filterkernel.h File Reference

Linear-phase FIR filter kernel with overlap-add FFT convolution back-end. More...

#include "dsp_global.h"
#include <Eigen/Core>
#include <QString>
#include <QMetaType>
#include <QVector>
#include <QDebug>

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Classes
class	UTILSLIB::FilterParameter
	Named filter-design parameter descriptor holding a human-readable name and description (e.g. design method or filter type). More...
class	UTILSLIB::FilterKernel
	The FilterKernel class provides methods to create/design a FIR filter kernel. More...

Namespaces
namespace	UTILSLIB
	Shared utilities (I/O helpers, spectral analysis, layout management, warp algorithms).

Macros
#define	metatype_filterkernel
#define	metatype_filterkernel

Detailed Description

Linear-phase FIR filter kernel with overlap-add FFT convolution back-end.

SPDX-License-Identifier: BSD-3-Clause Copyright (c) 2026 MNE-CPP Authors

Author

Christoph Dinh chris.nosp@m.toph.nosp@m..dinh.nosp@m.@mne.nosp@m.-cpp..nosp@m.org

Since

2.0.0

Date

March 2026

FilterKernel is the core FIR engine of the DSP library: it owns the impulse response coefficients of a low-pass, high-pass, band-pass or notch filter together with their zero-padded FFT and applies them to incoming data via overlap-add convolution. Two design back-ends are supported — the cosine-tapered raised-cosine design (UTILSLIB::CosineFilter, fast, smooth roll-off) and the Parks–McClellan equiripple design (UTILSLIB::ParksMcClellan, optimal minimax behaviour). Both produce Type-I linear-phase responses, so the kernel can be applied either as a single forward pass with a fixed group delay of (NumTaps-1)/2 samples or in zero-phase forward / time-reverse mode.

Frequency-domain convolution is realised by zero-padding the impulse response to the next power of two, transforming once at design time and caching the result. Each input block of length FFTLength − NumTaps is then transformed, multiplied with the cached spectrum and inverse- transformed; consecutive blocks are stitched by adding the NumTaps − 1 tail of the preceding block to the head of the next, which suppresses circular-convolution artefacts. Typical example: with FFTLength = 4096 and NumTaps = 80 the useful per-block input length is 4016 samples.

References: [1] https://en.wikipedia.org/wiki/Parks%E2%80%93McClellan_filter_design_algorithm [2] https://en.wikipedia.org/wiki/Overlap%E2%80%93add_method

Definition in file filterkernel.h.

Macro Definition Documentation

metatype_filterkernel [1/2]

#define metatype_filterkernel

Definition at line 272 of file filterkernel.h.

metatype_filterkernel [2/2]

#define metatype_filterkernel

Definition at line 272 of file filterkernel.h.