dwtpassbands

R2026b

DWT filter bank passbands

Syntax

dwtbands = dwtpassbands(fb)

Description

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

Examples

DWT Filter Bank Passbands

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

fb — Discrete wavelet transform filter bank

dwtfilterbank object

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

Output Arguments

dwtbands — Theoretical DWT passbands

real-valued matrix

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.

Extended Capabilities

Thread-Based Environment

Run code in the background using MATLAB® backgroundPool or accelerate code with Parallel Computing Toolbox™ ThreadPool.

The dwtpassbands function fully supports thread-based environments. For more information, see Run MATLAB Functions in Thread-Based Environment.

Version History

Introduced in R2018a

R2026b: Use thread-based environments

You can use dwtpassbands in thread-based environments. For more information, see Run MATLAB Functions in Thread-Based Environment.