Add TPMS initial demodulator implementation.

Right now, 2FSK, 19200 baud, +/-38400Hz deviation. No effort is made to check CRC/checksums or decode packets.

firmware/baseband/proc_tpms.hpp

@@ -0,0 +1,91 @@
+/*
+ * 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_TPMS_H__
+#define __PROC_TPMS_H__
+
+#include "baseband_processor.hpp"
+
+#include "channel_decimator.hpp"
+#include "matched_filter.hpp"
+
+#include "clock_recovery.hpp"
+#include "symbol_coding.hpp"
+#include "packet_builder.hpp"
+
+#include "message.hpp"
+
+#include <cstdint>
+#include <cstddef>
+#include <bitset>
+
+struct NeverMatch {
+	bool operator()(const BitHistory&, const size_t) const {
+		return false;
+	}
+};
+
+struct FixedLength {
+	bool operator()(const BitHistory&, const size_t symbols_received) const {
+		return symbols_received >= length;
+	}
+
+	const size_t length;
+};
+
+// Translate+rectangular filter
+// sample=153.6k, deviation=38400, symbol=19200
+// Length: 8 taps, 1 symbols, 2 cycles of sinusoid
+constexpr std::array<std::complex<float>, 8> rect_taps_153k6_1t_p { {
+	{  1.2500000000e-01f,  0.0000000000e+00f }, {  7.6540424947e-18f,  1.2500000000e-01f },
+	{ -1.2500000000e-01f,  1.5308084989e-17f }, { -2.2962127484e-17f, -1.2500000000e-01f },
+	{  1.2500000000e-01f, -3.0616169979e-17f }, {  3.8270212473e-17f,  1.2500000000e-01f },
+	{ -1.2500000000e-01f,  4.5924254968e-17f }, { -5.3578297463e-17f, -1.2500000000e-01f },
+} };
+
+class TPMSProcessor : public BasebandProcessor {
+public:
+	using payload_t = std::bitset<1024>;
+
+	void execute(buffer_c8_t buffer) override;
+
+private:
+	ChannelDecimator decimator { ChannelDecimator::DecimationFactor::By16 };
+	dsp::matched_filter::MatchedFilter mf { rect_taps_153k6_1t_p, 4 };
+
+	clock_recovery::ClockRecovery<clock_recovery::FixedErrorFilter> clock_recovery {
+		38400, 19200, { 0.0555f },
+		[this](const float symbol) { this->consume_symbol(symbol); }
+	};
+	PacketBuilder<BitPattern, NeverMatch, FixedLength> packet_builder {
+		{ 0b010101010101010101010101010110, 30, 1 },
+		{ },
+		{ 256 },
+		[this](const payload_t& payload, const size_t bits_received) {
+			this->payload_handler(payload, bits_received);
+		}
+	};
+
+	void consume_symbol(const float symbol);
+	void payload_handler(const payload_t& payload, const size_t bits_received);
+};
+
+#endif/*__PROC_TPMS_H__*/