I just plot results on a range of 1:n for frequency.

clc;close all

x1 = importdata('Plot-try-matlab-1.txt');

time = x1(:,1);

N = length(x1);

n = 2^nextpow2(N);

Y = fft(x1(:,2),n);

plot(1:n, abs(Y));

https://www.mathworks.com/help/matlab/math/fourier-transforms.html