UTILSLIB::FirFilter Class Reference

Discoverable façade over the FilterKernel FIR-filter engine. More...

#include <firfilter.h>

Public Types
enum	FilterType { LowPass = 0 , HighPass = 1 , BandPass = 2 , BandStop = 3 }
	FIR filter type — mirrors IirFilter::FilterType for a uniform API. More...
enum	DesignMethod { Cosine = 0 , ParksMcClellan = 1 }
	FIR design method — wraps FilterKernel's iDesignMethod integer codes. More...

Static Public Member Functions
static FilterKernel	design (int iOrder, FilterType type, double dCutoffLow, double dCutoffHigh, double dSFreq, double dTransition=5.0, DesignMethod method=Cosine)
static Eigen::RowVectorXd	apply (const Eigen::RowVectorXd &vecData, FilterKernel &kernel)
static Eigen::RowVectorXd	applyZeroPhase (const Eigen::RowVectorXd &vecData, FilterKernel &kernel)
static Eigen::MatrixXd	applyZeroPhaseMatrix (const Eigen::MatrixXd &matData, FilterKernel &kernel, const Eigen::RowVectorXi &vecPicks=Eigen::RowVectorXi())

Detailed Description

Discoverable façade over the FilterKernel FIR-filter engine.

Quick-start example — mirrors the IirFilter API:

// Design a 256-tap band-pass filter
FilterKernel bpf = FirFilter::design(256, FirFilter::BandPass, 1.0, 40.0, sFreq);
 
// Apply to a single row vector (group delay already removed — symmetric FIR)
Eigen::RowVectorXd out = FirFilter::apply(vecData, bpf);
 
// Apply to all rows of a matrix
Eigen::MatrixXd clean = FirFilter::applyZeroPhaseMatrix(matData, bpf);

Definition at line 79 of file firfilter.h.

Member Enumeration Documentation

DesignMethod

enum UTILSLIB::FirFilter::DesignMethod

FIR design method — wraps FilterKernel's iDesignMethod integer codes.

Enumerator
Cosine	Cosine window (fast, moderate roll-off).
ParksMcClellan	Equiripple Parks-McClellan (optimal minimax).

Definition at line 97 of file firfilter.h.

FilterType

enum UTILSLIB::FirFilter::FilterType

FIR filter type — mirrors IirFilter::FilterType for a uniform API.

Enumerator
LowPass	Low-pass filter.
HighPass	High-pass filter.
BandPass	Band-pass filter.
BandStop	Band-stop (notch) filter.

Definition at line 86 of file firfilter.h.

Member Function Documentation

apply()

RowVectorXd FirFilter::apply ( const Eigen::RowVectorXd & vecData, FilterKernel & kernel )

static

Apply the filter to a single row vector.

Uses overlap-add FFT convolution. The group delay of a symmetric FIR is removed by the FilterKernel engine (it takes the output segment starting at order/2), so the result is already approximately zero-phase for symmetric designs.

Parameters

[in]	vecData	Input row vector.
[in,out]	kernel	FilterKernel (prepareFilter is called if needed).

Returns

Filtered row vector (same length as input).

Definition at line 121 of file firfilter.cpp.

applyZeroPhase()

RowVectorXd FirFilter::applyZeroPhase ( const Eigen::RowVectorXd & vecData, FilterKernel & kernel )

static

Apply the filter in a zero-phase forward-backward pass to a single row vector.

Runs the filter twice (forward then reverse) to achieve exactly zero phase shift. Effective order is doubled; transition bandwidth is halved.

Parameters

[in]	vecData	Input row vector.
[in,out]	kernel	FilterKernel.

Returns

Zero-phase filtered row vector.

Definition at line 131 of file firfilter.cpp.

applyZeroPhaseMatrix()

MatrixXd FirFilter::applyZeroPhaseMatrix ( const Eigen::MatrixXd & matData, FilterKernel & kernel, const Eigen::RowVectorXi & vecPicks = Eigen::RowVectorXi() )

static

Apply the filter in a zero-phase forward-backward pass to every row of a matrix.

Parameters

[in]	matData	Input matrix (n_channels × n_samples).
[in,out]	kernel	FilterKernel.
[in]	vecPicks	Optional row indices to filter; if empty, all rows are filtered.

Returns

Zero-phase filtered matrix (same dimensions as input).

Definition at line 147 of file firfilter.cpp.

design()

FilterKernel FirFilter::design ( int iOrder, FilterType type, double dCutoffLow, double dCutoffHigh, double dSFreq, double dTransition = 5.0, DesignMethod method = Cosine )

static

Design a linear-phase FIR filter using FilterKernel as the backend.

Frequencies are given in Hz; the method converts them to the Nyquist-normalised form expected by FilterKernel internally.

Parameters

[in]	iOrder	Filter order (number of taps − 1). Must be even for linear phase.
[in]	type	Filter type (LowPass, HighPass, BandPass, BandStop).
[in]	dCutoffLow	Lower cutoff frequency in Hz. For LowPass/HighPass: the single cutoff. For BandPass/BandStop: lower edge of the transition band.
[in]	dCutoffHigh	Upper cutoff frequency in Hz (ignored for LowPass/HighPass).
[in]	dSFreq	Sampling frequency in Hz.
[in]	dTransition	Width of the transition band in Hz (Parks-McClellan steepness / Cosine roll-off width). Defaults to 5 Hz.
[in]	method	Design method (Cosine or ParksMcClellan).

Returns

A ready-to-use FilterKernel object.

Definition at line 63 of file firfilter.cpp.

---

The documentation for this class was generated from the following files:

• src/libraries/dsp/firfilter.h
• src/libraries/dsp/firfilter.cpp