r8b::CDSPSincFilterGen Class Reference

Sinc function-based FIR filter generator class. More...

#include <CDSPSincFilterGen.h>

Public Types
typedef double(CDSPSincFilterGen ::*	CWindowFunc) ()
	Window calculation function pointer type.
enum	EWindowFunctionType { wftCosine , wftKaiser , wftGaussian }

Public Member Functions
double	calcWindowBlackman ()
double	calcWindowBlackmanNuttall ()
double	calcWindowGaussian ()
double	calcWindowHamming ()
double	calcWindowHann ()
double	calcWindowKaiser ()
double	calcWindowNuttall ()
void	generateBand (double *op, CWindowFunc wfunc=&CDSPSincFilterGen ::calcWindowBlackman)
void	generateFrac (double *op, CWindowFunc wfunc=&CDSPSincFilterGen ::calcWindowBlackman, const int opinc=1)
void	generateHilbert (double *op, CWindowFunc wfunc=&CDSPSincFilterGen ::calcWindowBlackman)
void	generateWindow (double *op, CWindowFunc wfunc=&CDSPSincFilterGen ::calcWindowBlackman)
void	initBand (const EWindowFunctionType WinType=wftCosine, const double *const Params=NULL, const bool UsePower=false)
void	initFrac (const EWindowFunctionType WinType=wftCosine, const double *const Params=NULL, const bool UsePower=false)
void	initHilbert (const EWindowFunctionType WinType=wftCosine, const double *const Params=NULL, const bool UsePower=false)
void	initWindow (const EWindowFunctionType WinType=wftCosine, const double *const Params=NULL, const bool UsePower=false)

Public Attributes
union {
struct {
double   Freq1
	Required corner circular frequency 1 [0; pi]. Used only in the generateBand() function.
double   Freq2
	Required corner circular frequency 2 [0; pi]. Used only in the generateBand() function. The range [Freq1; Freq2] defines a pass band for the generateBand() function.
}
struct {
double   FracDelay
	Fractional delay in the range [0; 1], used only in the generateFrac() function. Note that the FracDelay parameter is actually inversed. At 0.0 value it produces 1 sample delay (with the latency equal to fl2), at 1.0 value it produces 0 sample delay (with the latency equal to fl2 - 1).
}
};
int	fl2
	Internal "half kernel length" value. This value can be used as filter's latency in samples (taps), this variable is set after the call to one of the "init" functions.
int	KernelLen
	Resulting length of the filter kernel, this variable is set after the call to one of the "init" functions.
double	Len2
	Required half filter kernel's length in samples (can be a fractional value). Final physical kernel length will be provided in the KernelLen variable. Len2 should be >= 2.
double	Len2i
	= 1.0 / Len2, initialized and used by some window functions for optimization (should not be initialized by the caller).
double	GaussianSigmaFrac
	Equals FracDelay / GaussianSigma.
double	GaussianSigmaI
	Gaussian window function's "Sigma" coefficient, inverse.
double	KaiserBeta
	Kaiser window function's "Beta" coefficient.
double	KaiserLen2Frac
	Equals FracDelay / Len2.
double	KaiserMul
	Kaiser window function's divisor, inverse.

Detailed Description

Sinc function-based FIR filter generator class.

Structure that holds state used to perform generation of sinc functions of various types, windowed by the Blackman window by default (but the window function can be changed if necessary).

Member Enumeration Documentation

EWindowFunctionType

enum r8b::CDSPSincFilterGen::EWindowFunctionType

Window function type.

Enumerator
wftCosine	Generalized cosine window function. No parameters required. The "Power" parameter is optional.
wftKaiser	Kaiser window function. Requires the "Beta" parameter. The "Power" parameter is optional.
wftGaussian	Gaussian window function. Requires the "Sigma" parameter. The "Power" parameter is optional.

Member Function Documentation

calcWindowBlackman()

double r8b::CDSPSincFilterGen::calcWindowBlackman

(

)

Returns

The next "Blackman" window function coefficient.

calcWindowBlackmanNuttall()

double r8b::CDSPSincFilterGen::calcWindowBlackmanNuttall

(

)

Returns

The next "Blackman-Nuttall" window function coefficient.

calcWindowGaussian()

double r8b::CDSPSincFilterGen::calcWindowGaussian

(

)

Returns

The next "Gaussian" window function coefficient.

calcWindowHamming()

double r8b::CDSPSincFilterGen::calcWindowHamming

(

)

Returns

The next "Hamming" window function coefficient.

calcWindowHann()

double r8b::CDSPSincFilterGen::calcWindowHann

(

)

Returns

The next "Hann" window function coefficient.

calcWindowKaiser()

double r8b::CDSPSincFilterGen::calcWindowKaiser

(

)

Returns

The next "Kaiser" window function coefficient.

calcWindowNuttall()

double r8b::CDSPSincFilterGen::calcWindowNuttall

(

)

Returns

The next "Nuttall" window function coefficient.

generateBand()

void r8b::CDSPSincFilterGen::generateBand	(	double *	op,
		CWindowFunc	wfunc = &CDSPSincFilterGen :: calcWindowBlackman
	)

Function calculates band-limited windowed sinc function-based filter kernel.

Parameters

[out]	op	Output buffer, length = KernelLen.
	wfunc	Window calculation function to use.

generateFrac()

void r8b::CDSPSincFilterGen::generateFrac	(	double *	op,
		CWindowFunc	wfunc = &CDSPSincFilterGen :: calcWindowBlackman,
		const int	opinc = 1
	)

Function calculates windowed fractional delay filter kernel.

Parameters

[out]	op	Output buffer, length = KernelLen.
	wfunc	Window calculation function to use.
	opinc	Output buffer increment, in "op" elements.

generateHilbert()

void r8b::CDSPSincFilterGen::generateHilbert	(	double *	op,
		CWindowFunc	wfunc = &CDSPSincFilterGen :: calcWindowBlackman
	)

Function calculates windowed Hilbert transformer filter kernel.

Parameters

[out]	op	Output buffer, length = KernelLen.
	wfunc	Window calculation function to use.

generateWindow()

void r8b::CDSPSincFilterGen::generateWindow	(	double *	op,
		CWindowFunc	wfunc = &CDSPSincFilterGen :: calcWindowBlackman
	)

Function calculates window function only.

Parameters

[out]	op	Output buffer, length = KernelLen.
	wfunc	Window calculation function to use.

initBand()

void r8b::CDSPSincFilterGen::initBand	(	const EWindowFunctionType	WinType = wftCosine,
		const double *const	Params = NULL,
		const bool	UsePower = false
	)

Function initializes *this structure for generation of band-limited sinc filter kernel. The generateBand() function should be used to calculate the filter.

Parameters

WinType	Window function type.
Params	Window function's parameters. If NULL, the table values may be used.
UsePower	"True" if the power factor should be used to raise the window function. If "true", the power factor should be specified as the last value in the Params array. If Params is NULL, the table or default value of -1.0 (off) will be used.

initFrac()

void r8b::CDSPSincFilterGen::initFrac	(	const EWindowFunctionType	WinType = wftCosine,
		const double *const	Params = NULL,
		const bool	UsePower = false
	)

Function initializes *this structure for generation of full-bandwidth fractional delay sinc filter kernel. Freq1 and Freq2 variables are not used. The generateFrac() function should be used to calculate the filter.

Parameters

WinType	Window function type.
Params	Window function's parameters. If NULL, the table values may be used.
UsePower	"True" if the power factor should be used to raise the window function. If "true", the power factor should be specified as the last value in the Params array. If Params is NULL, the table or default value of -1.0 (off) will be used.

initHilbert()

void r8b::CDSPSincFilterGen::initHilbert	(	const EWindowFunctionType	WinType = wftCosine,
		const double *const	Params = NULL,
		const bool	UsePower = false
	)

Function initializes *this structure for Hilbert transformation filter calculation. Freq1 and Freq2 variables are not used. The generateHilbert() function should be used to calculate the filter.

Parameters

WinType	Window function type.
Params	Window function's parameters. If NULL, the table values may be used.
UsePower	"True" if the power factor should be used to raise the window function. If "true", the power factor should be specified as the last value in the Params array. If Params is NULL, the table or default value of -1.0 (off) will be used.

initWindow()

void r8b::CDSPSincFilterGen::initWindow	(	const EWindowFunctionType	WinType = wftCosine,
		const double *const	Params = NULL,
		const bool	UsePower = false
	)

Function initializes *this structure for generation of a window function, odd-sized.

Parameters

WinType	Window function type.
Params	Window function's parameters. If NULL, the table values may be used.
UsePower	"True" if the power factor should be used to raise the window function. If "true", the power factor should be specified as the last value in the Params array. If Params is NULL, the table or default value of -1.0 (off) will be used.