45 lines
1.8 KiB
C
45 lines
1.8 KiB
C
#ifndef _LIB_FM_H
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#define _LIB_FM_H
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#include "../libfilter/iir_filter.h"
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int fm_init(int fast_math);
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void fm_exit(void);
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enum fm_mod_state {
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MOD_STATE_OFF, /* transmitter off, no IQ vector */
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MOD_STATE_ON, /* transmitter on, FM modulated IQ vector */
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MOD_STATE_RAMP_UP, /* use half cos to ramp up IQ vector */
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MOD_STATE_RAMP_DOWN, /* use half cos to ramp down IQ vector */
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};
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typedef struct fm_mod {
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double samplerate; /* sample rate of in and out */
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double offset; /* offset to calculated center frequency */
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double amplitude; /* how much amplitude to add to the buff */
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double phase; /* current phase of FM (used to shift and modulate ) */
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enum fm_mod_state state;/* state of transmit power */
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double *ramp_tab; /* half cosine ramp up */
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int ramp; /* current ramp position */
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int ramp_length; /* number of values in ramp */
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} fm_mod_t;
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int fm_mod_init(fm_mod_t *mod, double samplerate, double offset, double amplitude);
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void fm_mod_exit(fm_mod_t *mod);
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void fm_modulate_complex(fm_mod_t *mod, sample_t *frequency, uint8_t *power, int num, float *baseband);
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typedef struct fm_demod {
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double samplerate; /* sample rate of in and out */
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double phase; /* current rotation phase (used to shift) */
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double rot; /* rotation step per sample to shift rx frequency (used to shift) */
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double last_phase; /* last phase of FM (used to demodulate) */
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iir_filter_t lp[2]; /* filters received IQ signal */
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} fm_demod_t;
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int fm_demod_init(fm_demod_t *demod, double samplerate, double offset, double bandwidth);
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void fm_demod_exit(fm_demod_t *demod);
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void fm_demodulate_complex(fm_demod_t *demod, sample_t *frequency, int length, float *baseband, sample_t *I, sample_t *Q);
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void fm_demodulate_real(fm_demod_t *demod, sample_t *frequency, int length, sample_t *baseband, sample_t *I, sample_t *Q);
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#endif /* _LIB_FM_H */
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