polyphase - Polyphase decomposition of multirate filter

Syntax

p = polyphase(hm) polyphase(hm)

Description

p = polyphase(hm) returns the polyphase matrix p of the multirate filter hm. Each row in the matrix represents one subfilter of the multirate filter. The first row of matrix p represents the first subfilter, the second row the second subfilter, and so on to the last subfilter.

polyphase(hm) called with no output argument launches the Filter Visualization Tool (FVTool) with all the polyphase subfilters to allow you to analyze each component subfilter individually.

Examples

When you create a multirate filter that uses polyphase decomposition, polyphase lets you analyze the component filters individually by returning the components as rows in a matrix.

This example creates an interpolate by eight filter.

hm=mfilt.firinterp(8)
 
hm =
 
         FilterStructure: 'Direct-Form FIR Polyphase Interpolator'
               Numerator: [1x192 double]
     InterpolationFactor: 8
        PersistentMemory: false
                  States: [23x1 double]

In this syntax, the matrix p contains all of the subfilters for hm, one filter per matrix row.

p=polyphase(hm)

p =

  Columns 1 through 8 

         0         0         0         0         0         0         0         0
   -0.0000    0.0002   -0.0006    0.0013   -0.0026    0.0048   -0.0081    0.0133
   -0.0001    0.0004   -0.0012    0.0026   -0.0052    0.0094   -0.0160    0.0261
   -0.0001    0.0006   -0.0017    0.0038   -0.0074    0.0132   -0.0223    0.0361
   -0.0002    0.0008   -0.0020    0.0045   -0.0086    0.0153   -0.0257    0.0415
   -0.0002    0.0008   -0.0021    0.0045   -0.0086    0.0151   -0.0252    0.0406
   -0.0002    0.0007   -0.0018    0.0038   -0.0071    0.0124   -0.0205    0.0330
   -0.0001    0.0004   -0.0011    0.0022   -0.0041    0.0072   -0.0118    0.0189

  Columns 9 through 16 

         0         0         0         0    1.0000         0         0         0
   -0.0212    0.0342   -0.0594    0.1365    0.9741   -0.1048    0.0511   -0.0303
   -0.0416    0.0673   -0.1189    0.2958    0.8989   -0.1730    0.0878   -0.0527
   -0.0576    0.0938   -0.1691    0.4659    0.7814   -0.2038    0.1071   -0.0648
   -0.0661    0.1084   -0.2003    0.6326    0.6326   -0.2003    0.1084   -0.0661
   -0.0648    0.1071   -0.2038    0.7814    0.4659   -0.1691    0.0938   -0.0576
   -0.0527    0.0878   -0.1730    0.8989    0.2958   -0.1189    0.0673   -0.0416
   -0.0303    0.0511   -0.1048    0.9741    0.1365   -0.0594    0.0342   -0.0212

  Columns 17 through 24 

         0         0         0         0         0         0         0         0
    0.0189   -0.0118    0.0072   -0.0041    0.0022   -0.0011    0.0004   -0.0001
    0.0330   -0.0205    0.0124   -0.0071    0.0038   -0.0018    0.0007   -0.0002
    0.0406   -0.0252    0.0151   -0.0086    0.0045   -0.0021    0.0008   -0.0002
    0.0415   -0.0257    0.0153   -0.0086    0.0045   -0.0020    0.0008   -0.0002
    0.0361   -0.0223    0.0132   -0.0074    0.0038   -0.0017    0.0006   -0.0001
    0.0261   -0.0160    0.0094   -0.0052    0.0026   -0.0012    0.0004   -0.0001
    0.0133   -0.0081    0.0048   -0.0026    0.0013   -0.0006    0.0002   -0.0000

Finally, using polyphase without an output argument opens the Filter Visualization Tool, ready for you to use the analysis capabilities of the tool to investigate the interpolator hm.

polyphase(hm)

In the following figure, FVTool shows the magnitude responses for the subfilters.

polyphase - Polyphase decomposition of multirate filter

Syntax

Description

Examples

See Also