X-Git-Url: https://git.rvb.name/rtl-433.git/blobdiff_plain/ca13278b24eb61443559bcb61e64627fba3d8823..6d15c6f967221af825cf84e3ed12b96c763b127b:/include/baseband.h

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+/**
+ * Baseband
+ * 
+ * Various functions for baseband sample processing
+ *
+ * Copyright (C) 2012 by Benjamin Larsson <benjamin@southpole.se>
+ * Copyright (C) 2015 Tommy Vestermark
+ * 
+ * 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 of the License, or
+ * (at your option) any later version.
+ */
+
+#ifndef INCLUDE_BASEBAND_H_
+#define INCLUDE_BASEBAND_H_
+
+#include <stdint.h>
+
+/// This will give a noisy envelope of OOK/ASK signals
+
+/// Subtract the bias (-128) and get an envelope estimation (absolute squared)
+/// @param *iq_buf: input samples (I/Q samples in interleaved uint8)
+/// @param *y_buf: output 
+/// @param len: number of samples to process
+void envelope_detect(const uint8_t *iq_buf, uint16_t *y_buf, uint32_t len);
+
+#define FILTER_ORDER 1
+
+/// Filter state buffer
+typedef struct {
+	int16_t	y[FILTER_ORDER];
+	int16_t	x[FILTER_ORDER];
+} FilterState;
+
+/// FM_Demod state buffer
+typedef struct {
+	int16_t	br, bi;		// Last I/Q sample
+	int16_t xlp, ylp;	// Low-pass filter state
+} DemodFM_State;
+
+/// Lowpass filter
+///
+/// Function is stateful
+/// @param *x_buf: input samples to be filtered
+/// @param *y_buf: output from filter
+/// @param len: number of samples to process
+/// @param FilterState: State to store between chunk processing
+void baseband_low_pass_filter(const uint16_t *x_buf, int16_t *y_buf, uint32_t len, FilterState *state);
+
+/// FM demodulator
+///
+/// Function is stateful
+/// @param *x_buf: input samples (I/Q samples in interleaved uint8)
+/// @param *y_buf: output from FM demodulator
+/// @param len: number of samples to process
+/// @param DemodFM_State: State to store between chunk processing
+void baseband_demod_FM(const uint8_t *x_buf, int16_t *y_buf, unsigned num_samples, DemodFM_State *state);
+
+/// Initialize tables and constants
+/// Should be called once at startup
+void baseband_init(void);
+
+/// Dump binary data (for debug purposes)
+void baseband_dumpfile(const uint8_t *buf, uint32_t len);
+
+#endif /* INCLUDE_BASEBAND_H_ */