GNU Radio 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
8  * it under the terms of the GNU General Public License as published by
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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.
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17  * You should have received a copy of the GNU General Public License
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19  * the Free Software Foundation, Inc., 51 Franklin Street,
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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 
44  \f[
45  y[n] - (1-alpha) y[n-1] = alpha x[n]
46  \f]
47 
48  * with the corresponding rational system function
49 
50  \f[
51  H(z) = \frac{alpha}{1 - (1-alpha) z^{-1}}
52  \f]
53 
54  * Note that some texts define the system function with a + in the denominator.
55  * If you're using that convention, you'll need to negate the feedback tap.
56  */
58 {
59  private:
61  gr_make_single_pole_iir_filter_cc (double alpha, unsigned int vlen);
62 
63  unsigned int d_vlen;
64  std::vector<gr_single_pole_iir<gr_complex,gr_complex,double> > d_iir;
65 
66  gr_single_pole_iir_filter_cc (double alpha, unsigned int vlen);
67 
68  public:
70 
71  void set_taps (double alpha);
72 
73  int work (int noutput_items,
74  gr_vector_const_void_star &input_items,
75  gr_vector_void_star &output_items);
76 };
77 
78 #endif