GNU Radio 3.6.3 C++ API
mmse_fir_interpolator_ff.h
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1 /* -*- c++ -*- */
2 /*
3  * Copyright 2002,2012 Free Software Foundation, Inc.
4  *
5  * This file is part of GNU Radio
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7  * GNU Radio is free software; you can redistribute it and/or modify
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22 
23 #ifndef _MMSE_FIR_INTERPOLATOR_FF_H_
24 #define _MMSE_FIR_INTERPOLATOR_FF_H_
25 
26 #include <filter/api.h>
27 #include <filter/fir_filter.h>
28 #include <vector>
29 
30 namespace gr {
31  namespace filter {
32 
33  /*!
34  * \brief Compute intermediate samples between signal samples x(k*Ts)
35  * \ingroup filter_primitive
36  *
37  * This implements a Mininum Mean Squared Error interpolator with
38  * 8 taps. It is suitable for signals where the bandwidth of
39  * interest B = 1/(4*Ts) Where Ts is the time between samples.
40  *
41  * Although mu, the fractional delay, is specified as a float, it
42  * is actually quantized. 0.0 <= mu <= 1.0. That is, mu is
43  * quantized in the interpolate method to 32nd's of a sample.
44  *
45  * For more information, in the GNU Radio source code, see:
46  * \li gnuradio-core/src/gen_interpolator_taps/README
47  * \li gnuradio-core/src/gen_interpolator_taps/praxis.txt
48  */
50  {
51  public:
54 
55  unsigned ntaps() const;
56  unsigned nsteps() const;
57 
58  /*!
59  * \brief compute a single interpolated output value.
60  * \p input must have ntaps() valid entries.
61  * input[0] .. input[ntaps() - 1] are referenced to compute the output value.
62  *
63  * \p mu must be in the range [0, 1] and specifies the fractional delay.
64  *
65  * \returns the interpolated input value.
66  */
67  float interpolate(const float input[], float mu) const;
68 
69  protected:
70  std::vector<kernel::fir_filter_fff*> filters;
71  };
72 
73  } /* namespace filter */
74 } /* namespace gr */
75 
76 #endif /* _MMSE_FIR_INTERPOLATOR_FF_H_ */