IIRFilters::ChebyshevIFilter Function

IIRFilters Namespace

Overload List

#SignatureDescription
1double ChebyshevIFilter(int Order, double PassRipple, const DewArray<double> &CutoffFreq, TFilterType FilterType, bool Analog, TVec *z, TVec *p, double &k, TIirFrequencyTransform IirFrequencyTransform = TIirFrequencyTransform::ftStateSpaceAnalog);Design Chebyshev type I IIR filter.
2double ChebyshevIFilter(int Order, double PassRipple, const DewArray<double> &CutoffFreq, TFilterType FilterType, bool Analog, TVec *Num, TVec *Den, TIirFrequencyTransform IirFrequencyTransform = TIirFrequencyTransform::ftStateSpaceAnalog);The resulting transfer function is returned in the numerator/denumerator form with num and den.
3double ChebyshevIFilter(int Order, double PassRipple, const DewArray<double> &CutoffFreq, TFilterType FilterType, bool Analog, TVec *sos, TIirFrequencyTransform IirFrequencyTransform = TIirFrequencyTransform::ftStateSpaceAnalog);The resulting transfer function is returned in the second order section form stored in the sos variable.
4double ChebyshevIFilter(int Order, double PassRipple, const DewArray<double> &CutoffFreq, TFilterType FilterType, bool Analog, TMtx *A, TVec *B, TVec *C, double &d);The resulting transfer function is returned in the state-space form with A,B,C,D variables.

Overload 1: double ChebyshevIFilter(int Order, double PassRipple, const DewArray<double> &CutoffFreq, TFilterType FilterType, bool Analog, TVec *z, TVec *p, double &k, TIirFrequencyTransform IirFrequencyTransform = TIirFrequencyTransform::ftStateSpaceAnalog);

Design Chebyshev type I IIR filter.

#NameTypeDescription
1Orderint
2PassRippledouble
3CutoffFreqconst DewArray<double> &
4FilterTypeTFilterType
5Analogbool
6zTVec *
7pTVec *
8kdouble &
9IirFrequencyTransform = TIirFrequencyTransform::ftStateSpaceAnalogTIirFrequencyTransform
Remarks:

Design Chebyshev type I filter of Order with CutoffFreq frequencies and of FilterType type. Set Analog to True, to request and analog filter design in s-plane or set it to false to obtain a digital filter design in z-plane. PassRipple defines the passband ripple in dB. The CutoffFreq must be in range between 0 and 1 (Sampling frequency = 2) in case of a digital filter design.

IIrFrequencyTransform specifies when and how will the frequency band transformation be applied. The resulting transfer function is returned in the zero-pole form, with z,p,k variables.

Examples
#include "MtxExpr.h"
#include "Units.IIrFilters.h"
#include "Units.SignalUtils.h"

using namespace Dew;
using namespace Dew::Math;
using namespace Dew::Signal;
using namespace Dew::Signal::Units::IIRFilters;
using namespace Dew::Signal::Units::SignalUtils;

void Example()
{
    Vector z, p, num, den, FreqFr, Response;
    int Order;
    double k, Bw, Wc;
    DewArray<double> WcArray; //modified 3dB frequency

    WcArray.SetLength(2);
    Order = ChebyshevIOrder(DewArray<double>{1, 2, 5, 7}, 0.2, 50, TFilterType::ftBandpass, WcArray, true);
    ChebyshevIFilter(Order, 0.2, WcArray, TFilterType::ftBandpass, true, num, den);
    FreqFr.Length = 1000;         //Define the frequency grid (logarithmic)
    LogRamp(FreqFr, -1, 1); //between 0.1 (=10^(-1)) and 10 (=10^1) rad/sec
    FrequencyResponseS(num, den, FreqFr, Response); //Laplace

    //  Alternative: Design a digital filter with the passband between 0.2 and 0.5 Hz (FS =2)
    //    WcArray.SetLength(2);
    //    Order = ChebyshevIOrder(DewArray<double>{0.1, 0.2, 0.5, 0.6}, 0.2, 50, TFilterType::ftBandpass, WcArray, false);
    //    ChebyshevIFilter(Order, 0.2, WcArray, TFilterType::ftBandpass, false, num, den);
    //    FrequencyResponse(num, den, Response, 64);
    //    FreqFr.Size(Response.Length);
    //    FreqFr.Ramp(0, 1.0/FreqFr.Length);
}
Declared in Dew::Signal::Units::IIRFilters · Dew.Signal/Units.IIrFilters.h · Cross-compiler

Overload 2: double ChebyshevIFilter(int Order, double PassRipple, const DewArray<double> &CutoffFreq, TFilterType FilterType, bool Analog, TVec *Num, TVec *Den, TIirFrequencyTransform IirFrequencyTransform = TIirFrequencyTransform::ftStateSpaceAnalog);

The resulting transfer function is returned in the numerator/denumerator form with num and den.

#NameTypeDescription
1Orderint
2PassRippledouble
3CutoffFreqconst DewArray<double> &
4FilterTypeTFilterType
5Analogbool
6NumTVec *
7DenTVec *
8IirFrequencyTransform = TIirFrequencyTransform::ftStateSpaceAnalogTIirFrequencyTransform
Declared in Dew::Signal::Units::IIRFilters · Dew.Signal/Units.IIrFilters.h · Cross-compiler

Overload 3: double ChebyshevIFilter(int Order, double PassRipple, const DewArray<double> &CutoffFreq, TFilterType FilterType, bool Analog, TVec *sos, TIirFrequencyTransform IirFrequencyTransform = TIirFrequencyTransform::ftStateSpaceAnalog);

The resulting transfer function is returned in the second order section form stored in the sos variable.

#NameTypeDescription
1Orderint
2PassRippledouble
3CutoffFreqconst DewArray<double> &
4FilterTypeTFilterType
5Analogbool
6sosTVec *
7IirFrequencyTransform = TIirFrequencyTransform::ftStateSpaceAnalogTIirFrequencyTransform
Remarks:

The sos variable can be passed directly to the IirInitBQ filter initialization routine. Second order section form delivers substantially higher numerical stability and range than filtering with num/den form which is used by the IirInit routine.

Declared in Dew::Signal::Units::IIRFilters · Dew.Signal/Units.IIrFilters.h · Cross-compiler

Overload 4: double ChebyshevIFilter(int Order, double PassRipple, const DewArray<double> &CutoffFreq, TFilterType FilterType, bool Analog, TMtx *A, TVec *B, TVec *C, double &d);

The resulting transfer function is returned in the state-space form with A,B,C,D variables.

#NameTypeDescription
1Orderint
2PassRippledouble
3CutoffFreqconst DewArray<double> &
4FilterTypeTFilterType
5Analogbool
6ATMtx *
7BTVec *
8CTVec *
9ddouble &
Examples
#include "MtxExpr.h"
#include "Units.IIrFilters.h"
#include "Units.SignalUtils.h"

using namespace Dew;
using namespace Dew::Math;
using namespace Dew::Signal;
using namespace Dew::Signal::Units::IIRFilters;
using namespace Dew::Signal::Units::SignalUtils;

void Example()
{
    Vector num(0);
    Vector den(0);
    Vector Response(0);
    Vector FreqFr(0);
    DewArray<double> WcArray(2);

    //design analog filter
    int Order = ChebyshevIOrder(DewArray<double>{1, 2, 5, 7}, 0.2, 50, TFilterType::ftBandpass, WcArray, true);
    ChebyshevIFilter(Order, 0.2, WcArray, TFilterType::ftBandpass, true, num, den, TIirFrequencyTransform::ftStateSpaceAnalog);  //design analog protype
    FreqFr.Length = 1000;
    LogRamp(FreqFr, -1, 1);
    FrequencyResponseS(num, den, FreqFr, Response, 0);

    //Alternative: Design a digital filter with the passband between 0.2 and 0.5 Hz (FS =2)
    //Order = ChebyshevIOrder(DewArray<double>{0.1, 0.2, 0.5, 0.6}, 0.2, 50, TFilterType::ftBandpass, WcArray, false);
    //ChebyshevIFilter(Order, 0.2, WcArray, TFilterType::ftBandpass, false, num, den, TIirFrequencyTransform::ftStateSpaceAnalog);  //design digital protype
    //FrequencyResponse(num,den,Response,64);
    //FreqFr = Ramp(Response.Length, TMtxFloatPrecision::mvDouble, 0, 1.0 / Response.Length);
}
See Also: IirFilter, IIRFilters::ChebyshevIOrder, IIRFilters::ButterFilter, IIRFilters::ChebyshevIIFilter, IIRFilters::EllipticFilter, IIRFilters::BesselFilter
Declared in Dew::Signal::Units::IIRFilters · Dew.Signal/Units.IIrFilters.h · Cross-compiler