portapack-mayhem/firmware/baseband/proc_nfm_audio.cpp
Jared Boone 7de80edcd3 Move baseband FIR filter defs to common file.
They will likely be shared with multiple decimators/demodulators.
Also added normalized filter pass/stop values to each set of taps.
2015-12-30 12:19:42 -08:00

118 lines
4.3 KiB
C++

/*
* Copyright (C) 2014 Jared Boone, ShareBrained Technology, Inc.
*
* This file is part of PortaPack.
*
* This program 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 2, or (at your option)
* any later version.
*
* This program 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 this program; see the file COPYING. If not, write to
* the Free Software Foundation, Inc., 51 Franklin Street,
* Boston, MA 02110-1301, USA.
*/
#include "proc_nfm_audio.hpp"
#include <cstdint>
#include <cstddef>
NarrowbandFMAudio::NarrowbandFMAudio() {
set_mode(Mode::Deviation2K5Narrow);
}
void NarrowbandFMAudio::set_mode(const Mode mode) {
constexpr size_t baseband_fs = 3072000;
constexpr size_t decim_0_input_fs = baseband_fs;
constexpr size_t decim_0_decimation_factor = 8;
constexpr size_t decim_0_output_fs = decim_0_input_fs / decim_0_decimation_factor;
constexpr size_t decim_1_input_fs = decim_0_output_fs;
constexpr size_t decim_1_decimation_factor = 8;
constexpr size_t decim_1_output_fs = decim_1_input_fs / decim_1_decimation_factor;
constexpr size_t channel_filter_input_fs = decim_1_output_fs;
constexpr size_t channel_filter_decimation_factor = 1;
constexpr size_t channel_filter_output_fs = channel_filter_input_fs / channel_filter_decimation_factor;
constexpr size_t demod_input_fs = channel_filter_output_fs;
switch(mode) {
default:
case Mode::Deviation5K:
decim_0.configure(taps_16k0_decim_0.taps, 33554432);
decim_1.configure(taps_16k0_decim_1.taps, 131072);
channel_filter.configure(taps_16k0_channel.taps, channel_filter_decimation_factor);
demod.configure(demod_input_fs, 5000);
channel_filter_pass_f = taps_16k0_channel.pass_frequency_normalized * channel_filter_input_fs;
channel_filter_stop_f = taps_16k0_channel.stop_frequency_normalized * channel_filter_input_fs;
break;
case Mode::Deviation2K5Wide:
decim_0.configure(taps_11k0_decim_0.taps, 33554432);
decim_1.configure(taps_11k0_decim_1.taps, 131072);
channel_filter.configure(taps_11k0_channel.taps, channel_filter_decimation_factor);
demod.configure(demod_input_fs, 2500);
channel_filter_pass_f = taps_11k0_channel.pass_frequency_normalized * channel_filter_input_fs;
channel_filter_stop_f = taps_11k0_channel.stop_frequency_normalized * channel_filter_input_fs;
break;
case Mode::Deviation2K5Narrow:
decim_0.configure(taps_4k25_decim_0.taps, 33554432);
decim_1.configure(taps_4k25_decim_1.taps, 131072);
channel_filter.configure(taps_4k25_channel.taps, channel_filter_decimation_factor);
demod.configure(demod_input_fs, 2500);
channel_filter_pass_f = taps_4k25_channel.pass_frequency_normalized * channel_filter_input_fs;
channel_filter_stop_f = taps_4k25_channel.stop_frequency_normalized * channel_filter_input_fs;
break;
}
channel_spectrum.set_decimation_factor(std::floor((channel_filter_output_fs / 2) / ((channel_filter_pass_f + channel_filter_stop_f) / 2)));
}
void NarrowbandFMAudio::execute(const buffer_c8_t& buffer) {
const buffer_c16_t dst_buffer {
dst.data(),
dst.size()
};
const auto decim_0_out = decim_0.execute(buffer, dst_buffer);
const auto decim_1_out = decim_1.execute(decim_0_out, dst_buffer);
const auto channel_out = channel_filter.execute(decim_1_out, dst_buffer);
feed_channel_stats(channel_out);
channel_spectrum.feed(channel_out, channel_filter_pass_f, channel_filter_stop_f);
const buffer_s16_t work_audio_buffer {
(int16_t*)dst.data(),
sizeof(*dst.data()) * dst.size()
};
auto audio = demod.execute(channel_out, work_audio_buffer);
static uint64_t audio_present_history = 0;
const auto audio_present_now = squelch.execute(audio);
audio_present_history = (audio_present_history << 1) | (audio_present_now ? 1 : 0);
const bool audio_present = (audio_present_history != 0);
audio_hpf.execute_in_place(audio);
audio_deemph.execute_in_place(audio);
if( !audio_present ) {
// Zero audio buffer.
for(size_t i=0; i<audio.count; i++) {
audio.p[i] = 0;
}
}
fill_audio_buffer(audio);
}