GNU Radio 3.6.5.1 C++ API
digital_cpmmod_bc.h
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1 /* -*- c++ -*- */
2 /*
3  * Copyright 2010 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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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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18  * along with GNU Radio; see the file COPYING. If not, write to
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21  */
22 
23 #ifndef INCLUDED_DIGITAL_CPMMOD_BC_H
24 #define INCLUDED_DIGITAL_CPMMOD_BC_H
25 
26 #include <digital_api.h>
27 #include <gr_hier_block2.h>
28 #include <gr_char_to_float.h>
29 #include <gr_interp_fir_filter_fff.h>
31 #include <gr_cpm.h>
32 
33 
34 class digital_cpmmod_bc;
36 
37 
39 digital_make_cpmmod_bc(int type, float h,
40  unsigned samples_per_sym,
41  unsigned L, double beta=0.3);
42 
43 /*!
44  * \brief Generic CPM modulator
45  * \ingroup modulators_blk
46  *
47  * \details
48  * Examples:
49  * - Setting h = 0.5, L = 1, type = LREC yields MSK.
50  * - Setting h = 0.5, type = GAUSSIAN and beta = 0.3 yields GMSK
51  * as used in GSM.
52  *
53  * The input of this block are symbols from an M-ary alphabet
54  * +/-1, +/-3, ..., +/-(M-1). Usually, M = 2 and therefore, the
55  * valid inputs are +/-1.
56  * The modulator will silently accept any other inputs, though.
57  * The output is the phase-modulated signal.
58  */
60 {
62  digital_make_cpmmod_bc(int type, float h,
63  unsigned samples_per_sym,
64  unsigned L, double beta);
65 
66  std::vector<float> d_taps;
67  gr_char_to_float_sptr d_char_to_float;
68  gr_interp_fir_filter_fff_sptr d_pulse_shaper;
70 
71 protected:
72  /*!
73  * Build a generic CPM modulator block.
74  *
75  * \param type The modulation type. Can be one of LREC, LRC, LSRC, TFM
76  * or GAUSSIAN. See gr_cpm::phase_response() for a
77  * detailed description.
78  * \param h The modulation index. \f$ h \cdot \pi\f$ is the maximum
79  * phase change that can occur between two symbols, i.e., if
80  * you only send ones, the phase will increase by \f$ h \cdot
81  * \pi\f$ every \p samples_per_sym samples. Set this to 0.5
82  * for Minimum Shift Keying variants.
83  * \param samples_per_sym Samples per symbol.
84  * \param L The length of the phase duration in symbols. For L=1, this
85  * yields full- response CPM symbols, for L > 1,
86  * partial-response.
87  * \param beta For LSRC, this is the rolloff factor. For Gaussian
88  * pulses, this is the 3 dB time-bandwidth product.
89  */
90  digital_cpmmod_bc(gr_cpm::cpm_type type, float h,
91  unsigned samples_per_sym,
92  unsigned L, double beta);
93 
94 public:
95  //! Return the phase response FIR taps
96  std::vector<float> get_taps() { return d_taps; };
97 };
98 
99 #endif /* INCLUDED_DIGITAL_CPMMOD_BC_H */
100