1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
|
/* -*- c++ -*- */
/*
* Gqrx SDR: Software defined radio receiver powered by GNU Radio and Qt
* http://gqrx.dk/
*
* Copyright 2011 Alexandru Csete OZ9AEC.
*
* Gqrx is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 3, or (at your option)
* any later version.
*
* Gqrx is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with Gqrx; see the file COPYING. If not, write to
* the Free Software Foundation, Inc., 51 Franklin Street,
* Boston, MA 02110-1301, USA.
*/
#ifndef RX_DEMOD_FM_H
#define RX_DEMOD_FM_H
#include <gnuradio/hier_block2.h>
#include <gnuradio/analog/quadrature_demod_cf.h>
#include <gnuradio/filter/iir_filter_ffd.h>
#include <gnuradio/filter/pfb_arb_resampler_ccf.h>
#include <vector>
class rx_demod_fm;
typedef boost::shared_ptr<rx_demod_fm> rx_demod_fm_sptr;
/*! \brief Return a shared_ptr to a new instance of rx_demod_fm.
* \param quad_rate The input sample rate.
* \param audio_rate The audio rate.
* \param max_dev Maximum deviation in Hz
* \param tau De-emphasis time constant in seconds (75us in US, 50us in EUR, 0.0 disables).
*
* This is effectively the public constructor. To avoid accidental use
* of raw pointers, rx_demod_fm's constructor is private.
* make_rx_dmod_fm is the public interface for creating new instances.
*/
rx_demod_fm_sptr make_rx_demod_fm(float quad_rate, float audio_rate, float max_dev=5000.0, double tau=50.0e-6);
/*! \brief FM demodulator.
* \ingroup DSP
*
* This class implements the FM demodulator using the gr_quadrature_demod block.
* It also provides de-emphasis with variable time constant (use 0.0 to disable).
*
*/
class rx_demod_fm : public gr::hier_block2
{
public:
rx_demod_fm(float quad_rate=48000.0, float audio_rate=48000.0, float max_dev=5000.0, double tau=50.0e-6); // FIXME: should be private
~rx_demod_fm();
void set_max_dev(float max_dev);
void set_tau(double tau);
private:
/* GR blocks */
gr::analog::quadrature_demod_cf::sptr d_quad; /*! The quadrature demodulator block. */
gr::filter::iir_filter_ffd::sptr d_deemph; /*! De-emphasis IIR filter. */
gr::filter::pfb_arb_resampler_ccf::sptr d_resampler; /*! PFB resampler. */
std::vector<float> d_taps; /*! Taps for the PFB resampler. */
/* other parameters */
float d_quad_rate; /*! Quadrature rate. */
float d_audio_rate; /*! Audio rate. */
float d_max_dev; /*! Max deviation. */
double d_tau; /*! De-emphasis time constant. */
/* De-emph IIR filter taps */
std::vector<double> d_fftaps; /*! Feed forward taps. */
std::vector<double> d_fbtaps; /*! Feed back taps. */
void calculate_iir_taps(double tau);
};
#endif // RX_DEMOD_FM_H
|
