2015-08-27 16:19:34 -04:00
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/*
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* Copyright (C) 2014 Jared Boone, ShareBrained Technology, Inc.
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*
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* This file is part of PortaPack.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2, or (at your option)
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* any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; see the file COPYING. If not, write to
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* the Free Software Foundation, Inc., 51 Franklin Street,
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* Boston, MA 02110-1301, USA.
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*/
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#include "proc_wfm_audio.hpp"
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#include <cstdint>
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2015-12-10 15:36:12 -05:00
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void WidebandFMAudio::execute(const buffer_c8_t& buffer) {
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2015-08-27 16:19:34 -04:00
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auto decimator_out = decimator.execute(buffer);
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const buffer_s16_t work_audio_buffer {
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(int16_t*)decimator_out.p,
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sizeof(*decimator_out.p) * decimator_out.count
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};
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auto channel = decimator_out;
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// TODO: Feed channel_stats post-decimation data?
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feed_channel_stats(channel);
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//feed_channel_spectrum(channel);
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/* 768kHz complex<int16_t>[512]
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* -> FM demodulation
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* -> 768kHz int16_t[512] */
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/* TODO: To improve adjacent channel rejection, implement complex channel filter:
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* pass < +/- 100kHz, stop > +/- 200kHz
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*/
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auto audio_oversampled = demod.execute(decimator_out, work_audio_buffer);
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/* 768kHz int16_t[512]
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* -> 4th order CIC decimation by 2, gain of 1
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* -> 384kHz int16_t[256] */
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auto audio_8fs = audio_dec_1.execute(audio_oversampled, work_audio_buffer);
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/* 384kHz int16_t[256]
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* -> 4th order CIC decimation by 2, gain of 1
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* -> 192kHz int16_t[128] */
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auto audio_4fs = audio_dec_2.execute(audio_8fs, work_audio_buffer);
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/* 192kHz int16_t[128]
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* -> 4th order CIC decimation by 2, gain of 1
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* -> 96kHz int16_t[64] */
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auto audio_2fs = audio_dec_3.execute(audio_4fs, work_audio_buffer);
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/* 96kHz int16_t[64]
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* -> FIR filter, <15kHz (0.156fs) pass, >19kHz (0.198fs) stop, gain of 1
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* -> 48kHz int16_t[32] */
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auto audio = audio_filter.execute(audio_2fs, work_audio_buffer);
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/* -> 48kHz int16_t[32] */
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audio_hpf.execute_in_place(audio);
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fill_audio_buffer(audio);
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}
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