CWT filter bank time supports
spsi = waveletsupport(fb)
spsi = waveletsupport(fb,thresh)
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 x-limits of the plot equal to the wavelet with largest time support.
[psi,t] = wavelets(fb); plot(t,abs(psi)) xlim([spsi.Begin(end) spsi.End(end)]) title('Time Domain Wavelets')
fb— Continuous wavelet transform filter bank
Continuous wavelet transform (CWT) filter bank, specified as a
thresh— Time-support threshold
1e–4(default) | positive real number
Time-support threshold for the wavelet, specified as a positive real
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
spsi— Wavelet time supports
Wavelet time supports, returned as a
MATLAB table, where
Ns is the number of wavelet
bandpass frequencies (equal to the number of scales). The table has the
following five variables:
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 NaNs.
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 in
seconds. If you specify a
units are the same as the
SamplingPeriod is specified, the units
are in samples.
Begin— Beginning of the wavelet time support
Beginning of the wavelet time support, returned as an integer.
Begin is defined as the first instant
the wavelet integrated energy exceeds the default threshold,
Begin has the
same units as
End— End of the wavelet time support
End of the wavelet time support, returned as an integer.
End is defined as the last instant the
wavelet integrated energy is less than
End has the same