GNU Radio 3.6.2 C++ API
single_pole_iir_filter_cc.h
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1 /* -*- c++ -*- */
2 /*
3  * Copyright 2004-2006,2012 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
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10  * any later version.
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12  * GNU Radio is distributed in the hope that it will be useful,
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15  * GNU General Public License for more details.
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17  * You should have received a copy of the GNU General Public License
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21  */
22 
23 #ifndef INCLUDED_SINGLE_POLE_IIR_FILTER_CC_H
24 #define INCLUDED_SINGLE_POLE_IIR_FILTER_CC_H
25 
26 #include <filter/api.h>
27 #include <filter/single_pole_iir.h>
28 #include <gr_sync_block.h>
29 #include <gr_complex.h>
30 
31 namespace gr {
32  namespace filter {
33 
34  /*!
35  * \brief single pole IIR filter with complex input, complex output
36  * \ingroup filter_blk
37  *
38  * The input and output satisfy a difference equation of the form
39  \htmlonly
40  \f{
41  y[n] - (1-alpha) y[n-1] = alpha x[n]
42  \f}
43  \endhtmlonly
44 
45  \xmlonly
46  y[n] - (1-alpha) y[n-1] = alpha x[n]
47  \endxmlonly
48 
49  * with the corresponding rational system function
50  \htmlonly
51  \f{
52  H(z) = \frac{alpha}{1 - (1-alpha) z^{-1}}
53  \f}
54  \endhtmlonly
55 
56  \xmlonly
57  H(z) = \ frac{alpha}{1 - (1-alpha) z^{-1}}
58  \endxmlonly
59 
60  * Note that some texts define the system function with a + in the
61  * denominator. If you're using that convention, you'll need to
62  * negate the feedback tap.
63  */
65  {
66  public:
67  // gr::filter::single_pole_iir_filter_cc::sptr
69 
70  static sptr make(double alpha, unsigned int vlen=1);
71 
72  virtual void set_taps(double alpha) = 0;
73  };
74 
75  } /* namespace filter */
76 } /* namespace gr */
77 
78 #endif /* INCLUDED_SINGLE_POLE_IIR_FILTER_CC_H */