sysobj

Create filter System object from discrete-time filter

Syntax

hs = sysobj(hfilt)

Description

hs = sysobj(hfilt) creates a new filter System object™ hs from the dfilt object, hfilt.

The function supports a subset of dfilt objects. The following table lists supported filter structures for hfilt and the filter System object that the function creates.

Single-rate	Filter System object
Lattice AR(`dfilt.latticear`)	`dsp.AllpoleFilter`
Coupled-allpass, power-complementary lattice filter (`dfilt.calatticepc`)	`dsp.CoupledAllpassFilter`
Coupled-allpass, lattice filter (`dfilt.calattice`)	`dsp.CoupledAllpassFilter`
Cascade of discrete time filters (`dfilt.cascade`)	`dsp.FilterCascade`
Direct Form I (`dfilt.df1`)	`dsp.IIRFilter`
Direct Form I transposed (`dfilt.df1t`)	`dsp.IIRFilter`
Direct Form II (`dfilt.df2`)	`dsp.IIRFilter`
Direct Form II transposed (`dfilt.df2t`)	`dsp.IIRFilter`
Direct-form FIR (`dfilt.dffir`)	`dsp.FIRFilter`
Direct-form FIR transposed (`dfilt.dffirt`)	`dsp.FIRFilter`
Direct-form symmetric FIR (`dfilt.dfsymfir`)	`dsp.FIRFilter`
Direct-form antisymmetric FIR (`dfilt.dfasymfir`)	`dsp.FIRFilter`
Discrete-time, lattice, moving-average (`dfilt.latticemamin`)	`dsp.FIRFilter`
Discrete-time, second-order section, direct-form I (`dfilt.df1sos`)	`dsp.SOSFilter`
Discrete-time, second-order section, direct-form I transposed (`dfilt.df1tsos`)	`dsp.SOSFilter`
Discrete-time, second-order section, direct-form II (`dfilt.df2sos`)	`dsp.SOSFilter`
Discrete-time, second-order section, direct-form II transposed (`dfilt.df2tsos`)	`dsp.SOSFilter`

Input Arguments

hfilt

Discrete-time filter (dfilt) object. The preceding table lists supported filter structures.

If hfilt is a discrete-time filter with the PersistentMemory property set to true, then the filter states are copied into the initial conditions properties of hs. Otherwise, initial conditions are ignored.

The function does not support some dfilt properties for SOS filter structures.

If the CastBeforeSum property is set to false, the function issues a warning. The dsp.SOSFilter object always has a cast before a sum.
If the Signed property is false, the function issues a warning. The dsp.SOSFilter object does not support unsigned arithmetic.
The dsp.SOSFilter object does not support all the fixed point properties of the dfilt objects, but only the ones which are supported by the System object. For a complete list of these properties, see Fixed-Point Properties in the dsp.SOSFilter object page.

Output Arguments

hs

Filter System object. The function maps almost all properties of hfilt into the filter System object.

The function does not support some dfilt properties for SOS filter structures.

If the CastBeforeSum property is set to false, the function issues a warning. The dsp.SOSFilter object always has a cast before a sum.
If the Signed property is false, the function issues a warning. The dsp.SOSFilter object does not support unsigned arithmetic.
The dsp.SOSFilter object does not support all the fixed point properties of the dfilt objects, but only the ones which are supported by the System object. For a complete list of these properties, see Fixed-Point Properties in the dsp.SOSFilter object page.

Examples

collapse all

Convert a discrete-time filter object to a System object

hfilt = dfilt.df1sos; %Direct-form I SOS
hs = sysobj(hfilt)   %Biquadratic IIR filter

 dsp.SOSFilter with properties:

            Structure: 'Direct form I'
    CoefficientSource: 'Property'
            Numerator: [1 0 0]
          Denominator: [1 0 0]
       HasScaleValues: false

  Show all properties

Version History

Introduced in R2012a