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CHG: some average / mean functions to enhance justNoise functions.

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FIX: 'lf t55xx' - verifying that collected signal is not just noise..
This commit is contained in:
iceman1001 2017-10-30 16:44:04 +01:00
commit 6f948be842
5 changed files with 105 additions and 55 deletions
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68
common/lfdemod.c
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@ -60,26 +60,62 @@ void dummy(char *fmt, ...){}
# define prnt dummy
#endif
//test samples are not just noise
uint8_t justNoise(uint8_t *bits, size_t size) {
// Function to compute mean for a series
// rounded to integer..
uint32_t compute_mean_uint(uint8_t *in, size_t N) {
uint32_t mean = 0;
for (size_t i = 0; i < N; i++)
mean += in[i];
return (uint32_t)mean/N;
}
// Function to compute mean for a series
// rounded to integer..
int32_t compute_mean_int(int *in, size_t N) {
int32_t mean = 0;
for (size_t i = 0; i < N; i++)
mean += in[i];
return (int32_t)mean/N;
}
//test samples are not just noise
bool justNoise(uint8_t *bits, size_t size) {
// if we take the mean on the sample set and see if its
// below the threshold, it will be a better indicator
uint32_t mean = compute_mean_uint(bits, size);
uint8_t counter = 0;
for ( size_t i = 0; i < size && counter < 10; i++) {
if ( bits[i] > mean ) counter++;
}
if (g_debugMode == 2) prnt("DEBUG: (justNoise) mean %u | %i | counter %u", mean, FSK_PSK_THRESHOLD, counter);
return counter < 10;
/*
// loop until a sample is larger than threshold.
// one sample above threshold is not a good indicator.
uint8_t val = 1;
for(size_t idx = 0; idx < size && val; idx++)
val = bits[idx] < FSK_PSK_THRESHOLD;
return val;
*/
}
//by marshmellow
//get high and low values of a wave with passed in fuzz factor. also return noise test = 1 for passed or 0 for only noise
int getHiLo(uint8_t *BitStream, size_t size, int *high, int *low, uint8_t fuzzHi, uint8_t fuzzLo) {
*high=0;
*low=255;
int getHiLo(uint8_t *bits, size_t size, int *high, int *low, uint8_t fuzzHi, uint8_t fuzzLo) {
*high = 0; *low = 255;
// get high and low thresholds
for (size_t i=0; i < size; i++){
if (BitStream[i] > *high) *high = BitStream[i];
if (BitStream[i] < *low) *low = BitStream[i];
if (bits[i] > *high) *high = bits[i];
if (bits[i] < *low) *low = bits[i];
}
if (*high < FSK_PSK_THRESHOLD) return -1; // just noise
// just noise - no super good detection. good enough
if (*high < FSK_PSK_THRESHOLD) return -1;
// add fuzz.
*high = ((*high-128)*fuzzHi + 12800)/100;
*low = ((*low-128)*fuzzLo + 12800)/100;
return 1;
@ -203,18 +239,18 @@ bool preambleSearchEx(uint8_t *BitStream, uint8_t *preamble, size_t pLen, size_t
}
// find start of modulating data (for fsk and psk) in case of beginning noise or slow chip startup.
size_t findModStart(uint8_t dest[], size_t size, uint8_t expWaveSize) {
size_t findModStart(uint8_t *src, size_t size, uint8_t expWaveSize) {
size_t i = 0;
size_t waveSizeCnt = 0;
uint8_t thresholdCnt = 0;
bool isAboveThreshold = dest[i++] >= FSK_PSK_THRESHOLD;
bool isAboveThreshold = src[i++] >= FSK_PSK_THRESHOLD;
for (; i < size-20; i++ ) {
if(dest[i] < FSK_PSK_THRESHOLD && isAboveThreshold) {
if(src[i] < FSK_PSK_THRESHOLD && isAboveThreshold) {
thresholdCnt++;
if (thresholdCnt > 2 && waveSizeCnt < expWaveSize+1) break;
isAboveThreshold = false;
waveSizeCnt = 0;
} else if (dest[i] >= FSK_PSK_THRESHOLD && !isAboveThreshold) {
} else if (src[i] >= FSK_PSK_THRESHOLD && !isAboveThreshold) {
thresholdCnt++;
if (thresholdCnt > 2 && waveSizeCnt < expWaveSize+1) break;
isAboveThreshold = true;
@ -224,7 +260,7 @@ size_t findModStart(uint8_t dest[], size_t size, uint8_t expWaveSize) {
}
if (thresholdCnt > 10) break;
}
if (g_debugMode == 2) prnt("DEBUG: threshold Count reached at %u, count: %u",i, thresholdCnt);
if (g_debugMode == 2) prnt("DEBUG: threshold Count reached at %u, count: %u", i, thresholdCnt);
return i;
}
@ -1441,7 +1477,7 @@ size_t fsk_wave_demod(uint8_t * dest, size_t size, uint8_t fchigh, uint8_t fclow
size_t last_transition = 0;
size_t idx = 1;
//find start of modulating data in trace
//find start of modulating data in trace
idx = findModStart(dest, size, fchigh);
// Need to threshold first sample
if(dest[idx] < FSK_PSK_THRESHOLD) dest[0] = 0;
@ -1769,8 +1805,8 @@ int HIDdemodFSK(uint8_t *dest, size_t *size, uint32_t *hi2, uint32_t *hi, uint32
if (dest[idx] == dest[idx+1]){
return -5; //not manchester data
}
*hi2 = (*hi2<<1)|(*hi>>31);
*hi = (*hi<<1)|(*lo>>31);
*hi2 = (*hi2 << 1) | (*hi >> 31);
*hi = (*hi << 1) | (*lo >> 31);
//Then, shift in a 0 or one into low
*lo <<= 1;
if (dest[idx] && !dest[idx+1]) // 1 0