GNU Radio C++ API
gr_single_pole_iir_filter_ff.h
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1 /* -*- c++ -*- */
2 /*
3  * Copyright 2004,2005 Free Software Foundation, Inc.
4  *
5  * This file is part of GNU Radio
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22 
23 #ifndef INCLUDED_GR_SINGLE_POLE_IIR_FILTER_FF_H
24 #define INCLUDED_GR_SINGLE_POLE_IIR_FILTER_FF_H
25 
26 #include <gr_core_api.h>
27 #include <gr_sync_block.h>
28 #include <gr_single_pole_iir.h>
29 #include <stdexcept>
30 
33 
35 gr_make_single_pole_iir_filter_ff (double alpha, unsigned int vlen=1);
36 
37 /*!
38  * \brief single pole IIR filter with float input, float output
39  * \ingroup filter_blk
40  *
41  * The input and output satisfy a difference equation of the form
42 
43  \f[
44  y[n] - (1-alpha) y[n-1] = alpha x[n]
45  \f]
46 
47  * with the corresponding rational system function
48 
49  \f[
50  H(z) = \frac{alpha}{1 - (1-alpha) z^{-1}}
51  \f]
52 
53  * Note that some texts define the system function with a + in the denominator.
54  * If you're using that convention, you'll need to negate the feedback tap.
55  */
57 {
58  private:
60  gr_make_single_pole_iir_filter_ff (double alpha, unsigned int vlen);
61 
62  unsigned int d_vlen;
63  std::vector<gr_single_pole_iir<float,float,double> > d_iir;
64 
65  gr_single_pole_iir_filter_ff (double alpha, unsigned int vlen);
66 
67  public:
69 
70  void set_taps (double alpha);
71 
72  int work (int noutput_items,
73  gr_vector_const_void_star &input_items,
74  gr_vector_void_star &output_items);
75 };
76 
77 #endif