CWT filter bank time supports
Create a continuous wavelet transform filter bank. Set the sampling frequency to 1000 Hz and the frequency limits to range from 100 Hz to 200 Hz. Obtain the time supports of the wavelets in the filter bank.
fb = cwtfilterbank('SamplingFrequency',1000,'FrequencyLimits',[100 200]); spsi = waveletsupport(fb)
spsi=11×5 table CF IsAnalytic TimeSupport Begin End ______ __________ ___________ ______ _____ 200 "Analytic" 0.032 -0.016 0.016 186.61 "Analytic" 0.034 -0.017 0.017 174.11 "Analytic" 0.038 -0.019 0.019 162.45 "Analytic" 0.04 -0.02 0.02 151.57 "Analytic" 0.042 -0.021 0.021 141.42 "Analytic" 0.046 -0.023 0.023 131.95 "Analytic" 0.048 -0.024 0.024 123.11 "Analytic" 0.052 -0.026 0.026 114.87 "Analytic" 0.056 -0.028 0.028 107.18 "Analytic" 0.06 -0.03 0.03 100 "Analytic" 0.064 -0.032 0.032
Obtain the time domain wavelets from the filter bank and plot their magnitudes. Use the table to set the minimum and maximum limits of the x-axis to the smallest
Begin value and largest
End value, respectively.
[psi,t] = wavelets(fb); plot(t,abs(psi)) grid on xlim([spsi.Begin(end) spsi.End(end)]) xlabel('Time (sec)') ylabel('Magnitude') title('Time Domain Wavelets')
fb— Continuous wavelet transform filter bank
Continuous wavelet transform (CWT) filter bank, specified as a
thresh— Time support threshold
10e–4(default) | positive real number
Time support threshold for the wavelet, specified as a positive real
number between 0 and 0.05. The time support of the wavelet is defined as the
first instant the integrated energy of the wavelet exceeds
thresh and the last instant the integrated energy
is less than 1−
spsi— Wavelet time supports
Wavelet time supports, returned as an
MATLAB table, where Ns is the number of wavelet
bandpass frequencies (equal to the number of scales). The table has five
CF— Wavelet center frequency
Wavelet center frequency, returned as a positive real number.
IsAnalytic— Wavelet designation
Wavelet designation, returned as a string. Wavelets that do
not decay to 5% of their peak value at the Nyquist frequency are
not considered analytic. The time support information for those
wavelets are returned as
TimeSupport— Wavelet time support
Wavelet time support, returned in samples, seconds, or
MATLAB durations. The units of
TimeSupport depend on whether you
SamplingPeriod. If you specify a
SamplingFrequency, the units are seconds.
If you specify a
SamplingPeriod, the units
are the same as the
SamplingPeriod. If no
SamplingPeriod is specified, the units
Begin— Beginning of wavelet time support
Beginning of wavelet time support, returned as an integer.
Begin is defined as the first instant
the wavelet integrated energy exceeds the default threshold, 10−4.
Begin has the same units
End— End of wavelet time support
End of wavelet time support, returned as an integer.
End is defined as the last instant the
wavelet integrated energy is less than 1 − 10−4.
End has the same units