waveletsupport
CWT filter bank time supports
Description
Examples
Wavelet 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')
Input Arguments
fb
— Continuous wavelet transform filter bank
cwtfilterbank
object
Continuous wavelet transform (CWT) filter bank, specified as a cwtfilterbank
object.
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−thresh
.
Data Types: double
Output Arguments
spsi
— Wavelet time supports
table
Wavelet time supports, returned as an
Ns-by-5
MATLAB table, where Ns is the number of wavelet
bandpass frequencies (equal to the number of scales). The table has five
variables:
CF
— Wavelet center frequency
positive real number
Wavelet center frequency, returned as a positive real number.
Data Types: double
IsAnalytic
— Wavelet designation
"Analytic"
| "Nonanalytic"
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 NaN
s.
Data Types: string
TimeSupport
— Wavelet time support
positive integer | NaN
Wavelet time support, returned in samples, seconds, or
MATLAB durations. The units of
TimeSupport
depend on whether you
specify SamplingFrequency
or
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
SamplingFrequency
or
SamplingPeriod
is specified, the units
are samples.
Data Types: double
Begin
— Beginning of wavelet time support
integer
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
as TimeSupport
.
Data Types: double
End
— End of wavelet time support
integer
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
as TimeSupport
.
Data Types: double
Data Types: table
Version History
Introduced in R2018a
See Also
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