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Fix issue #118 for better FSK on saturated signals

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This commit is contained in:
Philippe Teuwen 2019-03-07 21:13:58 +01:00
commit 1f0c1dff5e
1 changed files with 17 additions and 10 deletions
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27
common/lfdemod.c
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@ -106,16 +106,23 @@ int32_t compute_mean_int(int *in, size_t N) {
} }
void zeromean(uint8_t* data, size_t size) { void zeromean(uint8_t* data, size_t size) {
// zero mean data // zero mean data
int i, accum = 0; int i, accum = 0;
for (i = 10; i < size; ++i) for (i = 10; i < size; ++i)
accum += data[i]; accum += data[i] - 128;
accum /= (int)(size - 10);
accum /= (size - 10);
for (i = 0; i < size; ++i) {
for (i = 0; i < size; ++i) if (accum > 0) {
data[i] -= accum; data[i] = (data[i] >= accum)? data[i] - accum : 0;
}
if (accum < 0) {
data[i] = (255 - data[i] >= -accum)? data[i] - accum : 255;
}
}
// recompute signal characteristics:
isNoise(data, size);
} }
//test samples are not just noise //test samples are not just noise
@ -1668,11 +1675,11 @@ size_t fsk_wave_demod(uint8_t *dest, size_t size, uint8_t fchigh, uint8_t fclow,
size_t last_transition = 0; size_t last_transition = 0;
size_t idx = 1; size_t idx = 1;
size_t numBits = 0; size_t numBits = 0;
//find start of modulating data in trace //find start of modulating data in trace
idx = findModStart(dest, size, fchigh); idx = findModStart(dest, size, fchigh);
// Need to threshold first sample // Need to threshold first sample
dest[0] = (dest[idx] < signalprop.mean) ? 0 : 1; dest[idx] = (dest[idx] < signalprop.mean) ? 0 : 1;
last_transition = idx; last_transition = idx;
idx++; idx++;
@ -2119,4 +2126,4 @@ int detectIOProx(uint8_t *dest, size_t *size, int *waveStartIdx) {
return (int) start_idx; return (int) start_idx;
} }
return -6; return -6;
} }