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FSK: Fix pulse overflow and integer overflow

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Avoids crash when detecting too many FSK pulses.
Frequncy estimaters could overflow when F1 and F2 are too far apart.
This commit is contained in:
Tommy Vestermark
2015-08-29 16:03:13 +02:00
parent f6fc204bbb
commit cfb78dd92a
1 changed files with 10 additions and 5 deletions
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15
src/pulse_detect.c
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@@ -50,8 +50,8 @@ typedef struct {
PD_STATE_FSK_F2 = 1 // Low pulse (gap)
} state_fsk;
int16_t fm_f1_est; // Estimate for the F1 frequency for FSK
int16_t fm_delta_est; // Estimate for the delta |F2-F1| frequency for FSK
int fm_f1_est; // Estimate for the F1 frequency for FSK
int fm_delta_est; // Estimate for the delta |F2-F1| frequency for FSK
} pulse_state_t;
static pulse_state_t pulse_state;
@@ -106,9 +106,9 @@ int detect_pulse_package(const int16_t *envelope_data, const int16_t *fm_data, u
}
} else {
// FSK Demodulation
int16_t fm_n = fm_data[s->data_counter]; // Get current FM sample
int16_t fm_delta = abs(fm_n - s->fm_f1_est); // Get delta from base frequency estimate
int16_t fm_hyst = (s->fm_delta_est/2) / 8; // ±12% hysteresis on threshold
int fm_n = fm_data[s->data_counter]; // Get current FM sample
int fm_delta = abs(fm_n - s->fm_f1_est); // Get delta from base frequency estimate
int fm_hyst = (s->fm_delta_est/2) / 8; // ±12% hysteresis on threshold
switch(s->state_fsk) {
case PD_STATE_FSK_F1: // Pulse high at initial frequency
// Initial samples in OOK pulse?
@@ -131,6 +131,11 @@ int detect_pulse_package(const int16_t *envelope_data, const int16_t *fm_data, u
fsk_pulses->num_pulses++;
s->fsk_pulse_length = 0;
s->state_fsk = PD_STATE_FSK_F1;
// EOP if too many pulses
if (fsk_pulses->num_pulses >= PD_MAX_PULSES) {
s->state = PD_STATE_IDLE;
return 2; // FSK: End Of Package!!
}
// Still above threshold
} else {
s->fm_delta_est = s->fm_delta_est - s->fm_delta_est/FSK_EST_RATIO + fm_delta/FSK_EST_RATIO; // Slow estimator