amplitude of non-periodic signal

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mustafa alnasser 2015-10-2

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https://ww2.mathworks.cn/matlabcentral/answers/246482-amplitude-of-non-periodic-signal

评论： Star Strider 2015-10-3

采纳的回答： Star Strider

Dear All; if I have a non periodic signal/wave , how can i calculate the amplitude and wavelength ?

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Answer 1

Star Strider 2015-10-3

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Another possibility is in the code I used in this Answer. The peak times (the periods are the differences between them) will be in t(zx_idx) and the amplitudes will be in C(zx_idx) in that code.

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mustafa alnasser 2015-10-3

Thank you but where is the code ?

Star Strider 2015-10-3

在 MATLAB Online 中打开

It is in my Answer. I am reposting it here:

t = linspace(0, 10, 1000);                      % Time
C = 2 + sin(2*pi*t + cos(5*pi+t)*pi);           % Signal
dC = diff([0, C])/(t(2)-t(1));                  % Approximate Derivative
dCzx = dC .* circshift(dC, [0 -1]);             % Negative Values => Zero Crossings (Mostly)
zx_idx = find(dCzx <= 0);                       % Derivative Zeros Are Maxima, Minima Of ‘C’
figure(1)
plot(t, C)
hold on
plot(t(zx_idx), C(zx_idx), 'or')
hold off
grid
axis([xlim    0  5])

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Answer 2

Image Analyst 2015-10-3

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As you know, any arbitrary signal can be considered as a weighted sum of a bunch of sine waves - that's the whole concept of Fourier analysis. I suggestion you look at the fft() function or the pwelch() function.