GNU Radio Manual and C++ API Reference 3.7.14.0
The Free & Open Software Radio Ecosystem
iir_filter_ffd.h
Go to the documentation of this file.
1/* -*- c++ -*- */
2/*
3 * Copyright 2004,2012 Free Software Foundation, Inc.
4 *
5 * This file is part of GNU Radio
6 *
7 * GNU Radio is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; either version 3, or (at your option)
10 * any later version.
11 *
12 * GNU Radio is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
16 *
17 * You should have received a copy of the GNU General Public License
18 * along with GNU Radio; see the file COPYING. If not, write to
19 * the Free Software Foundation, Inc., 51 Franklin Street,
20 * Boston, MA 02110-1301, USA.
21 */
22
23#ifndef INCLUDED_IIR_FILTER_FFD_H
24#define INCLUDED_IIR_FILTER_FFD_H
25
26#include <gnuradio/filter/api.h>
27#include <gnuradio/sync_block.h>
28
29namespace gr {
30namespace filter {
31
32/*!
33 * \brief IIR filter with float input, float output and double taps
34 * \ingroup filter_blk
35 *
36 * \details
37 * This filter uses the Direct Form I implementation, where
38 * \p fftaps contains the feed-forward taps, and \p fbtaps the feedback ones.
39 *
40 * \p oldstyle: The old style of the IIR filter uses feedback
41 * taps that are negative of what most definitions use (scipy
42 * and Matlab among them). This parameter keeps using the old
43 * GNU Radio style and is set to TRUE by default. When taps
44 * generated from scipy, Matlab, or gr_filter_design, use the
45 * new style by setting this to FALSE.
46 *
47 * The input and output satisfy a difference equation of the form
48 \f[
49 y[n] - \sum_{k=1}^{M} a_k y[n-k] = \sum_{k=0}^{N} b_k x[n-k]
50 \f]
51
52 \xmlonly
53 y[n] - \sum_{k=1}^{M} a_k y[n-k] = \sum_{k=0}^{N} b_k x[n-k]
54 \endxmlonly
55
56 * with the corresponding rational system function
57 \f[
58 H(z) = \frac{\sum_{k=0}^{M} b_k z^{-k}}{1 - \sum_{k=1}^{N} a_k z^{-k}}
59 \f]
60
61 \xmlonly
62 H(z) = \ frac{\sum_{k=0}^{M} b_k z^{-k}}{1 - \sum_{k=1}^{N} a_k z^{-k}}
63 \endxmlonly
64
65 */
66class FILTER_API iir_filter_ffd : virtual public sync_block
67{
68public:
69 // gr::filter::iir_filter_ffd::sptr
70 typedef boost::shared_ptr<iir_filter_ffd> sptr;
71
72 static sptr make(const std::vector<double>& fftaps,
73 const std::vector<double>& fbtaps,
74 bool oldstyle = true);
75
76 virtual void set_taps(const std::vector<double>& fftaps,
77 const std::vector<double>& fbtaps) = 0;
78};
79
80} /* namespace filter */
81} /* namespace gr */
82
83#endif /* INCLUDED_IIR_FILTER_FFD_H */
IIR filter with float input, float output and double taps.
Definition: iir_filter_ffd.h:67
static sptr make(const std::vector< double > &fftaps, const std::vector< double > &fbtaps, bool oldstyle=true)
boost::shared_ptr< iir_filter_ffd > sptr
Definition: iir_filter_ffd.h:70
virtual void set_taps(const std::vector< double > &fftaps, const std::vector< double > &fbtaps)=0
synchronous 1:1 input to output with history
Definition: sync_block.h:38
#define FILTER_API
Definition: gr-filter/include/gnuradio/filter/api.h:30
Include this header to use the message passing features.
Definition: basic_block.h:45