Add second pocsag proc for experimenting (#1428)

firmware/application/apps/pocsag_app.cpp

@@ -54,7 +54,8 @@ POCSAGSettingsView::POCSAGSettingsView(
     POCSAGSettings& settings)
     : settings_{settings} {
     add_children(
-        {&check_log,
+        {&check_beta,
+         &check_log,
          &check_log_raw,
          &check_small_font,
          &check_hide_bad,
@@ -63,6 +64,7 @@ POCSAGSettingsView::POCSAGSettingsView(
          &field_ignore,
          &button_save});
 
+    check_beta.set_value(settings_.use_new_proc);
     check_log.set_value(settings_.enable_logging);
     check_log_raw.set_value(settings_.enable_raw_log);
     check_small_font.set_value(settings_.enable_small_font);
@@ -72,6 +74,7 @@ POCSAGSettingsView::POCSAGSettingsView(
     field_ignore.set_value(settings_.address_to_ignore);
 
     button_save.on_select = [this, &nav](Button&) {
+        settings_.use_new_proc = check_beta.value();
         settings_.enable_logging = check_log.value();
         settings_.enable_raw_log = check_log_raw.value();
         settings_.enable_small_font = check_small_font.value();
@@ -86,7 +89,10 @@ POCSAGSettingsView::POCSAGSettingsView(
 
 POCSAGAppView::POCSAGAppView(NavigationView& nav)
     : nav_{nav} {
-    baseband::run_image(portapack::spi_flash::image_tag_pocsag);
+    if (settings_.use_new_proc)
+        baseband::run_image(portapack::spi_flash::image_tag_pocsag2);
+    else
+        baseband::run_image(portapack::spi_flash::image_tag_pocsag);
 
     add_children(
         {&rssi,

firmware/application/apps/pocsag_app.hpp

@@ -60,6 +60,7 @@ struct POCSAGSettings {
     bool hide_bad_data = false;
     bool hide_addr_only = false;
     uint32_t address_to_ignore = 0;
+    bool use_new_proc = false;
 };
 
 class POCSAGSettingsView : public View {
@@ -67,45 +68,46 @@ class POCSAGSettingsView : public View {
     POCSAGSettingsView(NavigationView& nav, POCSAGSettings& settings);
 
     std::string title() const override { return "POCSAG Config"; };
+    void focus() override { button_save.focus(); }
 
    private:
     POCSAGSettings& settings_;
 
+    Checkbox check_beta{
+        {0 * 8 + 2, 18 * 16 - 4},
+        6,
+        "Beta",
+        true /*small*/};
+
     Checkbox check_log{
         {2 * 8, 2 * 16},
         10,
-        "Enable Log",
+        "Enable Log"};
-        false};
 
     Checkbox check_log_raw{
         {2 * 8, 4 * 16},
         12,
-        "Log Raw Data",
+        "Log Raw Data"};
-        false};
 
     Checkbox check_small_font{
         {2 * 8, 6 * 16},
         4,
-        "Use Small Font",
+        "Use Small Font"};
-        false};
 
     Checkbox check_hide_bad{
         {2 * 8, 8 * 16},
         22,
-        "Hide Bad Data",
+        "Hide Bad Data"};
-        false};
 
     Checkbox check_hide_addr_only{
         {2 * 8, 10 * 16},
         22,
-        "Hide Addr Only",
+        "Hide Addr Only"};
-        false};
 
     Checkbox check_ignore{
         {2 * 8, 12 * 16},
         22,
-        "Enable Ignored Address",
+        "Enable Ignored Address"};
-        false};
 
     NumberField field_ignore{
         {7 * 8, 13 * 16 + 8},
@@ -115,7 +117,7 @@ class POCSAGSettingsView : public View {
         '0'};
 
     Button button_save{
-        {12 * 8, 16 * 16, 10 * 8, 2 * 16},
+        {11 * 8, 16 * 16, 10 * 8, 2 * 16},
         "Save"};
 };
 
@@ -150,6 +152,7 @@ class POCSAGAppView : public View {
             {"address_to_ignore"sv, &settings_.address_to_ignore},
             {"hide_bad_data"sv, &settings_.hide_bad_data},
             {"hide_addr_only"sv, &settings_.hide_addr_only},
+            {"use_new_proc"sv, &settings_.use_new_proc},
         }};
 
     void refresh_ui();

firmware/baseband/CMakeLists.txt

@@ -444,6 +444,13 @@ set(MODE_CPPSRC
 )
 DeclareTargets(PPOC pocsag)
 
+### POCSAG2 RX
+
+set(MODE_CPPSRC
+	proc_pocsag2.cpp
+)
+DeclareTargets(PPOC pocsag2)
+
 ### RDS
 
 set(MODE_CPPSRC

firmware/baseband/dsp_squelch.cpp

@@ -36,6 +36,7 @@ bool FMSquelch::execute(const buffer_f32_t& audio) {
         squelch_energy_buffer.size()};
     non_audio_hpf.execute(audio, squelch_energy);
 
+    // "Non-audio" implies "noise" here. Find the loudest noise sample.
     float non_audio_max_squared = 0;
     for (const auto sample : squelch_energy_buffer) {
         const float sample_squared = sample * sample;
@@ -44,9 +45,14 @@ bool FMSquelch::execute(const buffer_f32_t& audio) {
         }
     }
 
+    // Is the noise less than the threshold?
     return (non_audio_max_squared < threshold_squared);
 }
 
 void FMSquelch::set_threshold(const float new_value) {
     threshold_squared = new_value * new_value;
 }
+
+bool FMSquelch::enabled() const {
+    return threshold_squared > 0.0;
+}

firmware/baseband/dsp_squelch.hpp

@@ -31,9 +31,12 @@
 
 class FMSquelch {
    public:
+    /* Check if noise level is lower than threshold.
+     * Returns true if noise is below threshold. */
     bool execute(const buffer_f32_t& audio);
 
     void set_threshold(const float new_value);
+    bool enabled() const;
 
    private:
     static constexpr size_t N = 32;

firmware/baseband/proc_pocsag.cpp

@@ -3,6 +3,7 @@
  * Copyright (C) 2012-2014 Elias Oenal (multimon-ng@eliasoenal.com)
  * Copyright (C) 2015 Jared Boone, ShareBrained Technology, Inc.
  * Copyright (C) 2016 Furrtek
+ * Copyright (C) 2016 Kyle Reed
  *
  * This file is part of PortaPack.
  *
@@ -41,16 +42,29 @@ void POCSAGProcessor::execute(const buffer_c8_t& buffer) {
     const auto channel_out = channel_filter.execute(decim_1_out, dst_buffer);
     auto audio = demod.execute(channel_out, audio_buffer);
 
-    // When use_squelch_ is true, AudioOutput applies filters
+    // If squelching, check for audio before smoothing because smoothing
-    // which should eliminate the need to do this smoothing.
+    // causes the squelch noise detection to fail. Likely because squelch
-    if (use_squelch_ == false)
+    // looks for HF noise and smoothing is basically a lowpass filter.
-        smooth.Process(audio.p, audio.count);
+    // NB: Squelch in this processor is only for the the audio output.
-
+    // Squelching will likely drop data "noise" and break processing.
-    // NB: This applies audio filters in-place when use_squelch_ is true.
+    if (squelch_.enabled()) {
-    audio_output.write(audio);
+        bool has_audio = squelch_.execute(audio);
+        squelch_history = (squelch_history << 1) | (has_audio ? 1 : 0);
+    }
 
+    smooth.Process(audio.p, audio.count);
     processDemodulatedSamples(audio.p, 16);
     extractFrames();
+
+    // Clear the output before sending to audio chip.
+    // Only clear the audio buffer when there hasn't been any audio for a while.
+    if (squelch_.enabled() && squelch_history == 0) {
+        for (size_t i = 0; i < audio.count; ++i) {
+            audio.p[i] = 0.0;
+        }
+    }
+
+    audio_output.write(audio);
 }
 
 // ====================================================================
@@ -83,13 +97,7 @@ void POCSAGProcessor::on_message(const Message* const message) {
 
         case Message::ID::NBFMConfigure: {
             auto config = reinterpret_cast<const NBFMConfigureMessage*>(message);
-
+            squelch_.set_threshold(config->squelch_level / 100.0);
-            use_squelch_ = config->squelch_level > 0;
-            audio_output.configure(
-                audio_24k_hpf_300hz_config,
-                audio_24k_lpf_2400hz_config,
-                config->squelch_level / 100.0);
-            audio_output.configure(use_squelch_);
             break;
         }
 
@@ -119,6 +127,9 @@ void POCSAGProcessor::configure() {
     // 24k / 3.2k = 7.5
     smooth.SetSize(8);
 
+    // Don't have audio process the stream.
+    audio_output.configure(false);
+
     // Set up the frame extraction, limits of baud
     setFrameExtractParams(demod_input_fs, 4000, 300, 32);
 

firmware/baseband/proc_pocsag.hpp

@@ -3,6 +3,7 @@
  * Copyright (C) 2012-2014 Elias Oenal (multimon-ng@eliasoenal.com)
  * Copyright (C) 2015 Jared Boone, ShareBrained Technology, Inc.
  * Copyright (C) 2016 Furrtek
+ * Copyright (C) 2023 Kyle Reed
  *
  * This file is part of PortaPack.
  *
@@ -215,7 +216,8 @@ class POCSAGProcessor : public BasebandProcessor {
     int m_numCode{0};
     bool m_inverted{false};
 
-    bool use_squelch_ = false;
+    FMSquelch squelch_{};
+    uint64_t squelch_history = 0;
 
     /* NB: Threads should be the last members in the class definition. */
     BasebandThread baseband_thread{baseband_fs, this, baseband::Direction::Receive};

firmware/baseband/proc_pocsag2.cpp

@@ -0,0 +1,524 @@
+/*
+ * Copyright (C) 1996 Thomas Sailer (sailer@ife.ee.ethz.ch, hb9jnx@hb9w.che.eu)
+ * Copyright (C) 2012-2014 Elias Oenal (multimon-ng@eliasoenal.com)
+ * Copyright (C) 2015 Jared Boone, ShareBrained Technology, Inc.
+ * Copyright (C) 2016 Furrtek
+ * Copyright (C) 2016 Kyle Reed
+ *
+ * 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_pocsag2.hpp"
+
+#include "dsp_iir_config.hpp"
+#include "event_m4.hpp"
+
+#include <algorithm>
+#include <cmath>
+#include <cstdint>
+#include <cstddef>
+
+void POCSAGProcessor::execute(const buffer_c8_t& buffer) {
+    if (!configured) return;
+
+    // Get 24kHz audio
+    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);
+    auto audio = demod.execute(channel_out, audio_buffer);
+
+    // If squelching, check for audio before smoothing because smoothing
+    // causes the squelch noise detection to fail. Likely because squelch
+    // looks for HF noise and smoothing is basically a lowpass filter.
+    // NB: Squelch in this processor is only for the the audio output.
+    // Squelching will likely drop data "noise" and break processing.
+    if (squelch_.enabled()) {
+        bool has_audio = squelch_.execute(audio);
+        squelch_history = (squelch_history << 1) | (has_audio ? 1 : 0);
+    }
+
+    smooth.Process(audio.p, audio.count);
+    processDemodulatedSamples(audio.p, 16);
+    extractFrames();
+
+    // Clear the output before sending to audio chip.
+    if (squelch_.enabled() && squelch_history == 0) {
+        for (size_t i = 0; i < audio.count; ++i) {
+            audio.p[i] = 0.0;
+        }
+    }
+
+    audio_output.write(audio);
+}
+
+// ====================================================================
+//
+// ====================================================================
+int POCSAGProcessor::OnDataWord(uint32_t word, int pos) {
+    packet.set(pos, word);
+    return 0;
+}
+
+// ====================================================================
+//
+// ====================================================================
+int POCSAGProcessor::OnDataFrame(int len, int baud) {
+    if (len > 0) {
+        packet.set_bitrate(baud);
+        packet.set_flag(pocsag::PacketFlag::NORMAL);
+        packet.set_timestamp(Timestamp::now());
+        const POCSAGPacketMessage message(packet);
+        shared_memory.application_queue.push(message);
+    }
+    return 0;
+}
+
+void POCSAGProcessor::on_message(const Message* const message) {
+    switch (message->id) {
+        case Message::ID::POCSAGConfigure:
+            configure();
+            break;
+
+        case Message::ID::NBFMConfigure: {
+            auto config = reinterpret_cast<const NBFMConfigureMessage*>(message);
+            squelch_.set_threshold(config->squelch_level / 100.0);
+            break;
+        }
+
+        default:
+            break;
+    }
+}
+
+void POCSAGProcessor::configure() {
+    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;
+    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;
+    const size_t channel_filter_output_fs = channel_filter_input_fs / 2;
+
+    const size_t demod_input_fs = channel_filter_output_fs;
+
+    decim_0.configure(taps_11k0_decim_0.taps);
+    decim_1.configure(taps_11k0_decim_1.taps);
+    channel_filter.configure(taps_11k0_channel.taps, 2);
+    demod.configure(demod_input_fs, 4'500);  // FSK +/- 4k5Hz.
+
+    // Smoothing should be roughly sample rate over max baud
+    // 24k / 3.2k = 7.5
+    smooth.SetSize(8);
+
+    // Don't have audio process the stream.
+    audio_output.configure(false);
+
+    // Set up the frame extraction, limits of baud
+    setFrameExtractParams(demod_input_fs, 4000, 300, 32);
+
+    // Mark the class as ready to accept data
+    configured = true;
+}
+
+// -----------------------------
+// Frame extractraction methods
+// -----------------------------
+#define BAUD_STABLE (104)
+#define MAX_CONSEC_SAME (32)
+#define MAX_WITHOUT_SINGLE (64)
+#define MAX_BAD_TRANS (10)
+
+#define M_SYNC (0x7cd215d8)
+#define M_NOTSYNC (0x832dea27)
+
+#define M_IDLE (0x7a89c197)
+
+// ====================================================================
+//
+// ====================================================================
+inline int bitsDiff(unsigned long left, unsigned long right) {
+    unsigned long xord = left ^ right;
+    int count = 0;
+    for (int i = 0; i < 32; i++) {
+        if ((xord & 0x01) != 0) ++count;
+        xord = xord >> 1;
+    }
+    return (count);
+}
+
+// ====================================================================
+//
+// ====================================================================
+void POCSAGProcessor::initFrameExtraction() {
+    m_averageSymbolLen_1024 = m_maxSymSamples_1024;
+    m_lastStableSymbolLen_1024 = m_minSymSamples_1024;
+
+    m_badTransitions = 0;
+    m_bitsStart = 0;
+    m_bitsEnd = 0;
+    m_inverted = false;
+
+    resetVals();
+}
+
+// ====================================================================
+//
+// ====================================================================
+void POCSAGProcessor::resetVals() {
+    // Reset the parameters
+    // --------------------
+    m_goodTransitions = 0;
+    m_badTransitions = 0;
+    m_averageSymbolLen_1024 = m_maxSymSamples_1024;
+    m_shortestGoodTrans_1024 = m_maxSymSamples_1024;
+    m_valMid = 0;
+
+    // And reset the counts
+    // --------------------
+    m_lastTransPos_1024 = 0;
+    m_lastBitPos_1024 = 0;
+    m_lastSample = 0;
+    m_sampleNo = 0;
+    m_nextBitPos_1024 = m_maxSymSamples_1024;
+    m_nextBitPosInt = (long)m_nextBitPos_1024;
+
+    // Extraction
+    m_fifo.numBits = 0;
+    m_gotSync = false;
+    m_numCode = 0;
+}
+
+// ====================================================================
+//
+// ====================================================================
+void POCSAGProcessor::setFrameExtractParams(long a_samplesPerSec, long a_maxBaud, long a_minBaud, long maxRunOfSameValue) {
+    m_samplesPerSec = a_samplesPerSec;
+    m_minSymSamples_1024 = (uint32_t)(1024.0f * (float)a_samplesPerSec / (float)a_maxBaud);
+    m_maxSymSamples_1024 = (uint32_t)(1024.0f * (float)a_samplesPerSec / (float)a_minBaud);
+    m_maxRunOfSameValue = maxRunOfSameValue;
+
+    m_shortestGoodTrans_1024 = m_maxSymSamples_1024;
+    m_averageSymbolLen_1024 = m_maxSymSamples_1024;
+    m_lastStableSymbolLen_1024 = m_minSymSamples_1024;
+
+    m_nextBitPos_1024 = m_averageSymbolLen_1024 / 2;
+    m_nextBitPosInt = m_nextBitPos_1024 >> 10;
+
+    initFrameExtraction();
+}
+
+// ====================================================================
+//
+// ====================================================================
+int POCSAGProcessor::processDemodulatedSamples(float* sampleBuff, int noOfSamples) {
+    bool transition = false;
+    uint32_t samplePos_1024 = 0;
+    uint32_t len_1024 = 0;
+
+    // Loop through the block of data
+    // ------------------------------
+    for (int pos = 0; pos < noOfSamples; ++pos) {
+        m_sample = sampleBuff[pos];
+        m_valMid += (m_sample - m_valMid) / 1024.0f;
+
+        ++m_sampleNo;
+
+        // Detect Transition
+        // -----------------
+        transition = !((m_lastSample < m_valMid) ^ (m_sample >= m_valMid));  // use XOR for speed
+
+        // If this is a transition
+        // -----------------------
+        if (transition) {
+            // Calculate samples since last trans
+            // ----------------------------------
+            int32_t fractional_1024 = (int32_t)(((m_sample - m_valMid) * 1024) / (m_sample - m_lastSample));
+            if (fractional_1024 < 0) {
+                fractional_1024 = -fractional_1024;
+            }
+
+            samplePos_1024 = (m_sampleNo << 10) - fractional_1024;
+            len_1024 = samplePos_1024 - m_lastTransPos_1024;
+            m_lastTransPos_1024 = samplePos_1024;
+
+            // If symbol is large enough to be valid
+            // -------------------------------------
+            if (len_1024 > m_minSymSamples_1024) {
+                // Check for shortest good transition
+                // ----------------------------------
+                if ((len_1024 < m_shortestGoodTrans_1024) &&
+                    (m_goodTransitions < BAUD_STABLE))  // detect change of symbol size
+                {
+                    int32_t fractionOfShortest_1024 = (len_1024 << 10) / m_shortestGoodTrans_1024;
+
+                    // If currently at half the baud rate
+                    // ----------------------------------
+                    if ((fractionOfShortest_1024 > 410) && (fractionOfShortest_1024 < 614))  // 0.4 and 0.6
+                    {
+                        m_averageSymbolLen_1024 /= 2;
+                        m_shortestGoodTrans_1024 = len_1024;
+                    }
+                    // If currently at the wrong baud rate
+                    // -----------------------------------
+                    else if (fractionOfShortest_1024 < 768)  // 0.75
+                    {
+                        m_averageSymbolLen_1024 = len_1024;
+                        m_shortestGoodTrans_1024 = len_1024;
+                        m_goodTransitions = 0;
+                        m_lastSingleBitPos_1024 = samplePos_1024 - len_1024;
+                    }
+                }
+
+                // Calc the number of bits since events
+                // ------------------------------------
+                int32_t halfSymbol_1024 = m_averageSymbolLen_1024 / 2;
+                int bitsSinceLastTrans = max((uint32_t)1, (len_1024 + halfSymbol_1024) / m_averageSymbolLen_1024);
+                int bitsSinceLastSingle = (((m_sampleNo << 10) - m_lastSingleBitPos_1024) + halfSymbol_1024) / m_averageSymbolLen_1024;
+
+                // Check for single bit
+                // --------------------
+                if (bitsSinceLastTrans == 1) {
+                    m_lastSingleBitPos_1024 = samplePos_1024;
+                }
+
+                // If too long since last transition
+                // ---------------------------------
+                if (bitsSinceLastTrans > MAX_CONSEC_SAME) {
+                    resetVals();
+                }
+                // If too long sice last single bit
+                // --------------------------------
+                else if (bitsSinceLastSingle > MAX_WITHOUT_SINGLE) {
+                    resetVals();
+                } else {
+                    // If this is a good transition
+                    // ----------------------------
+                    int32_t offsetFromExtectedTransition_1024 = len_1024 - (bitsSinceLastTrans * m_averageSymbolLen_1024);
+                    if (offsetFromExtectedTransition_1024 < 0) {
+                        offsetFromExtectedTransition_1024 = -offsetFromExtectedTransition_1024;
+                    }
+                    if (offsetFromExtectedTransition_1024 < ((int32_t)m_averageSymbolLen_1024 / 4))  // Has to be within 1/4 of symbol to be good
+                    {
+                        ++m_goodTransitions;
+                        uint32_t bitsCount = min((uint32_t)BAUD_STABLE, m_goodTransitions);
+
+                        uint32_t propFromPrevious = m_averageSymbolLen_1024 * bitsCount;
+                        uint32_t propFromCurrent = (len_1024 / bitsSinceLastTrans);
+                        m_averageSymbolLen_1024 = (propFromPrevious + propFromCurrent) / (bitsCount + 1);
+                        m_badTransitions = 0;
+                        // if ( len < m_shortestGoodTrans ){m_shortestGoodTrans = len;}
+                        //  Store the old symbol size
+                        if (m_goodTransitions >= BAUD_STABLE) {
+                            m_lastStableSymbolLen_1024 = m_averageSymbolLen_1024;
+                        }
+                    }
+                }
+
+                // Set the point of the last bit if not yet stable
+                // -----------------------------------------------
+                if ((m_goodTransitions < BAUD_STABLE) || (m_badTransitions > 0)) {
+                    m_lastBitPos_1024 = samplePos_1024 - (m_averageSymbolLen_1024 / 2);
+                }
+
+                // Calculate the exact positiom of the next bit
+                // --------------------------------------------
+                int32_t thisPlusHalfsymbol_1024 = samplePos_1024 + (m_averageSymbolLen_1024 / 2);
+                int32_t lastPlusSymbol = m_lastBitPos_1024 + m_averageSymbolLen_1024;
+                m_nextBitPos_1024 = lastPlusSymbol + ((thisPlusHalfsymbol_1024 - lastPlusSymbol) / 16);
+
+                // Check for bad pos error
+                // -----------------------
+                if (m_nextBitPos_1024 < samplePos_1024) m_nextBitPos_1024 += m_averageSymbolLen_1024;
+
+                // Calculate integer sample after next bit
+                // ---------------------------------------
+                m_nextBitPosInt = (m_nextBitPos_1024 >> 10) + 1;
+
+            }  // symbol is large enough to be valid
+            else {
+                // Bad transition, so reset the counts
+                // -----------------------------------
+                ++m_badTransitions;
+                if (m_badTransitions > MAX_BAD_TRANS) {
+                    resetVals();
+                }
+            }
+        }  // end of if transition
+
+        // Reached the point of the next bit
+        // ---------------------------------
+        if (m_sampleNo >= m_nextBitPosInt) {
+            // Everything is good so extract a bit
+            // -----------------------------------
+            if (m_goodTransitions > 20) {
+                // Store value at the center of bit
+                // --------------------------------
+                storeBit();
+            }
+            // Check for long 1 or zero
+            // ------------------------
+            uint32_t bitsSinceLastTrans = ((m_sampleNo << 10) - m_lastTransPos_1024) / m_averageSymbolLen_1024;
+            if (bitsSinceLastTrans > m_maxRunOfSameValue) {
+                resetVals();
+            }
+
+            // Store the point of the last bit
+            // -------------------------------
+            m_lastBitPos_1024 = m_nextBitPos_1024;
+
+            // Calculate the exact point of the next bit
+            // -----------------------------------------
+            m_nextBitPos_1024 += m_averageSymbolLen_1024;
+
+            // Look for the bit after the next bit pos
+            // ---------------------------------------
+            m_nextBitPosInt = (m_nextBitPos_1024 >> 10) + 1;
+
+        }  // Reached the point of the next bit
+
+        m_lastSample = m_sample;
+
+    }  // Loop through the block of data
+
+    return getNoOfBits();
+}
+
+// ====================================================================
+//
+// ====================================================================
+void POCSAGProcessor::storeBit() {
+    if (++m_bitsStart >= BIT_BUF_SIZE) {
+        m_bitsStart = 0;
+    }
+
+    // Calculate the bit value
+    float sample = (m_sample + m_lastSample) / 2;
+    // int32_t sample_1024 = m_sample_1024;
+    bool bit = sample > m_valMid;
+
+    // If buffer not full
+    if (m_bitsStart != m_bitsEnd) {
+        // Decide on output val
+        if (bit) {
+            m_bits[m_bitsStart] = 0;
+        } else {
+            m_bits[m_bitsStart] = 1;
+        }
+    }
+    // Throw away bits if the buffer is full
+    else {
+        if (--m_bitsStart <= -1) {
+            m_bitsStart = BIT_BUF_SIZE - 1;
+        }
+    }
+}
+
+// ====================================================================
+//
+// ====================================================================
+int POCSAGProcessor::extractFrames() {
+    int msgCnt = 0;
+    // While there is unread data in the bits buffer
+    //----------------------------------------------
+    while (getNoOfBits() > 0) {
+        m_fifo.codeword = (m_fifo.codeword << 1) + getBit();
+        m_fifo.numBits++;
+
+        // If number of bits in fifo equals 32
+        //------------------------------------
+        if (m_fifo.numBits >= 32) {
+            // Not got sync
+            // ------------
+            if (!m_gotSync) {
+                if (bitsDiff(m_fifo.codeword, M_SYNC) <= 2) {
+                    m_inverted = false;
+                    m_gotSync = true;
+                    m_numCode = -1;
+                    m_fifo.numBits = 0;
+                } else if (bitsDiff(m_fifo.codeword, M_NOTSYNC) <= 2) {
+                    m_inverted = true;
+                    m_gotSync = true;
+                    m_numCode = -1;
+                    m_fifo.numBits = 0;
+                } else {
+                    // Cause it to load one more bit
+                    m_fifo.numBits = 31;
+                }
+            }  // Not got sync
+            else {
+                // Increment the word count
+                // ------------------------
+                ++m_numCode;  // It got set to -1 when a sync was found, now count the 16 words
+                uint32_t val = m_inverted ? ~m_fifo.codeword : m_fifo.codeword;
+                OnDataWord(val, m_numCode);
+
+                // If at the end of a 16 word block
+                // --------------------------------
+                if (m_numCode >= 15) {
+                    msgCnt += OnDataFrame(m_numCode + 1, (m_samplesPerSec << 10) / m_lastStableSymbolLen_1024);
+                    m_gotSync = false;
+                    m_numCode = -1;
+                }
+                m_fifo.numBits = 0;
+            }
+        }  // If number of bits in fifo equals 32
+    }      // While there is unread data in the bits buffer
+    return msgCnt;
+}  // extractFrames
+
+// ====================================================================
+//
+// ====================================================================
+short POCSAGProcessor::getBit() {
+    if (m_bitsEnd != m_bitsStart) {
+        if (++m_bitsEnd >= BIT_BUF_SIZE) {
+            m_bitsEnd = 0;
+        }
+        return m_bits[m_bitsEnd];
+    } else {
+        return -1;
+    }
+}
+
+// ====================================================================
+//
+// ====================================================================
+int POCSAGProcessor::getNoOfBits() {
+    int bits = m_bitsEnd - m_bitsStart;
+    if (bits < 0) {
+        bits += BIT_BUF_SIZE;
+    }
+    return bits;
+}
+
+// ====================================================================
+//
+// ====================================================================
+uint32_t POCSAGProcessor::getRate() {
+    return ((m_samplesPerSec << 10) + 512) / m_lastStableSymbolLen_1024;
+}
+
+// ====================================================================
+//
+// ====================================================================
+int main() {
+    EventDispatcher event_dispatcher{std::make_unique<POCSAGProcessor>()};
+    event_dispatcher.run();
+    return 0;
+}

firmware/baseband/proc_pocsag2.hpp

@@ -0,0 +1,227 @@
+/*
+ * Copyright (C) 1996 Thomas Sailer (sailer@ife.ee.ethz.ch, hb9jnx@hb9w.che.eu)
+ * Copyright (C) 2012-2014 Elias Oenal (multimon-ng@eliasoenal.com)
+ * Copyright (C) 2015 Jared Boone, ShareBrained Technology, Inc.
+ * Copyright (C) 2016 Furrtek
+ * Copyright (C) 2023 Kyle Reed
+ *
+ * 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_POCSAG2_H__
+#define __PROC_POCSAG2_H__
+
+#include "baseband_processor.hpp"
+#include "baseband_thread.hpp"
+#include "rssi_thread.hpp"
+
+#include "dsp_decimate.hpp"
+#include "dsp_demodulate.hpp"
+
+#include "pocsag_packet.hpp"
+
+#include "pocsag.hpp"
+#include "message.hpp"
+#include "audio_output.hpp"
+#include "portapack_shared_memory.hpp"
+
+#include <cstdint>
+#include <bitset>
+using namespace std;
+
+// Class used to smooth demodulated waveform prior to decoding
+// -----------------------------------------------------------
+template <class ValType, class CalcType>
+class SmoothVals {
+   protected:
+    ValType* m_lastVals;  // Previous N values
+    int m_size;           // The size N
+    CalcType m_sumVal;    // Running sum of lastVals
+    int m_pos;            // Current position in last vals ring buffer
+    int m_count;          //
+
+   public:
+    SmoothVals()
+        : m_lastVals(NULL), m_size(1), m_sumVal(0), m_pos(0), m_count(0) {
+        m_lastVals = new ValType[m_size];
+    }
+
+    // --------------------------------------------------
+    // --------------------------------------------------
+    virtual ~SmoothVals() {
+        delete[] m_lastVals;
+    }
+
+    SmoothVals(const SmoothVals<float, float>&) {
+    }
+
+    SmoothVals& operator=(const SmoothVals<float, float>&) {
+        return *this;
+    }
+
+    // --------------------------------------------------
+    // Set size of smoothing
+    // --------------------------------------------------
+    void SetSize(int size) {
+        m_size = std::max(size, 1);
+        m_pos = 0;
+        delete[] m_lastVals;
+        m_lastVals = new ValType[m_size];
+        m_sumVal = 0;
+    }
+
+    // --------------------------------------------------
+    // Get size of smoothing
+    // --------------------------------------------------
+    int Size() { return m_size; }
+
+    // --------------------------------------------------
+    // In place processing
+    // --------------------------------------------------
+    void Process(ValType* valBuff, int numVals) {
+        ValType tmpVal;
+
+        if (m_count > (1024 * 10)) {
+            // Recalculate the sum value occasionaly, stops accumulated errors when using float
+            m_count = 0;
+            m_sumVal = 0;
+            for (int i = 0; i < m_size; ++i) {
+                m_sumVal += (CalcType)m_lastVals[i];
+            }
+        }
+
+        // Use a rolling smoothed value while processing the buffer
+        for (int buffPos = 0; buffPos < numVals; ++buffPos) {
+            m_pos++;
+            if (m_pos >= m_size) {
+                m_pos = 0;
+            }
+
+            m_sumVal -= (CalcType)m_lastVals[m_pos];  // Subtract the oldest value
+            m_lastVals[m_pos] = valBuff[buffPos];     // Store the new value
+            m_sumVal += (CalcType)m_lastVals[m_pos];  // Add on the new value
+
+            tmpVal = (ValType)(m_sumVal / m_size);  // Scale by number of values smoothed
+            valBuff[buffPos] = tmpVal;
+        }
+
+        m_count += numVals;
+    }
+};
+
+// --------------------------------------------------
+// Class to process base band data to pocsag frames
+// --------------------------------------------------
+class POCSAGProcessor : public BasebandProcessor {
+   public:
+    void execute(const buffer_c8_t& buffer) override;
+    void on_message(const Message* const message) override;
+
+    int OnDataFrame(int len, int baud);
+    int OnDataWord(uint32_t word, int pos);
+
+   private:
+    static constexpr size_t baseband_fs = 3072000;
+
+    std::array<complex16_t, 512> dst{};
+    const buffer_c16_t dst_buffer{
+        dst.data(),
+        dst.size()};
+    std::array<float, 32> audio{};
+    const buffer_f32_t audio_buffer{
+        audio.data(),
+        audio.size()};
+
+    dsp::decimate::FIRC8xR16x24FS4Decim8 decim_0{};
+    dsp::decimate::FIRC16xR16x32Decim8 decim_1{};
+    dsp::decimate::FIRAndDecimateComplex channel_filter{};
+    dsp::demodulate::FM demod{};
+    SmoothVals<float, float> smooth = {};
+
+    AudioOutput audio_output{};
+
+    bool configured = false;
+    pocsag::POCSAGPacket packet{};
+
+    void configure();
+
+    // ----------------------------------------
+    // Frame extractraction methods and members
+    // ----------------------------------------
+    void initFrameExtraction();
+    struct FIFOStruct {
+        unsigned long codeword;
+        int numBits;
+    };
+
+#define BIT_BUF_SIZE (64)
+
+    void resetVals();
+    void setFrameExtractParams(long a_samplesPerSec, long a_maxBaud = 8000, long a_minBaud = 200, long maxRunOfSameValue = 32);
+
+    int processDemodulatedSamples(float* sampleBuff, int noOfSamples);
+    int extractFrames();
+
+    void storeBit();
+    short getBit();
+
+    int getNoOfBits();
+    uint32_t getRate();
+
+    uint32_t m_averageSymbolLen_1024{0};
+    uint32_t m_lastStableSymbolLen_1024{0};
+
+    uint32_t m_samplesPerSec{0};
+    uint32_t m_goodTransitions{0};
+    uint32_t m_badTransitions{0};
+
+    uint32_t m_sampleNo{0};
+    float m_sample{0};
+    float m_valMid{0.0f};
+    float m_lastSample{0.0f};
+
+    uint32_t m_lastTransPos_1024{0};
+    uint32_t m_lastSingleBitPos_1024{0};
+
+    uint32_t m_nextBitPosInt{0};  // Integer rounded up version to save on ops
+    uint32_t m_nextBitPos_1024{0};
+    uint32_t m_lastBitPos_1024{0};
+
+    uint32_t m_shortestGoodTrans_1024{0};
+    uint32_t m_minSymSamples_1024{0};
+    uint32_t m_maxSymSamples_1024{0};
+    uint32_t m_maxRunOfSameValue{0};
+
+    bitset<(size_t)BIT_BUF_SIZE> m_bits{0};
+    long m_bitsStart{0};
+    long m_bitsEnd{0};
+
+    FIFOStruct m_fifo{0, 0};
+    bool m_gotSync{false};
+    int m_numCode{0};
+    bool m_inverted{false};
+
+    FMSquelch squelch_{};
+    uint64_t squelch_history = 0;
+
+    /* 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_POCSAG2_H__*/

firmware/common/spi_image.hpp

@@ -86,6 +86,7 @@ constexpr image_tag_t image_tag_capture{'P', 'C', 'A', 'P'};
 constexpr image_tag_t image_tag_ert{'P', 'E', 'R', 'T'};
 constexpr image_tag_t image_tag_nfm_audio{'P', 'N', 'F', 'M'};
 constexpr image_tag_t image_tag_pocsag{'P', 'P', 'O', 'C'};
+constexpr image_tag_t image_tag_pocsag2{'P', 'P', 'O', '2'};
 constexpr image_tag_t image_tag_sonde{'P', 'S', 'O', 'N'};
 constexpr image_tag_t image_tag_tpms{'P', 'T', 'P', 'M'};
 constexpr image_tag_t image_tag_wfm_audio{'P', 'W', 'F', 'M'};