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dwtpassbands

DWT filter bank passbands

Description

example

dwtbands = dwtpassbands(fb) returns the theoretical discrete wavelet transform (DWT) passbands for the DWT filter bank fb.

Examples

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Obtain the theoretical DWT passbands for a four-level wavelet transform using the Daubechies db6 wavelet with a sampling frequency of 1 kHz.

wv = 'db6';
Fs = 1e3;
fb = dwtfilterbank('Wavelet',wv,'Level',4,'SamplingFrequency',Fs);
dwtpassbands(fb)
ans = 5×2

  250.0000  500.0000
  125.0000  250.0000
   62.5000  125.0000
   31.2500   62.5000
         0   31.2500

Obtain the power bandwidths for the filter bank. Compare the theoretical passbands with the measured wavelet 3 dB bandwidths at all four levels.

ptable = powerbw(fb);
ptable(:,1:3)
ans=4×3 table
    Level       DWTBand        Wavelet3dBBandwidth
    _____    ______________    ___________________

      1        250      500        250       500  
      2        125      250      123.2    253.71  
      3       62.5      125     61.601    126.78  
      4      31.25     62.5     30.815    63.389  

Input Arguments

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Discrete wavelet transform (DWT) filter bank, specified as a dwtfilterbank object.

Output Arguments

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Theoretical DWT passbands for the filter bank fb, returned as an L+1-by-2 real-valued matrix, where L is the wavelet transform level of the filter bank.

  • The first L rows of dwtbands contain the theoretical passband frequencies for the DWT listed in order of decreasing resolution (increasing scale).

  • The final row of dwtbands contains the theoretical passband for the coarsest resolution scaling filter.

  • The first column of dwtbands contains the lower frequency limit.

  • The final row of dwtbands contains the theoretical passband for the coarsest resolution scaling filter.

Introduced in R2018a