convert

Convert filter structure of discrete-time filter

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Syntax

hq = convert(hq,newstruct)

Description

Discrete-Time Filters

hq = convert(hq,newstruct) returns a quantized filter whose structure has been transformed to the filter structure specified by newstruct. You can enter any one of the following quantized filter structures:

  • 'antisymmetricfir': Antisymmetric finite impulse response (FIR)

  • 'df1': Direct form I

  • 'df1t': Direct form I transposed

  • 'df1sos': Direct-Form I, Second-Order Sections

  • 'df1tsos': Direct-Form I Transposed, Second-Order Sections

  • 'df2': Direct form II

  • 'df2t': Direct form II transposed. Default filter structure

  • 'df2sos': Direct-Form II, Second-Order Sections

  • 'df2tsos': Direct-Form II Transposed, Second-Order Sections

  • 'dffir': FIR

  • 'dffirt': Direct form FIR transposed

  • 'latcallpass': Lattice allpass

  • 'latticeca': Lattice coupled-allpass

  • 'latticecapc': Lattice coupled-allpass power-complementary

  • 'latticear': Lattice autoregressive (AR)

  • 'latticemamax': Lattice moving average (MA) maximum phase

  • 'latticemamin': Lattice moving average (MA) minimum phase

  • 'latticearma': Lattice ARMA

  • 'statespace': Single-input/single-output state-space

  • 'symmetricfir': Symmetric FIR. Even and odd forms

All filters can be converted to the following structures:

  • 'df1': Direct form I

  • 'df1t': Direct form I transposed

  • 'df1sos': Direct-Form I, Second-Order Sections

  • 'df1tsos': Direct-Form I Transposed, Second-Order Sections

  • 'df2': Direct form II

  • 'df2t': Direct form II transposed. Default filter structure

  • 'df2sos': Direct-Form II, Second-Order Sections

  • 'df2tsos': Direct-Form II Transposed, Second-Order Sections

  • 'statespace': Single-input/single-output state-space

  • 'symmetricfir': Symmetric FIR. Even and odd forms

For the following filter classes, you can specify other conversions as well:

  • Minimum phase FIR filters can be converted to latticemamin

  • Maximum phase FIR filters can be converted to latticemamax

  • Allpass filters can be converted to latcallpass

convert generates an error when you specify a conversion that is not possible.

Examples

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[b,a]=ellip(5,3,40,.7); hq = dfilt.df2t(b,a)
hq = 
     FilterStructure: 'Direct-Form II Transposed'
          Arithmetic: 'double'                   
           Numerator: [1x6 double]               
         Denominator: [1x6 double]               
    PersistentMemory: false                      
                                                 

hq2 = convert(hq,'df1')
hq2 = 
     FilterStructure: 'Direct-Form I'
          Arithmetic: 'double'       
           Numerator: [1x6 double]   
         Denominator: [1x6 double]   
    PersistentMemory: false

Version History

Introduced in R2011a