Rename the parameter "coherent" to "FFSK" which is the correct meaning.
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libfsk/fsk.c
22
libfsk/fsk.c
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@ -1,4 +1,4 @@
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/* FSK audio processing (coherent FSK modem)
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/* FSK audio processing (FSK/FFSK modem)
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*
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* (C) 2017 by Andreas Eversberg <jolly@eversberg.eu>
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* All Rights Reserved
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@ -37,9 +37,9 @@
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* bitrate = bits per second
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* f0, f1 = two frequencies for bit 0 and bit 1
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* level = level to modulate the frequencies
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* coherent = use coherent modulation (FFSK)
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* ffsk = use FFSK modulation (each symbol ends at zero crossing)
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*/
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int fsk_mod_init(fsk_mod_t *fsk, void *inst, int (*send_bit)(void *inst), int samplerate, double bitrate, double f0, double f1, double level, int coherent, int filter)
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int fsk_mod_init(fsk_mod_t *fsk, void *inst, int (*send_bit)(void *inst), int samplerate, double bitrate, double f0, double f1, double level, int ffsk, int filter)
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{
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int i;
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int rc;
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@ -80,23 +80,23 @@ int fsk_mod_init(fsk_mod_t *fsk, void *inst, int (*send_bit)(void *inst), int sa
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fsk->phaseshift65536[1] = f1 / (double)samplerate * 65536.0;
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PDEBUG(DDSP, DEBUG_DEBUG, "F1 = %.0f Hz (phaseshift65536[1] = %.4f)\n", f1, fsk->phaseshift65536[1]);
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/* use coherent modulation, i.e. each bit has an integer number of
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/* use ffsk modulation, i.e. each bit has an integer number of
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* half waves and starts/ends at zero crossing
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*/
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if (coherent) {
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if (ffsk) {
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double waves;
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PDEBUG(DDSP, DEBUG_DEBUG, "enable coherent FSK modulation mode\n");
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fsk->coherent = 1;
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PDEBUG(DDSP, DEBUG_DEBUG, "enable FFSK modulation mode\n");
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fsk->ffsk = 1;
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waves = (f0 / bitrate);
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if (fabs(round(waves * 2) - (waves * 2)) > 0.001) {
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fprintf(stderr, "Failed to set coherent mode, half waves of F0 does not fit exactly into one bit, please fix!\n");
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fprintf(stderr, "Failed to set FFSK mode, half waves of F0 does not fit exactly into one bit, please fix!\n");
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abort();
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}
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fsk->cycles_per_bit65536[0] = waves * 65536.0;
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waves = (f1 / bitrate);
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if (fabs(round(waves * 2) - (waves * 2)) > 0.001) {
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fprintf(stderr, "Failed to set coherent mode, half waves of F1 does not fit exactly into one bit, please fix!\n");
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fprintf(stderr, "Failed to set FFSK mode, half waves of F1 does not fit exactly into one bit, please fix!\n");
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abort();
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}
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fsk->cycles_per_bit65536[1] = waves * 65536.0;
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@ -141,7 +141,7 @@ void fsk_mod_cleanup(fsk_mod_t *fsk)
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* return -1. In this case, this function stops and returns the number of
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* samples that have been rendered so far, if any.
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*
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* For coherent mode (FSK), we round the phase on every bit change to the
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* For FFSK mode, we round the phase on every bit change to the
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* next zero crossing. This prevents phase shifts due to rounding errors.
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*/
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int fsk_mod_send(fsk_mod_t *fsk, sample_t *sample, int length, int add)
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@ -161,7 +161,7 @@ next_bit:
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if (fsk->tx_bit < 0)
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goto done;
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/* correct phase when changing bit */
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if (fsk->coherent) {
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if (fsk->ffsk) {
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/* round phase to nearest zero crossing */
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if (phase > 16384.0 && phase < 49152.0)
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phase = 32768.0;
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@ -9,7 +9,7 @@ typedef struct fsk_mod {
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double cycles_per_bit65536[2]; /* cycles of one bit */
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double tx_phase65536; /* current transmit phase */
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double level; /* level (amplitude) of signal */
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int coherent; /* set, if coherent TX mode */
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int ffsk; /* set, if FFSK TX mode */
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double f0_deviation; /* deviation of frequencies, relative to center */
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double f1_deviation;
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int low_bit, high_bit; /* a low or high deviation means which bit? */
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