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/* -*- c++ -*- */
/*
* Gqrx SDR: Software defined radio receiver powered by GNU Radio and Qt
* http://gqrx.dk/
*
* Copyright 2012 Alexandru Csete OZ9AEC.
* FM stereo implementation by Alex Grinkov a.grinkov(at)gmail.com.
*
* 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.
*/
#include <gnuradio/io_signature.h>
#include <math.h>
#include <iostream>
#include <dsp/stereo_demod.h>
/* Create a new instance of stereo_demod and return a boost shared_ptr. */
stereo_demod_sptr make_stereo_demod(float quad_rate, float audio_rate,
bool stereo, bool oirt)
{
return gnuradio::get_initial_sptr(new stereo_demod(quad_rate,
audio_rate, stereo, oirt));
}
static const int MIN_IN = 1; /* Mininum number of input streams. */
static const int MAX_IN = 1; /* Maximum number of input streams. */
static const int MIN_OUT = 2; /* Minimum number of output streams. */
static const int MAX_OUT = 2; /* Maximum number of output streams. */
#define STEREO_DEMOD_PARANOIC
/*! \brief Create stereo demodulator object.
*
* Use make_stereo_demod() instead.
*/
stereo_demod::stereo_demod(float input_rate, float audio_rate, bool stereo, bool oirt)
: gr::hier_block2("stereo_demod",
gr::io_signature::make (MIN_IN, MAX_IN, sizeof (float)),
gr::io_signature::make (MIN_OUT, MAX_OUT, sizeof (float))),
d_input_rate(input_rate),
d_audio_rate(audio_rate),
d_stereo(stereo),
d_oirt(oirt)
{
double cutof_freq = d_oirt ? 15e3 : 17e3;
lpf0 = make_lpf_ff(d_input_rate, cutof_freq, 2e3); // FIXME
audio_rr0 = make_resampler_ff(d_audio_rate/d_input_rate);
if (d_stereo)
{
lpf1 = make_lpf_ff(d_input_rate, cutof_freq, 2e3); // FIXME
audio_rr1 = make_resampler_ff(d_audio_rate/d_input_rate);
if (!d_oirt)
{
d_tone_taps = gr::filter::firdes::complex_band_pass(
1.0, // gain,
d_input_rate, // sampling_freq
18800., // low_cutoff_freq
19200., // high_cutoff_freq
300.); // transition_width
pll = gr::analog::pll_refout_cc::make(0.001, // loop_bw FIXME
2*M_PI * 19200 / input_rate, // max_freq
2*M_PI * 18800 / input_rate); // min_freq
subtone = gr::blocks::multiply_cc::make();
} else {
d_tone_taps = gr::filter::firdes::complex_band_pass(
1.0, // gain,
d_input_rate, // sampling_freq
31200., // low_cutoff_freq
31300., // high_cutoff_freq
100.); // transition_width
pll = gr::analog::pll_refout_cc::make(0.001, // loop_bw FIXME
2*M_PI * 31200 / input_rate, // max_freq
2*M_PI * 31300 / input_rate); // min_freq
}
tone = gr::filter::fir_filter_fcc::make(1, d_tone_taps);
lo = gr::blocks::complex_to_imag::make();
#ifdef STEREO_DEMOD_PARANOIC
d_pll_taps = gr::filter::firdes::band_pass(
1.0, // gain,
d_input_rate, // sampling_freq
37600., // low_cutoff_freq
38400., // high_cutoff_freq
400.); // transition_width
lo2 = gr::filter::fir_filter_fff::make(1, d_pll_taps);
#endif
mixer = gr::blocks::multiply_ff::make();
cdp = gr::blocks::multiply_const_ff::make( 5.5); // FIXME
cdm = gr::blocks::multiply_const_ff::make(-5.5); // FIXME
add0 = gr::blocks::add_ff::make();
add1 = gr::blocks::add_ff::make();
/* connect block */
if (!d_oirt) {
connect(self(), 0, tone, 0);
connect(tone, 0, pll, 0);
connect(pll, 0, subtone, 0);
connect(pll, 0, subtone, 1);
connect(subtone, 0, lo, 0);
#ifdef STEREO_DEMOD_PARANOIC
connect(lo, 0, lo2, 0);
connect(lo2, 0, mixer, 0);
#else
connect(lo, 0, mixer, 0);
#endif
} else {
connect(self(), 0, tone, 0);
connect(tone, 0, pll, 0);
connect(pll, 0, lo, 0);
connect(lo, 0, mixer, 0);
}
connect(self(), 0, mixer, 1);
connect(self(), 0, lpf0, 0);
connect(mixer, 0, lpf1, 0);
connect(lpf0, 0, audio_rr0, 0); // sum
connect(lpf1, 0, audio_rr1, 0);
connect(audio_rr1, 0, cdp, 0); // +delta
connect(audio_rr1, 0, cdm, 0); // -delta
connect(audio_rr0, 0, add0, 0);
connect(cdp, 0, add0, 1);
connect(add0, 0, self(), 0); // left = sum + delta
connect(audio_rr0, 0, add1, 0);
connect(cdm, 0, add1, 1);
connect(add1, 0, self(), 1); // right = sum + delta
}
else // if (!d_stereo)
{
/* connect block */
connect(self(), 0, lpf0, 0);
connect(lpf0, 0, audio_rr0, 0);
connect(audio_rr0, 0, self(), 0);
connect(audio_rr0, 0, self(), 1);
}
}
stereo_demod::~stereo_demod()
{
}
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