mayhem-firmware/firmware/baseband/proc_am_audio.cpp

/*
 * 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_am_audio.hpp"

#include "audio_output.hpp"
#include "audio_dma.hpp"

#include "event_m4.hpp"

#include <array>
#include <cmath>
#include "dsp_hilbert.hpp"

// Phase 2: Constructor to start threads AFTER object is fully initialized
NarrowbandAMAudio::NarrowbandAMAudio() {
    // Initialize members that threads might access
    channel_spectrum.set_decimation_factor(1);

    // Start threads AFTER everything initialized
    baseband_thread.start();
    rssi_thread.start();
}

void NarrowbandAMAudio::execute(const buffer_c8_t& buffer) {
    if (!configured) {
        return;
    }

    const auto decim_0_out = decim_0.execute(buffer, dst_buffer);
    const auto audio_decim_0_out = audio_decim_0.execute(decim_0_out, dst_buffer);

    spectrum_samples += decim_0_out.count;
    if (!spectrum_capture_active &&
        spectrum_samples >= spectrum_interval_samples) {
        spectrum_samples -= spectrum_interval_samples;
        spectrum_capture_active =
            channel_spectrum.start_capture(spectrum_decimation_factor);
    }

    if (spectrum_capture_active &&
        channel_spectrum.feed(
            audio_decim_0_out,
            channel_filter_low_f,
            channel_filter_high_f,
            channel_filter_transition)) {
        spectrum_capture_active = false;
    }

    const auto decim_1_out = translating_decim_1.execute(audio_decim_0_out, dst_buffer);
    const auto decim_2_out = decim_2.execute(decim_1_out, dst_buffer);
    const auto channel_out = channel_filter.execute(decim_2_out, dst_buffer);

    // TODO: Feed channel_stats post-decimation data?
    feed_channel_stats(channel_out);

    auto audio = demodulate(channel_out);  // now 3 AM demodulation types : demod_am, demod_ssb, demod_ssb_fm (for Wefax)

    // SDR++-style power squelch on the complex channel signal (opt-in; 0 = off).
    // Measures mean channel power, converts to dBFS, and mutes the audio when
    // the signal is below the user threshold. Carrier-based, so it keys on the
    // AM carrier (e.g. airband/ATC) rather than on audio-band noise.
    if (squelch_level > 0 && channel_out.count > 0) {
        uint64_t sum_mag_sq = 0;
        for (size_t i = 0; i < channel_out.count; i++) {
            const int32_t re = channel_out.p[i].real();
            const int32_t im = channel_out.p[i].imag();
            sum_mag_sq += static_cast<uint64_t>(re) * re + static_cast<uint64_t>(im) * im;
        }

        constexpr float full_scale_mag2 = 32768.0f * 32768.0f;
        const float mean_mag2_norm =
            static_cast<float>(sum_mag_sq) / (static_cast<float>(channel_out.count) * full_scale_mag2);
        const float level_dbfs = (mean_mag2_norm > 0.0f) ? mag2_to_dbv_norm(mean_mag2_norm) : -200.0f;

        // Map squelch_level 1..99 to a threshold of -80..-20 dBFS.
        const float threshold_dbfs = -80.0f + (squelch_level - 1) * (60.0f / 98.0f);
        if (level_dbfs < threshold_dbfs) {
            for (size_t i = 0; i < audio.count; i++)
                audio.p[i] = 0.0f;
        }
    }

    audio_compressor.execute_in_place(audio);
    audio_output.write(audio);
}

buffer_f32_t NarrowbandAMAudio::demodulate(const buffer_c16_t& channel) {
    switch (modulation_ssb) {  // enum class Modulation : int32_t {DSB = 0, SSB = 1, SSB_FM = 2}
        case (int)(AMConfigureMessage::Modulation::DSB):
            return demod_am.execute(channel, audio_buffer);
            break;

        case (int)(AMConfigureMessage::Modulation::SSB):
            return demod_ssb.execute(channel, audio_buffer);
            break;

        case (int)(AMConfigureMessage::Modulation::SSB_FM):  // Added to handle Weather Fax mode.
            // chDbgPanic("case SSB_FM demodulation");                   // Debug.
            return demod_ssb_fm.execute(channel, audio_buffer);  // Calling a derivative of demod_ssb (USB) , but with different FIR taps + FM audio tones demod.
            break;

        // return demod am as a default
        default:
            return demod_am.execute(channel, audio_buffer);
            break;
    }
}

void NarrowbandAMAudio::on_message(const Message* const message) {
    switch (message->id) {
        case Message::ID::UpdateSpectrum:
        case Message::ID::SpectrumStreamingConfig:
            channel_spectrum.on_message(message);
            break;

        case Message::ID::AMConfigure:
            configure(*reinterpret_cast<const AMConfigureMessage*>(message));
            break;

        case Message::ID::CaptureConfig:
            capture_config(*reinterpret_cast<const CaptureConfigMessage*>(message));
            break;

        case Message::ID::AudioDDCConfig:
            ddc_config(*reinterpret_cast<const AudioDDCConfigMessage*>(message));
            break;

        default:
            break;
    }
}

void NarrowbandAMAudio::configure(const AMConfigureMessage& message) {
    constexpr size_t decim_0_input_fs = baseband_fs;
    constexpr size_t decim_0_output_fs = decim_0_input_fs / decim_0.decimation_factor;

    constexpr size_t audio_decim_0_output_fs = decim_0_output_fs / 2;
    constexpr size_t decim_1_output_fs =
        audio_decim_0_output_fs / translating_decim_1.decimation_factor;
    constexpr size_t decim_2_input_fs = decim_1_output_fs;
    constexpr size_t decim_2_output_fs = decim_2_input_fs / decim_2_decimation_factor;

    constexpr size_t channel_filter_input_fs = decim_2_output_fs;
    // const size_t channel_filter_output_fs = channel_filter_input_fs / channel_filter_decimation_factor;

    decim_0.configure(message.decim_0_filter.taps, 33554432);
    audio_decim_0.configure(taps_audio_wide_halfband_0.taps);
    translating_decim_1.configure(
        message.decim_1_filter.taps, audio_decim_0_output_fs);
    decim_2.configure(message.decim_2_filter.taps, decim_2_decimation_factor);
    channel_filter.configure(message.channel_filter.taps, channel_filter_decimation_factor);
    channel_filter_low_f = message.channel_filter.low_frequency_normalized * channel_filter_input_fs;
    channel_filter_high_f = message.channel_filter.high_frequency_normalized * channel_filter_input_fs;
    channel_filter_transition = message.channel_filter.transition_normalized * channel_filter_input_fs;

    modulation_ssb = (int)message.modulation;  // now sending by message , 3 types of AM demod :   enum class Modulation : int32_t {DSB = 0, SSB = 1, SSB_FM = 2}
    spectrum_decimation_factor = 2 * message.channel_spectrum_decimation_factor;
    channel_spectrum.set_decimation_factor(1);
    spectrum_interval_samples =
        decim_0_output_fs / spectrum_rate_hz;
    audio_output.configure(message.audio_hpf_lpf_config);  // hpf in all AM demod modes (AM-6K/9K, USB/LSB,DSB), except Wefax (lpf there).
    squelch_level = message.squelch_level;

    configured = true;
}

void NarrowbandAMAudio::ddc_config(const AudioDDCConfigMessage& message) {
    translating_decim_1.set_frequency(message.frequency);
    channel_spectrum.set_channel_filter_offset(message.frequency);
}

void NarrowbandAMAudio::capture_config(const CaptureConfigMessage& message) {
    if (message.config) {
        audio_output.set_stream(std::make_unique<StreamInput>(message.config));
    } else {
        audio_output.set_stream(nullptr);
    }
}

int main() {
    audio::dma::init_audio_out();

    EventDispatcher event_dispatcher{std::make_unique<NarrowbandAMAudio>()};
    event_dispatcher.run();
    return 0;
}