Noaa apt decoder (#2648)

firmware/baseband/CMakeLists.txt

@@ -676,6 +676,14 @@ set(MODE_CPPSRC
 DeclareTargets(PWFX wefaxrx)
 
 
+### NoaaApt Rx
+
+set(MODE_CPPSRC
+	proc_noaaapt_rx.cpp
+)
+DeclareTargets(PNOA noaaapt_rx)
+
+
 ### HackRF "factory" firmware
 
 add_custom_command(

firmware/baseband/audio_output.cpp

@@ -65,6 +65,18 @@ void AudioOutput::apt_write(const buffer_s16_t& audio) {
     write(buffer_f32_t{audio_f.data(), audio.count, audio.sampling_rate});
 }
 
+void AudioOutput::apt_write(const buffer_s16_t& audio, std::array<float, 32>& audio_f) {
+    for (size_t i = 0; i < audio.count; i++) {
+        cur = audio.p[i];
+        cur2 = cur * cur;
+        mag_am = sqrtf(prev2 + cur2 - (2 * prev * cur * cos_theta)) / sin_theta;
+        audio_f[i] = mag_am * ki;  // normalize.
+        prev = cur;
+        prev2 = cur2;
+    }
+    write(buffer_f32_t{audio_f.data(), audio.count, audio.sampling_rate});
+}
+
 void AudioOutput::write(const buffer_s16_t& audio) {
     std::array<float, 32> audio_f;
     for (size_t i = 0; i < audio.count; i++) {

firmware/baseband/audio_output.hpp

@@ -47,6 +47,7 @@ class AudioOutput {
 
     void write_unprocessed(const buffer_s16_t& audio);
     void apt_write(const buffer_s16_t& audio);
+    void apt_write(const buffer_s16_t& audio, std::array<float, 32>& audio_f);
     void write(const buffer_s16_t& audio);
     void write(const buffer_f32_t& audio);
 

firmware/baseband/proc_noaaapt_rx.cpp

@@ -0,0 +1,180 @@
+/*
+ * Copyright (C) 2025 Brumi, HTotoo
+ *
+ * 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_noaaapt_rx.hpp"
+#include "sine_table_int8.hpp"
+#include "portapack_shared_memory.hpp"
+
+#include "audio_dma.hpp"
+#include "math.h"
+#include "event_m4.hpp"
+#include "fxpt_atan2.hpp"
+
+#include <cstdint>
+#include <cstddef>
+
+#define NOAAAPT_PX_SIZE 2080.0
+
+// updates the per pixel timers
+void NoaaAptRx::update_params() {
+    // TODO HTOTOO
+    //  2080 px / line with chan a,b + sync + telemetry
+    pxRem = (double)12000.0 / NOAAAPT_PX_SIZE / 2.0;
+    samples_per_pixel = pxRem;
+    pxRem -= samples_per_pixel;
+    pxRoll = 0;
+    status_message.state = 0;
+    shared_memory.application_queue.push(status_message);
+}
+
+void NoaaAptRx::execute(const buffer_c8_t& buffer) {
+    if (!configured) {
+        return;
+    }
+    const auto decim_0_out = decim_0.execute(buffer, dst_buffer);
+    const auto channel = decim_1.execute(decim_0_out, dst_buffer);
+    // TODO: Feed channel_stats post-decimation data?
+    feed_channel_stats(channel);
+
+    /* spectrum_samples += channel.count;
+    if (spectrum_samples >= spectrum_interval_samples) {
+        spectrum_samples -= spectrum_interval_samples;
+        channel_spectrum.feed(channel, channel_filter_low_f, channel_filter_high_f, channel_filter_transition);
+    }
+    */
+    /* 96kHz complex<int16_t>[64]  for wfmam NOAA
+     * -> FM demodulation
+     * -> 96kHz int16_t[64] */
+    auto audio_oversampled = demod.execute(channel, work_audio_buffer);  // fs 384khz wfm , 96khz wfmam for NOAA
+    /* 96kHz int16_t[64]     for wfam
+     * -> 4th order CIC decimation by 2, gain of 1
+     * -> 48kHz int16_t[32] */
+    auto audio_4fs = audio_dec_1.execute(audio_oversampled, work_audio_buffer);
+    /* 48kHz int16_t[32]     for wfman
+     * -> 4th order CIC decimation by 2, gain of 1
+     * -> 24kHz int16_t[16] */
+    auto audio_2fs = audio_dec_2.execute(audio_4fs, work_audio_buffer);
+    /* 24kHz int16_t[16]          for wfmam
+     * -> FIR filter, <4.5kHz (0.1875fs) pass, >5.2kHz (0.2166fs) stop, gain of 1
+     * -> 12kHz int16_t[8] */
+    auto audio = audio_filter.execute(audio_2fs, work_audio_buffer);
+    /* -> 12kHz int16_t[8]   for wfmam ,  */
+    std::array<float, 32> audio_f;
+    audio_output.apt_write(audio, audio_f);  // we are in added wfmam (noaa), decim_1.decimation_factor == 8
+
+    for (size_t c = 0; c < audio.count; c++) {
+        if (status_message.state == 0 && false) {  // disabled this due to NIY
+            // first look for the sync!
+
+        } else {
+            cnt++;
+            if (cnt >= (samples_per_pixel + (uint32_t)pxRoll)) {  // got a pixel
+                cnt = 0;
+                if (pxRoll >= 1) pxRoll -= 1.0;
+                pxRoll += pxRem;
+
+                if (image_message.cnt < 400) {
+                    if (audio_f[c] >= 1) {
+                        image_message.image[image_message.cnt++] = 255;
+                    } else if (audio_f[c] <= 0) {
+                        image_message.image[image_message.cnt++] = 0;
+                    } else {
+                        image_message.image[image_message.cnt++] = (audio_f[c]) * 255;
+                    }
+                }
+                if (image_message.cnt >= 399) {
+                    shared_memory.application_queue.push(image_message);
+                    image_message.cnt = 0;
+                    if (status_message.state != 2) {
+                        status_message.state = 2;
+                        shared_memory.application_queue.push(status_message);
+                    }
+                }
+            }
+        }
+    }
+}
+
+void NoaaAptRx::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::NoaaAptRxConfigure:
+            configure(*reinterpret_cast<const NoaaAptRxConfigureMessage*>(message));
+            break;
+
+        case Message::ID::CaptureConfig:
+            capture_config(*reinterpret_cast<const CaptureConfigMessage*>(message));
+            break;
+
+        default:
+            break;
+    }
+}
+
+void NoaaAptRx::configure(const NoaaAptRxConfigureMessage& message) {
+    (void)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 decim_1_input_fs = decim_0_output_fs;
+
+    decim_0.configure(taps_16k0_decim_0.taps);
+
+    // decim_1.configure(message.decim_1_filter.taps);  // Original .
+    // TODO dynamic decim1 ,  with decimation 2 / 8 and  16 x taps , / 32 taps .
+    // Temptatively , I splitted, in two WidebandFMAudio::configure_wfm / WidebandFMAudio::configure_wfmam  and dynamically /2, /8 . (here /8)
+    // decim_1.set<dsp::decimate::FIRC16xR16x16Decim2>().configure(message.decim_1_filter.taps);  // for wfm
+    // decim_1.set<dsp::decimate::FIRC16xR16x32Decim8>().configure(message.decim_1_filter.taps);    // for wfmam
+    decim_1.configure(taps_84k_wfmam_decim_1.taps);                           // for wfmam
+    size_t decim_1_output_fs = decim_1_input_fs / decim_1.decimation_factor;  // wfmam,  decim_1.decimation_factor() = /8 ,if applied after the line, decim_1.set<dsp::decimate::FIRC16xR16x16Decim2>().configure(message.decim_1_filter.taps);
+    size_t demod_input_fs = decim_1_output_fs;
+
+    // spectrum_interval_samples = decim_1_output_fs / spectrum_rate_hz;
+    // spectrum_samples = 0;
+
+    channel_filter_low_f = taps_84k_wfmam_decim_1.low_frequency_normalized * decim_1_input_fs;
+    channel_filter_high_f = taps_84k_wfmam_decim_1.high_frequency_normalized * decim_1_input_fs;
+    channel_filter_transition = taps_84k_wfmam_decim_1.transition_normalized * decim_1_input_fs;
+    demod.configure(demod_input_fs, 17000);
+    audio_filter.configure(taps_64_lp_1875_2166.taps);
+    audio_output.configure(apt_audio_12k_notch_2k4_config, apt_audio_12k_lpf_2000hz_config);
+    // channel_spectrum.set_decimation_factor(1);
+    update_params();
+    configured = true;
+}
+
+void NoaaAptRx::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<NoaaAptRx>()};
+    event_dispatcher.run();
+    return 0;
+}

firmware/baseband/proc_noaaapt_rx.hpp

@@ -0,0 +1,124 @@
+/*
+ * Copyright (C) 2025 Brumi, HTotoo
+ *
+ * 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.
+ */
+
+#ifndef __PROC_NOAAAPTRX_H__
+#define __PROC_NOAAAPTRX_H__
+
+#include "baseband_processor.hpp"
+#include "baseband_thread.hpp"
+#include "rssi_thread.hpp"
+
+#include "dsp_decimate.hpp"
+#include "dsp_demodulate.hpp"
+#include "dsp_iir.hpp"
+#include "audio_compressor.hpp"
+
+#include "audio_output.hpp"
+#include "spectrum_collector.hpp"
+
+#include <cstdint>
+
+class NoaaAptRx : public BasebandProcessor {
+   public:
+    void execute(const buffer_c8_t& buffer) override;
+    void on_message(const Message* const message) override;
+
+   private:
+    void update_params();
+    // todo rethink
+
+    uint32_t samples_per_pixel = 0;
+
+    // to exactly match the pixel / samples.
+    double pxRem = 0;   // if has remainder, it'll store it
+    double pxRoll = 0;  // summs remainders, so won't misalign
+
+    uint32_t cnt = 0;  // signal counter
+    uint16_t sync_cnt = 0;
+    uint16_t syncnot_cnt = 0;
+
+    static constexpr size_t baseband_fs = 3072000;
+    static constexpr auto spectrum_rate_hz = 50.0f;
+
+    std::array<complex16_t, 512> dst{};
+    const buffer_c16_t dst_buffer{
+        dst.data(),
+        dst.size()};
+    // work_audio_buffer and dst_buffer use the same data pointer
+    const buffer_s16_t work_audio_buffer{
+        (int16_t*)dst.data(),
+        sizeof(dst) / sizeof(int16_t)};
+
+    std::array<complex16_t, 64> complex_audio{};
+    const buffer_c16_t complex_audio_buffer{
+        complex_audio.data(),
+        complex_audio.size()};
+
+    dsp::decimate::FIRC8xR16x24FS4Decim4 decim_0{};
+    // dsp::decimate::FIRC16xR16x16Decim2 decim_1{};   //original condition , before adding wfmam
+
+    // decim_1 will handle different types of FIR filters depending on selection.
+    dsp::decimate::FIRC16xR16x32Decim8 decim_1{};
+
+    // dsp::decimate::FIRC16xR16x32Decim8 decim_1{}; // For FMAM
+
+    int32_t channel_filter_low_f = 0;
+    int32_t channel_filter_high_f = 0;
+    int32_t channel_filter_transition = 0;
+
+    dsp::demodulate::FM demod{};
+    dsp::decimate::DecimateBy2CIC4Real audio_dec_1{};
+    dsp::decimate::DecimateBy2CIC4Real audio_dec_2{};
+    dsp::decimate::FIR64AndDecimateBy2Real audio_filter{};
+
+    AudioOutput audio_output{};
+
+    // For fs=96kHz FFT streaming
+    BlockDecimator<complex16_t, 256> audio_spectrum_decimator{1};
+    std::array<std::complex<float>, 256> audio_spectrum{};
+    uint32_t audio_spectrum_timer{0};
+    enum AudioSpectrumState {
+        IDLE = 0,
+        FEED,
+        FFT
+    };
+    AudioSpectrumState audio_spectrum_state{IDLE};
+    AudioSpectrum spectrum{};
+    uint32_t fft_step{0};
+
+    // SpectrumCollector channel_spectrum{};
+    // size_t spectrum_interval_samples = 0;
+    // size_t spectrum_samples = 0;
+
+    bool configured{false};
+
+    void configure(const NoaaAptRxConfigureMessage& message);
+    void capture_config(const CaptureConfigMessage& message);
+
+    NoaaAptRxStatusDataMessage status_message{0};
+    NoaaAptRxImageDataMessage image_message{};
+
+    /* NB: Threads should be the last members in the class definition. */
+    BasebandThread baseband_thread{baseband_fs, this, baseband::Direction::Receive};
+    RSSIThread rssi_thread{};
+};
+
+#endif /*__PROC_NOAAAPTRX_H__*/