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77 lines
2.6 KiB
C
77 lines
2.6 KiB
C
/** @file
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Various functions for baseband sample processing.
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Copyright (C) 2012 by Benjamin Larsson <benjamin@southpole.se>
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Copyright (C) 2015 Tommy Vestermark
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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*/
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#ifndef INCLUDE_BASEBAND_H_
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#define INCLUDE_BASEBAND_H_
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#include <stdint.h>
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/** This will give a noisy envelope of OOK/ASK signals.
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Subtract the bias (-128) and get an envelope estimation (absolute squared)
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@param iq_buf: input samples (I/Q samples in interleaved uint8)
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@param[out] y_buf: output
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@param len: number of samples to process
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*/
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void envelope_detect(uint8_t const *iq_buf, uint16_t *y_buf, uint32_t len);
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// for evaluation
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void envelope_detect_nolut(uint8_t const *iq_buf, uint16_t *y_buf, uint32_t len);
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void magnitude_est_cu8(uint8_t const *iq_buf, uint16_t *y_buf, uint32_t len);
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void magnitude_true_cu8(uint8_t const *iq_buf, uint16_t *y_buf, uint32_t len);
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void magnitude_est_cs16(int16_t const *iq_buf, uint16_t *y_buf, uint32_t len);
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void magnitude_true_cs16(int16_t const *iq_buf, uint16_t *y_buf, uint32_t len);
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#define FILTER_ORDER 1
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/// Filter state buffer.
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typedef struct filter_state {
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int16_t y[FILTER_ORDER];
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int16_t x[FILTER_ORDER];
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} filter_state_t;
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/// FM_Demod state buffer.
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typedef struct demodfm_state {
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int32_t br, bi; // Last I/Q sample
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int32_t xlp, ylp; // Low-pass filter state
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} demodfm_state_t;
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/** Lowpass filter.
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Function is stateful
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@param x_buf: input samples to be filtered
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@param[out] y_buf: output from filter
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@param len: number of samples to process
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@param[in,out] state: State to store between chunk processing
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*/
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void baseband_low_pass_filter(uint16_t const *x_buf, int16_t *y_buf, uint32_t len, filter_state_t *state);
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/** FM demodulator.
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Function is stateful
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@param x_buf: input samples (I/Q samples in interleaved uint8)
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@param[out] y_buf: output from FM demodulator
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@param len: number of samples to process
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@param[in,out] state: State to store between chunk processing
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*/
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void baseband_demod_FM(uint8_t const *x_buf, int16_t *y_buf, unsigned long num_samples, demodfm_state_t *state);
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/// For evaluation.
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void baseband_demod_FM_cs16(int16_t const *x_buf, int16_t *y_buf, unsigned long num_samples, demodfm_state_t *state);
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/** Initialize tables and constants.
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Should be called once at startup.
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*/
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void baseband_init(void);
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#endif /* INCLUDE_BASEBAND_H_ */
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