GNU Radio C++ API Reference: cpm.h Source File

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cpm.h
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1/* -*- c++ -*- */
2/*
3 * Copyright 2010,2012 Free Software Foundation, Inc.
4 *
5 * SPDX-License-Identifier: GPL-3.0-or-later
6 *
7 */
8
9
10#ifndef INCLUDED_ANALOG_CPM_H
11#define INCLUDED_ANALOG_CPM_H
12
13#include <gnuradio/analog/api.h>
14#include <vector>
15
16namespace gr {
17namespace analog {
18
19/*! \brief Return the taps for an interpolating FIR filter
20 * (gr::filter::interp_fir_filter_fff).
21 */
22 class ANALOG_API cpm
23{
24public:
25 enum cpm_type { LRC, LSRC, LREC, TFM, GAUSSIAN, GENERIC = 999 };
26
27 /*! \brief Return the taps for an interpolating FIR filter
28 * (gr::filter::interp_fir_filter_fff).
29 *
30 * \details
31 * These taps represent the phase response \f$g(k)\f$ for use in a CPM modulator,
32 * see also gr_cpmmod_bc.
33 *
34 * \param type The CPM type (Rectangular, Raised Cosine,
35 * Spectral Raised Cosine, Tamed FM or Gaussian).
36 * \param samples_per_sym Samples per symbol.
37 * \param L The length of the phase response in symbols.
38 * \param beta For Spectral Raised Cosine, this is the rolloff
39 * factor. For Gaussian phase responses, this the
40 * 3dB-time-bandwidth product. For all other cases,
41 * it is ignored.
42 *
43 * Output: returns a vector of length \a K = \p samples_per_sym
44 * x \p L. This can be used directly in an
45 * interpolating FIR filter such as
46 * gr_interp_fir_filter_fff with interpolation factor \p
47 * samples_per_sym.
48 *
49 * All phase responses are normalised s.t. \f$ \sum_{k=0}^{K-1}
50 * g(k) = 1\f$; this will cause a maximum phase change of \f$ h
51 * \cdot \pi\f$ between two symbols, where \a h is the
52 * modulation index.
53 *
54 * The following phase responses can be generated:
55 * - LREC: Rectangular phase response.
56 * - LRC: Raised cosine phase response, looks like 1 - cos(x).
57 * - LSRC: Spectral raised cosine. This requires a rolloff factor beta.
58 * The phase response is the Fourier transform of raised cosine
59 * function.
60 * - TFM: Tamed frequency modulation. This scheme minimizes phase change for
61 * rapidly varying input symbols.
62 * - GAUSSIAN: A Gaussian phase response. For a modulation index h = 1/2, this
63 * results in GMSK.
64 *
65 * A short description of all these phase responses can be found in [1].
66 *
67 * [1]: Anderson, Aulin and Sundberg; Digital Phase Modulation
68 */
69 static std::vector<float> phase_response(cpm_type type,
70 unsigned samples_per_sym,
71 unsigned L,
72 double beta = 0.3);
73};
74} // namespace analog
75} // namespace gr
76
77#endif /* INCLUDED_ANALOG_CPM_H */
gr::analog::cpm
Return the taps for an interpolating FIR filter (gr::filter::interp_fir_filter_fff).
Definition cpm.h:23
gr::analog::cpm::phase_response
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).
gr::analog::cpm::cpm_type
cpm_type
Definition cpm.h:25
gr::analog::cpm::TFM
@ TFM
Definition cpm.h:25
gr::analog::cpm::LREC
@ LREC
Definition cpm.h:25
gr::analog::cpm::GENERIC
@ GENERIC
Definition cpm.h:25
gr::analog::cpm::LRC
@ LRC
Definition cpm.h:25
gr::analog::cpm::LSRC
@ LSRC
Definition cpm.h:25
gr::analog::cpm::GAUSSIAN
@ GAUSSIAN
Definition cpm.h:25
api.h
ANALOG_API
#define ANALOG_API
Definition gr-analog/include/gnuradio/analog/api.h:18
gr::analog
Definition agc.h:19
gr
GNU Radio logging wrapper.
Definition basic_block.h:29