Overload List
| # | Signature | Description |
|---|---|---|
| 1 | double BesselFilter(int Order, const DewArray<double> &CutoffFreq, TFilterType FilterType, bool Analog, TVec *z, TVec *p, double &k, TIirFrequencyTransform IirFrequencyTransform = TIirFrequencyTransform::ftStateSpaceAnalog); | Design Bessel IIR filter. |
| 2 | double BesselFilter(int Order, 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. |
| 3 | double BesselFilter(int Order, 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 BesselFilter(int Order, const DewArray<double> &CutoffFreq, TFilterType FilterType, bool Analog, TVec *z, TVec *p, double &k, TIirFrequencyTransform IirFrequencyTransform = TIirFrequencyTransform::ftStateSpaceAnalog);
Design Bessel IIR filter.
| # | Name | Type | Description |
|---|---|---|---|
| 1 | Order | int | |
| 2 | CutoffFreq | const DewArray<double> & | |
| 3 | FilterType | TFilterType | |
| 4 | Analog | bool | |
| 5 | z | TVec * | |
| 6 | p | TVec * | |
| 7 | k | double & | |
| 8 | IirFrequencyTransform = TIirFrequencyTransform::ftStateSpaceAnalog | TIirFrequencyTransform |
Remarks:
Design Bessel filter of Order with CutoffFreq frequencies and of FilterType type. Set Analog to True, to request an analog filter design in s-plane or set it to false to obtain a digital filter design in z-plane. CutoffFreq must be in range between 0 and 1 (Sampling frequency = 2).
IIrFrequencyTransform specifies when and how will the frequency band transformation be applied. Bessel filters typically do not preserve a flat group delay once transformed to z-domain. The routine uses bilinear transformation to map from s to z-domain. Use matched-Z transform to preserve more phase properties of the Bessel filters in the z-domain. 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
BesselFilter(5, DewArray<double>{3}, TFilterType::ftLowpass, 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
}Declared in Dew::Signal::Units::IIRFilters · Dew.Signal/Units.IIrFilters.h · Cross-compiler
Overload 2: double BesselFilter(int Order, 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.
| # | Name | Type | Description |
|---|---|---|---|
| 1 | Order | int | |
| 2 | CutoffFreq | const DewArray<double> & | |
| 3 | FilterType | TFilterType | |
| 4 | Analog | bool | |
| 5 | Num | TVec * | |
| 6 | Den | TVec * | |
| 7 | IirFrequencyTransform = TIirFrequencyTransform::ftStateSpaceAnalog | TIirFrequencyTransform |
Declared in Dew::Signal::Units::IIRFilters · Dew.Signal/Units.IIrFilters.h · Cross-compiler
Overload 3: double BesselFilter(int Order, 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.
| # | Name | Type | Description |
|---|---|---|---|
| 1 | Order | int | |
| 2 | CutoffFreq | const DewArray<double> & | |
| 3 | FilterType | TFilterType | |
| 4 | Analog | bool | |
| 5 | A | TMtx * | |
| 6 | B | TVec * | |
| 7 | C | TVec * | |
| 8 | d | double & |
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);
BesselFilter(5, DewArray<double>{3}, TFilterType::ftLowpass, true, num, den, TIirFrequencyTransform::ftStateSpaceAnalog); //design analog protype
FreqFr.Length = 1000;
LogRamp(FreqFr, -1, 1);
FrequencyResponseS(num, den, FreqFr, Response, 0);
}See Also: IirFilter, IIRFilters::ButterFilter, IIRFilters::ChebyshevIFilter, IIRFilters::ChebyshevIIFilter, IIRFilters::EllipticFilter, IIRFilters::BesselAnalog, Bilinear, IIRFilters::ButterOrder
Declared in Dew::Signal::Units::IIRFilters · Dew.Signal/Units.IIrFilters.h · Cross-compiler