Filter Design Toolbox

convert

Convert filter structures of quantized filters

Syntax

• hq = convert(hq,newstruct)
  

Description

hq = convert(hq,newstruct) returns a quantized filter whose structure has been transformed to the filter structure specified by string 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.
• 'df2': Direct form II.
• 'df2t': Direct form II transposed. Default filter structure.
• 'fir': FIR.
• 'firt': Direct form FIR transposed.
• 'latcallpass': Lattice allpass.
• 'latticeca': Lattice coupled-allpass.
• 'latticecapc': Lattice coupled-allpass power-complementary.
• 'latticear': Lattice autoregressive (AR).
• 'latticema': Lattice moving average (MA) minimum phase.
• 'latcmax': Lattice moving average (MA) maximum 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
• df1t
• df2
• df2t
• statespace
• latticearma

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

• Minimum phase FIR filters can be converted to latticema
• Maximum phase FIR filters can be converted to latcmax
• Allpass filters can be converted to latcallpass

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

Examples

• [b,a]=ellip(5,3,40,.7);
  hq = qfilt('df2t',{b,a});
  hq2 = convert(hq,'statespace')
  hq2 = 
  Quantized State-space filter 
  .
  .
  .
  FilterStructure = statespace                                       
         ScaleValues = [1]                                              
    NumberOfSections = 1                                                
    StatesPerSection = [5]                                              
   CoefficientFormat = quantizer('fixed', 'round', 'saturate', [16  15])
         InputFormat = quantizer('fixed', 'floor', 'saturate', [16  15])
        OutputFormat = quantizer('fixed', 'floor', 'saturate', [16  15])
  MultiplicandFormat = quantizer('fixed', 'floor', 'saturate', [16  15])
       ProductFormat = quantizer('fixed', 'floor', 'saturate', [32  30])
           SumFormat = quantizer('fixed', 'floor', 'saturate', [32  30])
  Warning: 9 overflows in coefficients.
  

See Also
qfilt

convergent

copyobj