base class template for Infinite Impulse Response filter (IIR) More...

#include <gnuradio/filter/iir_filter.h>

Public Member Functions
	iir_filter (const std::vector< tap_type > &fftaps, const std::vector< tap_type > &fbtaps, bool oldstyle=true) throw (std::invalid_argument)
	Construct an IIR with the given taps. More...

	iir_filter ()

	~iir_filter ()

o_type	filter (const i_type input)
	compute a single output value. More...

void	filter_n (o_type output[], const i_type input[], long n)
	compute an array of N output values. `input` must have N valid entries. More...

unsigned	ntaps_ff () const

unsigned	ntaps_fb () const

void	set_taps (const std::vector< tap_type > &fftaps, const std::vector< tap_type > &fbtaps) throw (std::invalid_argument)
	install new taps. More...

template<>
gr_complex	filter (const gr_complex input)

template<>
gr_complex	filter (const gr_complex input)

template<>
gr_complex	filter (const gr_complex input)

Protected Attributes
bool	d_oldstyle

std::vector< tap_type >	d_fftaps

std::vector< tap_type >	d_fbtaps

int	d_latest_n

int	d_latest_m

std::vector< o_type >	d_prev_output

std::vector< i_type >	d_prev_input

Detailed Description

template<class i_type, class o_type, class tap_type>
class gr::filter::kernel::iir_filter< i_type, o_type, tap_type >

base class template for Infinite Impulse Response filter (IIR)

Constructor & Destructor Documentation

template<class i_type , class o_type , class tap_type >

gr::filter::kernel::iir_filter< i_type, o_type, tap_type >::iir_filter	(	const std::vector< tap_type > &	fftaps,
		const std::vector< tap_type > &	fbtaps,
		bool	oldstyle = `true`
	)
throw	(	std::invalid_argument
	)

inline

Construct an IIR with the given taps.

This filter uses the Direct Form I implementation, where fftaps contains the feed-forward taps, and fbtaps the feedback ones.

fftaps and fbtaps must have equal numbers of taps

oldstyle: The old style of the IIR filter uses feedback taps that are negative of what most definitions use (scipy and Matlab among them). This parameter keeps using the old GNU Radio style and is set to TRUE by default. When taps generated from scipy, Matlab, or gr_filter_design, use the new style by setting this to FALSE.

The input and output satisfy a difference equation of the form

$y[n] \pm \sum_{k=1}^{M} a_k y[n-k] = \sum_{k=0}^{N} b_k x[n-k]$

with the corresponding rational system function

$H(z) = \frac{\sum_{k=0}^{N} b_k z^{-k}}{1 \pm \sum_{k=1}^{M} a_k z^{-k}}$

References gr::filter::kernel::iir_filter< i_type, o_type, tap_type >::d_oldstyle, and gr::filter::kernel::iir_filter< i_type, o_type, tap_type >::set_taps().

template<class i_type , class o_type , class tap_type >

gr::filter::kernel::iir_filter< i_type, o_type, tap_type >::iir_filter ( )

inline

template<class i_type , class o_type , class tap_type >

gr::filter::kernel::iir_filter< i_type, o_type, tap_type >::~iir_filter ( )

inline

Member Function Documentation

template<class i_type , class o_type , class tap_type >

o_type gr::filter::kernel::iir_filter< i_type, o_type, tap_type >::filter ( const i_type input )

compute a single output value.

Returns: the filtered input value.

template<>

gr_complex gr::filter::kernel::iir_filter< gr_complex, gr_complex, float >::filter ( const gr_complex input )

template<>

gr_complex gr::filter::kernel::iir_filter< gr_complex, gr_complex, double >::filter ( const gr_complex input )

template<>

gr_complex gr::filter::kernel::iir_filter< gr_complex, gr_complex, gr_complexd >::filter ( const gr_complex input )

template<class i_type , class o_type , class tap_type >

void gr::filter::kernel::iir_filter< i_type, o_type, tap_type >::filter_n	(	o_type	output[],
		const i_type	input[],
		long	n
	)

compute an array of N output values. input must have N valid entries.

template<class i_type , class o_type , class tap_type >

unsigned gr::filter::kernel::iir_filter< i_type, o_type, tap_type >::ntaps_fb ( ) const

inline

References gr::filter::kernel::iir_filter< i_type, o_type, tap_type >::d_fbtaps.

template<class i_type , class o_type , class tap_type >

unsigned gr::filter::kernel::iir_filter< i_type, o_type, tap_type >::ntaps_ff ( ) const

inline

Returns: number of taps in filter.

References gr::filter::kernel::iir_filter< i_type, o_type, tap_type >::d_fftaps.

template<class i_type , class o_type , class tap_type >

void gr::filter::kernel::iir_filter< i_type, o_type, tap_type >::set_taps	(	const std::vector< tap_type > &	fftaps,
		const std::vector< tap_type > &	fbtaps
	)
throw	(	std::invalid_argument
	)