GNU Radio Manual and C++ API Reference  3.7.9.2
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iir_filter_ffd.h
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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,
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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
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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 
29 namespace gr {
30  namespace 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  */
66  class FILTER_API iir_filter_ffd : virtual public sync_block
67  {
68  public:
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 */
boost::shared_ptr< iir_filter_ffd > sptr
Definition: iir_filter_ffd.h:70
Include this header to use the message passing features.
Definition: logger.h:131
synchronous 1:1 input to output with historyOverride work to provide the signal processing implementa...
Definition: sync_block.h:37
#define FILTER_API
Definition: gr-filter/include/gnuradio/filter/api.h:30
IIR filter with float input, float output and double taps.
Definition: iir_filter_ffd.h:66