wavelets
DWT filter bank time-domain wavelets
Description
Examples
DWT Filter Bank Wavelets
Create a seven-level DWT filter bank with a signal length of 1000 samples, using the Daubechies db2
wavelet and a sampling frequency of 1 kHz.
wv = "db4"; len = 1000; lev = 7; Fs = 1e3; fb = dwtfilterbank('Wavelet',wv,'SignalLength',len, ... 'Level',lev,'SamplingFrequency',Fs);
Plot the time-domain and centered wavelets corresponding to the wavelet bandpass filters.
[psi,t] = wavelets(fb); plot(t,psi') grid on title('Time-domain Wavelets')
Plot the finest scale time-domain wavelet and the one-sided magnitude frequency response of the corresponding wavelet bandpass filter.
sc = 1; [psidft,f] = freqz(fb); tiledlayout(2,1) nexttile plot(t,psi(sc,:)) grid on xlabel('Time (sec)') ylabel('Magnitude') title(['Level ',num2str(sc),' Time-Domain Wavelet']) nexttile plot(f(len/2:end),abs(psidft(sc,len/2:end))) grid on xlabel('Hz') ylabel('Magnitude') title('Magnitude Frequency Response')
Input Arguments
fb
— Discrete wavelet transform filter bank
dwtfilterbank
object
Discrete wavelet transform (DWT) filter bank, specified as a dwtfilterbank
object.
Output Arguments
psi
— Time-centered wavelets
real-valued matrix
Time-centered wavelets corresponding to the wavelet passband filters,
returned as an L-by-N matrix, where
L is the filter bank Level
and
N is the SignalLength
. The
wavelets are ordered in psi
from the finest scale
resolution to the coarsest scale resolution.
t
— Sampling instants
real-valued vector
Sampling instants, returned as a real-valued vector t
of length N, where N is the filter
bank SignalLength
. Sampling instants lie in the interval , where DT is the filter bank sampling
period (reciprocal of the filter bank sampling frequency).
Version History
Introduced in R2018a
See Also
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