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/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__*/