GNU Radio Manual and C++ API Reference 3.7.14.0
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cpm.h
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1/* -*- c++ -*- */
2/*
3 * Copyright 2010,2012 Free Software Foundation, Inc.
4 *
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20
21
22#ifndef INCLUDED_ANALOG_CPM_H
23#define INCLUDED_ANALOG_CPM_H
24
25#include <gnuradio/analog/api.h>
26#include <vector>
27
28namespace gr {
29namespace analog {
30
31/*! \brief Return the taps for an interpolating FIR filter
32 * (gr::filter::interp_fir_filter_fff).
33 */
35{
36public:
37 enum cpm_type { LRC, LSRC, LREC, TFM, GAUSSIAN, GENERIC = 999 };
38
39 /*! \brief Return the taps for an interpolating FIR filter
40 * (gr::filter::interp_fir_filter_fff).
41 *
42 * \details
43 * These taps represent the phase response \f$g(k)\f$ for use in a CPM modulator,
44 * see also gr_cpmmod_bc.
45 *
46 * \param type The CPM type (Rectangular, Raised Cosine,
47 * Spectral Raised Cosine, Tamed FM or Gaussian).
48 * \param samples_per_sym Samples per symbol.
49 * \param L The length of the phase response in symbols.
50 * \param beta For Spectral Raised Cosine, this is the rolloff
51 * factor. For Gaussian phase responses, this the
52 * 3dB-time-bandwidth product. For all other cases,
53 * it is ignored.
54 *
55 * Output: returns a vector of length \a K = \p samples_per_sym
56 * x \p L. This can be used directly in an
57 * interpolating FIR filter such as
58 * gr_interp_fir_filter_fff with interpolation factor \p
59 * samples_per_sym.
60 *
61 * All phase responses are normalised s.t. \f$ \sum_{k=0}^{K-1}
62 * g(k) = 1\f$; this will cause a maximum phase change of \f$ h
63 * \cdot \pi\f$ between two symbols, where \a h is the
64 * modulation index.
65 *
66 * The following phase responses can be generated:
67 * - LREC: Rectangular phase response.
68 * - LRC: Raised cosine phase response, looks like 1 - cos(x).
69 * - LSRC: Spectral raised cosine. This requires a rolloff factor beta.
70 * The phase response is the Fourier transform of raised cosine
71 * function.
72 * - TFM: Tamed frequency modulation. This scheme minimizes phase change for
73 * rapidly varying input symbols.
74 * - GAUSSIAN: A Gaussian phase response. For a modulation index h = 1/2, this
75 * results in GMSK.
76 *
77 * A short description of all these phase responses can be found in [1].
78 *
79 * [1]: Anderson, Aulin and Sundberg; Digital Phase Modulation
80 */
81 static std::vector<float> phase_response(cpm_type type,
82 unsigned samples_per_sym,
83 unsigned L,
84 double beta = 0.3);
85};
86} // namespace analog
87} // namespace gr
88
89#endif /* INCLUDED_ANALOG_CPM_H */
Return the taps for an interpolating FIR filter (gr::filter::interp_fir_filter_fff).
Definition: cpm.h:35
static std::vector< float > phase_response(cpm_type type, unsigned samples_per_sym, unsigned L, double beta=0.3)
Return the taps for an interpolating FIR filter (gr::filter::interp_fir_filter_fff).
cpm_type
Definition: cpm.h:37
#define ANALOG_API
Definition: gr-analog/include/gnuradio/analog/api.h:30
Include this header to use the message passing features.
Definition: basic_block.h:45