how to calculate frequency from the wavelet toolbox?

Question

Baidehi Nanda 2012-4-7

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https://ww2.mathworks.cn/matlabcentral/answers/34786-how-to-calculate-frequency-from-the-wavelet-toolbox

I am uploading a signal and performing wavelet analysis using continous wavelet 1-D,I get the coefficient waveform,how do I now calculate the frequency of the given waveforms?

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Answer 1

Wayne King 2012-4-7

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在 MATLAB Online 中打开

You can use scal2frq to return the pseudo-frequencies corresponding to particular scales.

For example:

 t = linspace(0,5,5e3);
 x = cos(2*pi*100*t).*(t<1)+cos(2*pi*50*t).*(3<t)+0.3*randn(size(t));
 % determine scales
 fc = centfrq('cmor1-1');
 % a = fc/(freq*dt)
 freqrange = [20 150];
 Fs = 1000;
 scalerange = fc./(freqrange*(1/Fs));
 scales = scalerange(end):0.2:scalerange(1);
 Coeffs = cwt(x,scales,'cmor1-1');
 F = scal2frq(scales,'cmor1-1',1/Fs);
 contour(t,F,abs(Coeffs)); 
 xlabel('Time'); ylabel('Frequency');

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Baidehi Nanda 2012-4-8

Is there any way to calculate frequency from the waveform that is visible on the window? Because,you see,the signal that I am referring to is a transient voltage waveform at a particular point on a power network during switching.I cant reconstruct such a signal in matrix or vector form in the command window..so.please help.

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