ADS-B TX works well enough for dump1090 and gr-air-modes

Hooked ADS-B RX to baseband instead of debug IQ file, not tested

firmware/baseband/proc_adsbrx.hpp

@@ -0,0 +1,62 @@
+/*
+ * Copyright (C) 2014 Jared Boone, ShareBrained Technology, Inc.
+ * Copyright (C) 2017 Furrtek
+ *
+ * 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_ADSBRX_H__
+#define __PROC_ADSBRX_H__
+
+#include "baseband_processor.hpp"
+#include "baseband_thread.hpp"
+
+#include "adsb_frame.hpp"
+
+using namespace adsb;
+
+#define ADSB_PREAMBLE_LENGTH 16
+
+class ADSBRXProcessor : public BasebandProcessor {
+public:
+	void execute(const buffer_c8_t& buffer) override;
+	
+	void on_message(const Message* const message) override;
+
+private:
+	static constexpr float k = 1.0f / 128.0f;
+	
+	static constexpr size_t baseband_fs = 2000000;
+	
+	BasebandThread baseband_thread { baseband_fs, this, NORMALPRIO + 20, baseband::Direction::Receive };
+	
+	ADSBFrame frame { };
+	bool configured { false };
+	float prev_mag { 0 };
+	float threshold, threshold_low, threshold_high;
+	size_t null_count, bit_count, sample_count;
+	std::pair<float, uint8_t> shifter[ADSB_PREAMBLE_LENGTH];
+	bool decoding { };
+	bool preamble { }, active { };
+    uint16_t bit_pos { 0 };
+    uint8_t cur_bit { 0 };
+	uint32_t sample { 0 };
+	int8_t re { }, im { };
+};
+
+#endif