MATLAB: What is the sampling frequency in wavelet method

dampingfrequenciessamplingwaveletWavelet Toolbox

Hello. I have a 1-D signal with 300 samples during 30 secs. I've extracted the frequencies which are involve in the signal already in order to compare with wavelet method.I used following codes to determine the frequencies of the signal.I guess my problem is with determining the "Fs" value. I've selected 300,100,10,… but the output was nonsense, cause the frequencies suppose to be in range of 0.1Hz,0.05Hz. but with selected "Fs" values the frequencies are about 30,10,0.7 which are not the expected frequencies.Also I would like to ask How can I estimate the damping of each frequency modes. Thanks for a fast reply
    %%------system data-------
    Fs=100; % what should it be? my time interval is 0.1 but it doesn't work too
    t=0:299;
    x=data; % its my signal value
    %%------------------------
    wname = 'morl';
    scales = 1:1:128;
    coefs = cwt(x,scales,wname);
    freq = scal2frq(scales,wname,1/Fs);
    surf(t,freq,abs(coefs)); shading('interp');
    xlabel('Time'); ylabel('Frequency');
    figure;
    wscalogram('image',coefs,'scales',freq,'ydata',x);
    hold on
    figure;
    plot(freq,coefs)

Best Answer

hi,
you have N=300 points for duration t=30 secs , then the samle rate is f=N/t=10Hz
or you can perform this way :
 T=linspace(0,30,300);
 Fs=ceil(inv(T(2)-T(1)));
The Nyquist condition is respected because you mentioned that the expected frequencies are 0<f<0.1 Hz .
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