Add basic ERT (OOK) utility meter reception.

Extracted the Manchester formatting function for use in ERT, now also returns an indication of bits in error.

firmware/application/receiver_model.cpp

@@ -138,7 +138,8 @@ void ReceiverModel::disable() {
 }
 
 int32_t ReceiverModel::tuning_offset() {
-	if( baseband_configuration.mode == 4 ) {
+	if( (baseband_configuration.mode == 4) ||
+		(baseband_configuration.mode == 6) ) {
 		return 0;
 	} else {
 		return -(sampling_rate() / 4);

firmware/application/ui_receiver.cpp

@@ -512,6 +512,12 @@ void ReceiverView::on_show() {
 			this->on_packet_tpms(*message);
 		}
 	);
+	message_map.register_handler(Message::ID::ERTPacket,
+		[this](Message* const p) {
+			const auto message = static_cast<const ERTPacketMessage*>(p);
+			this->on_packet_ert(*message);
+		}
+	);
 
 	sd_card_status_signal_token = sd_card::status_signal += [this](const sd_card::Status status) {
 		this->on_sd_card_status(status);
@@ -522,6 +528,7 @@ void ReceiverView::on_hide() {
 	sd_card::status_signal -= sd_card_status_signal_token;
 
 	auto& message_map = context().message_map();
+	message_map.unregister_handler(Message::ID::ERTPacket);
 	message_map.unregister_handler(Message::ID::TPMSPacket);
 	message_map.unregister_handler(Message::ID::AISPacket);
 }
@@ -537,16 +544,21 @@ void ReceiverView::on_packet_ais(const AISPacketMessage& message) {
 
 static FIL fil_tpms;
 
-void ReceiverView::on_packet_tpms(const TPMSPacketMessage& message) {
+static std::pair<std::string, std::string> format_manchester(
-	auto payload = message.packet.payload;
+	const uint_fast8_t sense,
-	auto payload_length = message.packet.bits_received;
+	const std::bitset<1024>& payload,
+	const size_t payload_length
+) {
+	const size_t payload_length_decoded = payload_length / 2;
+	const size_t payload_length_bytes = (payload_length_decoded + 7) / 8;
+	const size_t payload_length_symbols_rounded = payload_length_bytes * 8 * 2;
 
 	std::string hex_data;
 	std::string hex_error;
 	uint8_t byte_data = 0;
 	uint8_t byte_error = 0;
-	for(size_t i=0; i<payload_length; i+=2) {
+	for(size_t i=0; i<payload_length_symbols_rounded; i+=2) {
-		const auto bit_data = payload[i+1];
+		const auto bit_data = payload[i+sense];
 		const auto bit_error = (payload[i+0] == payload[i+1]);
 
 		byte_data <<= 1;
@@ -561,8 +573,17 @@ void ReceiverView::on_packet_tpms(const TPMSPacketMessage& message) {
 		}
 	}
 
+	return { hex_data, hex_error };
+}
+
+void ReceiverView::on_packet_tpms(const TPMSPacketMessage& message) {
+	auto payload = message.packet.payload;
+	auto payload_length = message.packet.bits_received;
+
+	const auto hex_formatted = format_manchester(1, payload, payload_length);
+
 	auto console = reinterpret_cast<Console*>(widget_content.get());
-	console->writeln(hex_data.substr(0, 240 / 8));
+	console->writeln(hex_formatted.first.substr(0, 240 / 8));
 
 	if( !f_error(&fil_tpms) ) {
 		rtc::RTC datetime;
@@ -579,12 +600,51 @@ void ReceiverView::on_packet_tpms(const TPMSPacketMessage& message) {
 		// TODO: function doesn't take uint64_t, so when >= 1<<32, weirdness will ensue!
 		const auto tuning_frequency_str = to_string_dec_uint(tuning_frequency, 10);
 
-		std::string log = timestamp + " " + tuning_frequency_str + " FSK 38.4 19.2 " + hex_data + "/" + hex_error + "\r\n";
+		std::string log = timestamp + " " + tuning_frequency_str + " FSK 38.4 19.2 " + hex_formatted.first + "/" + hex_formatted.second + "\r\n";
 		f_puts(log.c_str(), &fil_tpms);
 		f_sync(&fil_tpms);
 	}
 }
 
+static std::bitset<512> manchester_decode(
+	const size_t sense,
+	const std::bitset<1024>& encoded,
+	const size_t count
+) {
+	std::bitset<512> result;
+	for(size_t i=0; i<count; i+=2) {
+		result[i >> 1] = encoded[i+sense];
+	}
+	return result;
+}
+
+static std::bitset<512> manchester_errors(
+	const std::bitset<1024>& encoded,
+	const size_t count
+) {
+	std::bitset<512> result;
+	for(size_t i=0; i<count; i+=2) {
+		result[i >> 1] = (encoded[i+0] == encoded[i+1]);
+	}
+	return result;
+}
+
+void ReceiverView::on_packet_ert(const ERTPacketMessage& message) {
+	auto console = reinterpret_cast<Console*>(widget_content.get());
+
+	if( message.packet.preamble == 0x555516a3 ) {
+		console->writeln("IDM");
+	}
+	if( message.packet.preamble == 0x1f2a60 ) {
+		console->writeln("SCM");
+		const auto decoded = manchester_decode(0, message.packet.payload, message.packet.bits_received);
+	}
+
+	const auto hex_formatted = format_manchester(0, message.packet.payload, message.packet.bits_received);
+	console->writeln(hex_formatted.first);
+	console->writeln(hex_formatted.second);
+}
+
 void ReceiverView::on_sd_card_status(const sd_card::Status status) {
 	if( status == sd_card::Status::Mounted ) {
 		const auto open_result = f_open(&fil_tpms, "tpms.txt", FA_WRITE | FA_OPEN_ALWAYS);
@@ -642,6 +702,15 @@ void ReceiverView::on_modulation_changed(int32_t modulation) {
 		receiver_model.set_baseband_bandwidth(1750000);
 		break;
 
+	case 6:
+		receiver_model.set_baseband_configuration({
+			.mode = modulation,
+			.sampling_rate = 4194304,
+			.decimation_factor = 1,
+		});
+		receiver_model.set_baseband_bandwidth(1750000);
+		break;
+
 	case 4:
 		receiver_model.set_baseband_configuration({
 			.mode = modulation,
@@ -667,6 +736,7 @@ void ReceiverView::on_modulation_changed(int32_t modulation) {
 	switch(modulation) {
 	case 3:
 	case 5:
+	case 6:
 		widget_content = std::make_unique<Console>();
 		add_child(widget_content.get());
 		break;

firmware/application/ui_receiver.hpp

@@ -417,6 +417,7 @@ private:
 			{ "WFM ", 2 },
 			{ "AIS ", 3 },
 			{ "TPMS", 5 },
+			{ "ERT",  6 },
 			{ "SPEC", 4 },
 		}
 	};
@@ -475,6 +476,7 @@ private:
 
 	void on_packet_ais(const AISPacketMessage& message);
 	void on_packet_tpms(const TPMSPacketMessage& message);
+	void on_packet_ert(const ERTPacketMessage& message);
 	void on_sd_card_status(const sd_card::Status status);
 
 	SignalToken sd_card_status_signal_token;

firmware/baseband/Makefile

@@ -140,6 +140,7 @@ CPPSRC = main.cpp \
          proc_ais.cpp \
          proc_wideband_spectrum.cpp \
          proc_tpms.cpp \
+         proc_ert.cpp \
          dsp_squelch.cpp \
          clock_recovery.cpp \
          packet_builder.cpp \

firmware/baseband/main.cpp

@@ -58,6 +58,7 @@
 #include "proc_ais.hpp"
 #include "proc_wideband_spectrum.hpp"
 #include "proc_tpms.hpp"
+#include "proc_ert.hpp"
 
 #include "clock_recovery.hpp"
 #include "packet_builder.hpp"
@@ -370,6 +371,10 @@ int main(void) {
 					baseband_thread.baseband_processor = new TPMSProcessor();
 					break;
 
+				case 6:
+					baseband_thread.baseband_processor = new ERTProcessor();
+					break;
+
 				default:
 					break;
 				}

firmware/baseband/proc_ert.cpp

@@ -0,0 +1,117 @@
+/*
+ * Copyright (C) 2015 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_ert.hpp"
+
+#include "portapack_shared_memory.hpp"
+
+#include "i2s.hpp"
+using namespace lpc43xx;
+
+float ERTProcessor::abs(const complex8_t& v) {
+	// const int16_t r = v.real() - offset_i;
+	// const int16_t i = v.imag() - offset_q;
+	// const uint32_t r2 = r * r;
+	// const uint32_t i2 = i * i;
+	// const uint32_t r2_i2 = r2 + i2;
+	// return std::sqrt(static_cast<float>(r2_i2));
+	const float r = static_cast<float>(v.real()) - offset_i;
+	const float i = static_cast<float>(v.imag()) - offset_q;
+	const float r2 = r * r;
+	const float i2 = i * i;
+	const float r2_i2 = r2 + i2;
+	return std::sqrt(r2_i2);
+}
+
+void ERTProcessor::execute(buffer_c8_t buffer) {
+	/* 4.194304MHz, 2048 samples */
+	// auto decimator_out = decimator.execute(buffer);
+
+	const complex8_t* src = &buffer.p[0];
+	const complex8_t* const src_end = &buffer.p[buffer.count];
+
+	average_i += src->real();
+	average_q += src->imag();
+	average_count++;
+	if( average_count == 2048 ) {
+		offset_i = static_cast<float>(average_i) / 2048.0f;
+		offset_q = static_cast<float>(average_q) / 2048.0f;
+		average_i = 0;
+		average_q = 0;
+		average_count = 0;
+	}
+
+	const float gain = 128 * samples_per_symbol;
+	const float k = 1.0f / gain;
+
+	while(src < src_end) {
+		float sum = 0.0f;
+		for(size_t i=0; i<(samples_per_symbol / 2); i++) {
+			sum += abs(*(src++));
+		}
+		sum_half_period[1] = sum_half_period[0];
+		sum_half_period[0] = sum;
+
+		sum_period[2] = sum_period[1];
+		sum_period[1] = sum_period[0];
+		sum_period[0] = (sum_half_period[0] + sum_half_period[1]) * k;
+
+		manchester[2] = manchester[1];
+		manchester[1] = manchester[0];
+		manchester[0] = sum_period[2] - sum_period[0];
+
+		const auto data = manchester[0] - manchester[2];
+
+		clock_recovery(data);
+	}
+
+	i2s::i2s0::tx_mute();
+}
+
+void ERTProcessor::consume_symbol(
+	const float raw_symbol
+) {
+	const uint_fast8_t sliced_symbol = (raw_symbol >= 0.0f) ? 1 : 0;
+	scm_builder.execute(sliced_symbol);
+	idm_builder.execute(sliced_symbol);
+}
+
+void ERTProcessor::scm_handler(
+	const std::bitset<1024>& payload,
+	const size_t bits_received
+) {
+	ERTPacketMessage message;
+	message.packet.preamble = 0x1f2a60;
+	message.packet.payload = payload;
+	message.packet.bits_received = bits_received;
+	shared_memory.application_queue.push(message);
+}
+
+void ERTProcessor::idm_handler(
+	const std::bitset<1024>& payload,
+	const size_t bits_received
+) {
+	ERTPacketMessage message;
+	message.packet.preamble = 0x555516a3;
+	message.packet.payload = payload;
+	message.packet.bits_received = bits_received;
+	shared_memory.application_queue.push(message);
+}

firmware/baseband/proc_ert.hpp

@@ -0,0 +1,108 @@
+/*
+ * Copyright (C) 2015 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.
+ */
+
+#ifndef __PROC_ERT_H__
+#define __PROC_ERT_H__
+
+#include "baseband_processor.hpp"
+
+#include "channel_decimator.hpp"
+
+#include "clock_recovery.hpp"
+#include "symbol_coding.hpp"
+#include "packet_builder.hpp"
+
+#include "message.hpp"
+
+#include <cstdint>
+#include <cstddef>
+#include <bitset>
+
+// ''.join(['%d%d' % (c, 1-c) for c in map(int, bin(0x1f2a60)[2:].zfill(21))])
+constexpr uint64_t scm_preamble_and_sync_manchester { 0b101010101001011001100110010110100101010101 };
+constexpr size_t scm_preamble_and_sync_length { 42 - 10 };
+constexpr size_t scm_payload_length_max { 150 };
+
+// ''.join(['%d%d' % (c, 1-c) for c in map(int, bin(0x555516a3)[2:].zfill(32))])
+constexpr uint64_t idm_preamble_and_sync_manchester { 0b0110011001100110011001100110011001010110011010011001100101011010 };
+constexpr size_t idm_preamble_and_sync_length { 64 - 16 };
+
+// TODO: Should be 1408, but need to widen pathway to application processor...
+constexpr size_t idm_payload_length_max { 960 };
+
+class ERTProcessor : public BasebandProcessor {
+public:
+	using payload_t = std::bitset<1024>;
+
+	void execute(buffer_c8_t buffer) override;
+
+private:
+	const uint32_t baseband_sampling_rate = 4194304;
+	const size_t decimation = 1;
+	const uint32_t symbol_rate = 32768;
+
+	const uint32_t channel_sampling_rate = baseband_sampling_rate / decimation;
+	const size_t samples_per_symbol = channel_sampling_rate / symbol_rate;
+	const uint32_t clock_recovery_rate = symbol_rate * 2;
+
+	// ChannelDecimator decimator { ChannelDecimator::DecimationFactor::By2, false };
+
+	clock_recovery::ClockRecovery<clock_recovery::FixedErrorFilter> clock_recovery {
+		clock_recovery_rate, symbol_rate, { 1.0f / 18.0f },
+		[this](const float symbol) { this->consume_symbol(symbol); }
+	};
+
+	PacketBuilder<BitPattern, NeverMatch, FixedLength> scm_builder {
+		{ scm_preamble_and_sync_manchester, scm_preamble_and_sync_length, 1 },
+		{ },
+		{ scm_payload_length_max },
+		[this](const payload_t& payload, const size_t bits_received) {
+			this->scm_handler(payload, bits_received);
+		}
+	};
+
+	PacketBuilder<BitPattern, NeverMatch, FixedLength> idm_builder {
+		{ idm_preamble_and_sync_manchester, idm_preamble_and_sync_length, 1 },
+		{ },
+		{ idm_payload_length_max },
+		[this](const payload_t& payload, const size_t bits_received) {
+			this->idm_handler(payload, bits_received);
+		}
+	};
+
+	void consume_symbol(const float symbol);
+	void scm_handler(const payload_t& payload, const size_t bits_received);
+	void idm_handler(const payload_t& payload, const size_t bits_received);
+
+	float sum_half_period[2];
+	float sum_period[3];
+	float manchester[3];
+
+	int32_t average_i { 0 };
+	int32_t average_q { 0 };
+	size_t average_count { 0 };
+	float offset_i { 0.0f };
+	float offset_q { 0.0f };
+
+	float abs(const complex8_t& v);
+};
+
+#endif/*__PROC_ERT_H__*/

firmware/common/message.hpp

@@ -46,6 +46,7 @@ public:
 		TPMSPacket = 6,
 		Shutdown = 8,
 		AISPacket = 7,
+		ERTPacket = 9,
 		MAX
 	};
 
@@ -240,6 +241,22 @@ public:
 	}
 };
 
+struct ERTPacket {
+	uint64_t preamble { 0 };
+	std::bitset<1024> payload;
+	size_t bits_received { 0 };
+};
+
+class ERTPacketMessage : public Message {
+public:
+	constexpr ERTPacketMessage(
+	) : Message { ID::ERTPacket }
+	{
+	}
+
+	ERTPacket packet;
+};
+
 class MessageHandlerMap {
 public:
 	using MessageHandler = std::function<void(Message* const p)>;