GNU Radio 3.7.2 C++ API
iir_filter_ffd.h
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1 /* -*- c++ -*- */
2 /*
3  * Copyright 2004,2012 Free Software Foundation, Inc.
4  *
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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  \htmlonly
49  \f{
50  y[n] - \sum_{k=1}^{M} a_k y[n-k] = \sum_{k=0}^{N} b_k x[n-k]
51  \f}
52  \endhtmlonly
53 
54  \xmlonly
55  y[n] - \sum_{k=1}^{M} a_k y[n-k] = \sum_{k=0}^{N} b_k x[n-k]
56  \endxmlonly
57 
58  * with the corresponding rational system function
59  \htmlonly
60  \f{
61  H(z) = \ frac{\sum_{k=0}^{M} b_k z^{-k}}{1 - \sum_{k=1}^{N} a_k z^{-k}}
62  \f}
63  \endhtmlonly
64 
65  \xmlonly
66  H(z) = \ frac{\sum_{k=0}^{M} b_k z^{-k}}{1 - \sum_{k=1}^{N} a_k z^{-k}}
67  \endxmlonly
68 
69  */
70  class FILTER_API iir_filter_ffd : virtual public sync_block
71  {
72  public:
73  // gr::filter::iir_filter_ffd::sptr
75 
76  static sptr make(const std::vector<double> &fftaps,
77  const std::vector<double> &fbtaps,
78  bool oldstyle=true);
79 
80  virtual void set_taps(const std::vector<double> &fftaps,
81  const std::vector<double> &fbtaps) = 0;
82  };
83 
84  } /* namespace filter */
85 } /* namespace gr */
86 
87 #endif /* INCLUDED_IIR_FILTER_FFD_H */
boost::shared_ptr< iir_filter_ffd > sptr
Definition: iir_filter_ffd.h:74
shared_ptr documentation stub
Definition: shared_ptr_docstub.h:15
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:70