GNU Radio 3.6.3.1 C++ API
gr_single_pole_iir_filter_cc.h
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1 /* -*- c++ -*- */
2 /*
3  * Copyright 2004,2005,2006 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
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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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14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15  * GNU General Public License for more details.
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21  */
22 
23 #ifndef INCLUDED_GR_SINGLE_POLE_IIR_FILTER_CC_H
24 #define INCLUDED_GR_SINGLE_POLE_IIR_FILTER_CC_H
25 
26 #include <gr_core_api.h>
27 #include <gr_sync_block.h>
28 #include <gr_single_pole_iir.h>
29 #include <gr_complex.h>
30 #include <stdexcept>
31 
34 
36 gr_make_single_pole_iir_filter_cc (double alpha, unsigned int vlen=1);
37 
38 /*!
39  * \brief single pole IIR filter with complex input, complex output
40  * \ingroup filter_blk
41  *
42  * The input and output satisfy a difference equation of the form
43  \htmlonly
44  \f{
45  y[n] - (1-alpha) y[n-1] = alpha x[n]
46  \f}
47  \endhtmlonly
48 
49  \xmlonly
50  y[n] - (1-alpha) y[n-1] = alpha x[n]
51  \endxmlonly
52 
53  * with the corresponding rational system function
54  \htmlonly
55  \f{
56  H(z) = \frac{alpha}{1 - (1-alpha) z^{-1}}
57  \f}
58  \endhtmlonly
59 
60  \xmlonly
61  H(z) = \ frac{alpha}{1 - (1-alpha) z^{-1}}
62  \endxmlonly
63 
64  * Note that some texts define the system function with a + in the denominator.
65  * If you're using that convention, you'll need to negate the feedback tap.
66  */
68 {
69  private:
71  gr_make_single_pole_iir_filter_cc (double alpha, unsigned int vlen);
72 
73  unsigned int d_vlen;
74  std::vector<gr_single_pole_iir<gr_complex,gr_complex,double> > d_iir;
75 
76  gr_single_pole_iir_filter_cc (double alpha, unsigned int vlen);
77 
78  public:
80 
81  void set_taps (double alpha);
82 
83  int work (int noutput_items,
84  gr_vector_const_void_star &input_items,
85  gr_vector_void_star &output_items);
86 };
87 
88 #endif