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rs41mod: home-brewed RS soft decoding w/ erasures v0.2

pull/27/head
Zilog80 2020-06-22 12:08:35 +02:00
rodzic 9b622463a9
commit 873189c573
1 zmienionych plików z 62 dodań i 53 usunięć
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demod/mod/rs41mod.c
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@ -73,6 +73,18 @@ static rscfg_t cfg_rs41 = { 41, (320-56)/2, 56, 8, 8, 320}; // const: msgpos, pa
ui8_t //xframe[FRAME_LEN] = { 0x10, 0xB6, 0xCA, 0x11, 0x22, 0x96, 0x12, 0xF8}, = xorbyte( frame) ui8_t //xframe[FRAME_LEN] = { 0x10, 0xB6, 0xCA, 0x11, 0x22, 0x96, 0x12, 0xF8}, = xorbyte( frame)
frame[FRAME_LEN] = { 0x86, 0x35, 0xf4, 0x40, 0x93, 0xdf, 0x1a, 0x60}; // = xorbyte(xframe) frame[FRAME_LEN] = { 0x86, 0x35, 0xf4, 0x40, 0x93, 0xdf, 0x1a, 0x60}; // = xorbyte(xframe)
*/ */
typedef struct {
float frm_bytescore[FRAME_LEN+8];
float ts;
float last_frnb_ts;
float last_calfrm_ts;
ui16_t last_frnb;
ui8_t last_calfrm;
int sort_idx1[FRAME_LEN]; // ui8_t[] sort_cw1_idx
int sort_idx2[FRAME_LEN]; // ui8_t[] sort_cw2_idx
} ecdat_t;
typedef struct { typedef struct {
int out; int out;
int frnr; int frnr;
@ -109,6 +121,7 @@ typedef struct {
char xdata[XDATA_LEN+16]; // xdata: aux_str1#aux_str2 ... char xdata[XDATA_LEN+16]; // xdata: aux_str1#aux_str2 ...
option_t option; option_t option;
RS_t RS; RS_t RS;
ecdat_t ecdat;
} gpx_t; } gpx_t;
@ -139,19 +152,6 @@ static ui8_t mask[MASK_LEN] = { 0x96, 0x83, 0x3E, 0x51, 0xB1, 0x49, 0x08, 0x98,
frame[pos] = xframe[pos] ^ mask[pos % MASK_LEN]; frame[pos] = xframe[pos] ^ mask[pos % MASK_LEN];
*/ */
typedef struct {
float frm_softbits[FRAME_LEN*BITS+64];
float ts;
float last_frnb_ts;
float last_calfrm_ts;
ui16_t last_frnb;
ui8_t last_calfrm;
} ecdat_t;
static ecdat_t ecdat;
static int sort_idx1[FRAME_LEN]; // ui8_t[] codeword
static int sort_idx2[FRAME_LEN];
/* ------------------------------------------------------------------------------------ */ /* ------------------------------------------------------------------------------------ */
#define BAUD_RATE 4800 #define BAUD_RATE 4800
@ -378,8 +378,8 @@ static int get_FrameNb(gpx_t *gpx, int crc, int ofs) {
// crc check // crc check
if (crc == 0) { if (crc == 0) {
ecdat.last_frnb = frnr; gpx->ecdat.last_frnb = frnr;
ecdat.last_frnb_ts = ecdat.ts; gpx->ecdat.last_frnb_ts = gpx->ecdat.ts;
} }
return 0; return 0;
@ -432,7 +432,7 @@ static int get_SondeID(gpx_t *gpx, int crc, int ofs) {
memcpy(gpx->id, sondeid_bytes, 8); memcpy(gpx->id, sondeid_bytes, 8);
gpx->id[8] = '\0'; gpx->id[8] = '\0';
ecdat.last_frnb = 0; gpx->ecdat.last_frnb = 0;
} }
} }
@ -462,8 +462,8 @@ static int get_FrameConf(gpx_t *gpx, int ofs) {
gpx->calfrchk[calfr] = 1; gpx->calfrchk[calfr] = 1;
} }
ecdat.last_calfrm = calfr; gpx->ecdat.last_calfrm = calfr;
ecdat.last_calfrm_ts = ecdat.ts; gpx->ecdat.last_calfrm_ts = gpx->ecdat.ts;
} }
return err; return err;
@ -1112,10 +1112,10 @@ static int rs41_ecc(gpx_t *gpx, int frmlen) {
if (gpx->option.ecc > 3) // set (probably) known bytes (if same rs41) if (gpx->option.ecc > 3) // set (probably) known bytes (if same rs41)
{ {
float frnb_ts = ecdat.ts - ecdat.last_frnb_ts + 0.5f; float frnb_ts = gpx->ecdat.ts - gpx->ecdat.last_frnb_ts + 0.5f;
int frnb = ecdat.last_frnb + (unsigned)frnb_ts; int frnb = gpx->ecdat.last_frnb + (unsigned)frnb_ts;
float calfr_ts = ecdat.ts - ecdat.last_calfrm_ts + 0.5f; float calfr_ts = gpx->ecdat.ts - gpx->ecdat.last_calfrm_ts + 0.5f;
int calfr = (ecdat.last_calfrm + (unsigned)calfr_ts) % 51; int calfr = (gpx->ecdat.last_calfrm + (unsigned)calfr_ts) % 51;
if (errors1 < 0) { if (errors1 < 0) {
// chkCRC // chkCRC
@ -1145,7 +1145,7 @@ static int rs41_ecc(gpx_t *gpx, int frmlen) {
//pos_FrameNb: 0x03B=59 //pos_FrameNb: 0x03B=59
if (crc && ((frnb>>8)&0xFF) != gpx->frame[pos_FrameNb+1]) { if (crc && ((frnb>>8)&0xFF) != gpx->frame[pos_FrameNb+1]) {
// last valid check, last_frnb>0 ... // last valid check, last_frnb>0 ...
if (ecdat.last_frnb > 0) gpx->frame[pos_FrameNb+1] = (frnb>>8)&0xFF; if (gpx->ecdat.last_frnb > 0) gpx->frame[pos_FrameNb+1] = (frnb>>8)&0xFF;
} }
} }
@ -1174,7 +1174,7 @@ static int rs41_ecc(gpx_t *gpx, int frmlen) {
//pos_FrameNb: 0x03B=59 //pos_FrameNb: 0x03B=59
if (crc && (frnb&0xFF) != gpx->frame[pos_FrameNb]) { if (crc && (frnb&0xFF) != gpx->frame[pos_FrameNb]) {
// last valid check, last_frnb>0 ... // last valid check, last_frnb>0 ...
if (ecdat.last_frnb > 0) gpx->frame[pos_FrameNb] = frnb&0xFF; if (gpx->ecdat.last_frnb > 0) gpx->frame[pos_FrameNb] = frnb&0xFF;
} }
} }
@ -1187,6 +1187,7 @@ static int rs41_ecc(gpx_t *gpx, int frmlen) {
// 3rd pass: // 3rd pass:
// 2 RS codewords interleaved: 2x12 errors can be corrected; // 2 RS codewords interleaved: 2x12 errors can be corrected;
// CRC is good for list decoding, high rate is not;
// burst errors could affect neighboring bytes, however // burst errors could affect neighboring bytes, however
// if AWGN and 24 bit-errors per frame, probability for 2 bit-errors in 1 byte is low; // if AWGN and 24 bit-errors per frame, probability for 2 bit-errors in 1 byte is low;
// erasures: 11 + 2/2 = 12 (11 errors and 2 erasures per codeword can be corrected) // erasures: 11 + 2/2 = 12 (11 errors and 2 erasures per codeword can be corrected)
@ -1195,14 +1196,14 @@ static int rs41_ecc(gpx_t *gpx, int frmlen) {
if (errors1 < 0) if (errors1 < 0)
{ {
for (i = 1; i < Era_max; i++) { for (i = 1; i < Era_max; i++) {
pos_frm = sort_idx1[i]; pos_frm = gpx->ecdat.sort_idx1[i];
if (inFixed(gpx, pos_frm)) continue; if (inFixed(gpx, pos_frm)) continue;
if (pos_frm < cfg_rs41.msgpos) pos_cw = pos_frm - cfg_rs41.parpos; if (pos_frm < cfg_rs41.msgpos) pos_cw = pos_frm - cfg_rs41.parpos;
else pos_cw = rs_R + (pos_frm - cfg_rs41.msgpos)/2; else pos_cw = rs_R + (pos_frm - cfg_rs41.msgpos)/2;
if (pos_cw < 0 || pos_cw > 254) continue; if (pos_cw < 0 || pos_cw > 254) continue;
era_pos[0] = pos_cw; era_pos[0] = pos_cw;
for (j = 0; j < i; j++) { for (j = 0; j < i; j++) {
pos_frm = sort_idx1[j]; pos_frm = gpx->ecdat.sort_idx1[j];
if (inFixed(gpx, pos_frm)) continue; if (inFixed(gpx, pos_frm)) continue;
if (pos_frm < cfg_rs41.msgpos) pos_cw = pos_frm - cfg_rs41.parpos; if (pos_frm < cfg_rs41.msgpos) pos_cw = pos_frm - cfg_rs41.parpos;
else pos_cw = rs_R + (pos_frm - cfg_rs41.msgpos)/2; else pos_cw = rs_R + (pos_frm - cfg_rs41.msgpos)/2;
@ -1217,14 +1218,14 @@ static int rs41_ecc(gpx_t *gpx, int frmlen) {
if (errors2 < 0) if (errors2 < 0)
{ {
for (i = 1; i < Era_max; i++) { for (i = 1; i < Era_max; i++) {
pos_frm = sort_idx2[i]; pos_frm = gpx->ecdat.sort_idx2[i];
if (inFixed(gpx, pos_frm)) continue; if (inFixed(gpx, pos_frm)) continue;
if (pos_frm < cfg_rs41.msgpos) pos_cw = pos_frm - cfg_rs41.parpos - rs_R; if (pos_frm < cfg_rs41.msgpos) pos_cw = pos_frm - cfg_rs41.parpos - rs_R;
else pos_cw = rs_R + (pos_frm - cfg_rs41.msgpos)/2; else pos_cw = rs_R + (pos_frm - cfg_rs41.msgpos)/2;
if (pos_cw < 0 || pos_cw > 254) continue; if (pos_cw < 0 || pos_cw > 254) continue;
era_pos[0] = pos_cw; era_pos[0] = pos_cw;
for (j = 0; j < i; j++) { for (j = 0; j < i; j++) {
pos_frm = sort_idx2[j]; pos_frm = gpx->ecdat.sort_idx2[j];
if (inFixed(gpx, pos_frm)) continue; if (inFixed(gpx, pos_frm)) continue;
if (pos_frm < cfg_rs41.msgpos) pos_cw = pos_frm - cfg_rs41.parpos - rs_R; if (pos_frm < cfg_rs41.msgpos) pos_cw = pos_frm - cfg_rs41.parpos - rs_R;
else pos_cw = rs_R + (pos_frm - cfg_rs41.msgpos)/2; else pos_cw = rs_R + (pos_frm - cfg_rs41.msgpos)/2;
@ -1630,8 +1631,7 @@ static void print_frame(gpx_t *gpx, int len) {
int j1 = 0; int j1 = 0;
int j2 = 0; int j2 = 0;
int sort_score_idx[FRAME_LEN]; int sort_score_idx[FRAME_LEN];
float byte_min_score[FRAME_LEN]; float max_minscore = 0.0;
float max_score = 0.0;
gpx->crc = 0; gpx->crc = 0;
@ -1647,41 +1647,34 @@ static void print_frame(gpx_t *gpx, int len) {
else len = FRAME_LEN; // ft < 0: FRAME_LEN (aux) else len = FRAME_LEN; // ft < 0: FRAME_LEN (aux)
for (i = FRAMESTART; i < BITS*len; i++) { for (i = FRAMESTART; i < len; i++) {
if (fabs(ecdat.frm_softbits[i]) > max_score) max_score = fabs(ecdat.frm_softbits[i]); if (fabs(gpx->ecdat.frm_bytescore[i]) > max_minscore) max_minscore = fabs(gpx->ecdat.frm_bytescore[i]);
} }
max_score = floor(max_score+1.5); max_minscore = floor(max_minscore+1.5);
for (i = 0; i < FRAME_LEN; i++) byte_min_score[i] = max_score;
if (gpx->option.ecc > 2) { if (gpx->option.ecc > 2) {
for (i = FRAMESTART; i < len; i++) { for (i = 0; i < FRAMESTART; i++) gpx->ecdat.frm_bytescore[i] = max_minscore*2.0; //*sign
float min_score_byte = ecdat.frm_softbits[BITS*i]; for (i = len; i < FRAME_LEN; i++) gpx->ecdat.frm_bytescore[i] = max_minscore;
for (j = 1; j < 8; j++) {
float serr = ecdat.frm_softbits[BITS*i+j];
if (fabs(serr) < fabs(min_score_byte)) min_score_byte = ecdat.frm_softbits[BITS*i+j];
}
byte_min_score[i] = min_score_byte;
}
} }
for (i = 0; i < FRAME_LEN; i++) sort_score_idx[i] = i; for (i = 0; i < FRAME_LEN; i++) sort_score_idx[i] = i;
if (gpx->option.ecc > 2) { if (gpx->option.ecc > 2) {
for (i = 0; i < FRAME_LEN; i++) { for (i = 0; i < FRAME_LEN; i++) {
for (j = 0; j < FRAME_LEN-1; j++) { for (j = 0; j < FRAME_LEN-1; j++) {
if (fabs(byte_min_score[sort_score_idx[j+1]]) < fabs(byte_min_score[sort_score_idx[j]])) { if (fabs(gpx->ecdat.frm_bytescore[sort_score_idx[j+1]]) < fabs(gpx->ecdat.frm_bytescore[sort_score_idx[j]])) {
int tmp = sort_score_idx[j+1]; int tmp = sort_score_idx[j+1];
sort_score_idx[j+1] = sort_score_idx[j]; sort_score_idx[j+1] = sort_score_idx[j];
sort_score_idx[j] = tmp; sort_score_idx[j] = tmp;
} }
} }
} }
for (i = 0; i < FRAME_LEN; i++) sort_idx1[i] = i; for (i = 0; i < FRAME_LEN; i++) gpx->ecdat.sort_idx1[i] = i;
for (i = 0; i < FRAME_LEN; i++) sort_idx2[i] = i; for (i = 0; i < FRAME_LEN; i++) gpx->ecdat.sort_idx2[i] = i;
j1 = 0; j1 = 0;
j2 = 0; j2 = 0;
for (i = 0; i < FRAME_LEN; i++) { for (i = 0; i < FRAME_LEN; i++) {
if (sort_score_idx[i] >= cfg_rs41.parpos && sort_score_idx[i] < cfg_rs41.parpos+ rs_R) sort_idx1[j1++] = sort_score_idx[i]; if (sort_score_idx[i] >= cfg_rs41.parpos && sort_score_idx[i] < cfg_rs41.parpos+ rs_R) gpx->ecdat.sort_idx1[j1++] = sort_score_idx[i];
else if (sort_score_idx[i] >= cfg_rs41.parpos+rs_R && sort_score_idx[i] < cfg_rs41.parpos+2*rs_R) sort_idx2[j2++] = sort_score_idx[i]; else if (sort_score_idx[i] >= cfg_rs41.parpos+rs_R && sort_score_idx[i] < cfg_rs41.parpos+2*rs_R) gpx->ecdat.sort_idx2[j2++] = sort_score_idx[i];
else if (sort_score_idx[i] >= cfg_rs41.msgpos && sort_score_idx[i] % 2 == 0) sort_idx1[j1++] = sort_score_idx[i]; else if (sort_score_idx[i] >= cfg_rs41.msgpos && sort_score_idx[i] % 2 == 0) gpx->ecdat.sort_idx1[j1++] = sort_score_idx[i];
else if (sort_score_idx[i] >= cfg_rs41.msgpos && sort_score_idx[i] % 2 == 1) sort_idx2[j2++] = sort_score_idx[i]; else if (sort_score_idx[i] >= cfg_rs41.msgpos && sort_score_idx[i] % 2 == 1) gpx->ecdat.sort_idx2[j2++] = sort_score_idx[i];
} }
} }
@ -1761,6 +1754,7 @@ int main(int argc, char *argv[]) {
gpx_t gpx = {0}; gpx_t gpx = {0};
hdb_t hdb = {0}; hdb_t hdb = {0};
float softbits[BITS];
#ifdef CYGWIN #ifdef CYGWIN
@ -2016,12 +2010,20 @@ int main(int argc, char *argv[]) {
{ {
if (option_bin) { if (option_bin) {
bitQ = fgetc(fp); bitQ = fgetc(fp);
if (bitQ != EOF) bit = bitQ & 0x1; if (bitQ != EOF) {
bit = bitQ & 0x1;
hsbit.hb = bit;
hsbit.sb = 2*bit-1;
}
} }
else if (option_softin) { else if (option_softin) {
float s = 0.0; float s = 0.0;
bitQ = f32soft_read(fp, &s); bitQ = f32soft_read(fp, &s);
if (bitQ != EOF) bit = (s>=0.0); // no soft decoding if (bitQ != EOF) {
bit = (s>=0.0);
hsbit.hb = bit;
hsbit.sb = s;
}
} }
else { else {
float bl = -1; float bl = -1;
@ -2034,16 +2036,23 @@ int main(int argc, char *argv[]) {
if (bitpos < FRAME_LEN*BITS && hsbit.sb*hsbit1.sb < 0) { if (bitpos < FRAME_LEN*BITS && hsbit.sb*hsbit1.sb < 0) {
difbyte |= 1<<b8pos; difbyte |= 1<<b8pos;
} }
ecdat.frm_softbits[HEADLEN + bitpos] = hsbit.sb;
} }
if ( bitQ == EOF ) break; // liest 2x EOF if ( bitQ == EOF ) break; // liest 2x EOF
softbits[b8pos] = hsbit.sb;
if (gpx.option.inv) bit ^= 1; if (gpx.option.inv) bit ^= 1;
bitpos += 1; bitpos += 1;
bitbuf[b8pos] = bit; bitbuf[b8pos] = bit;
b8pos++; b8pos++;
if (b8pos == BITS) { if (b8pos == BITS) {
int j;
float min_score_byte = softbits[0];
for (j = 1; j < BITS; j++) {
if (fabs(softbits[j]) < fabs(min_score_byte)) min_score_byte = softbits[j];
}
gpx.ecdat.frm_bytescore[byte_count] = min_score_byte;
b8pos = 0; b8pos = 0;
byte = bits2byte(bitbuf); byte = bits2byte(bitbuf);
gpx.frame[byte_count] = byte ^ mask[byte_count % MASK_LEN]; gpx.frame[byte_count] = byte ^ mask[byte_count % MASK_LEN];
@ -2052,7 +2061,7 @@ int main(int argc, char *argv[]) {
byte_count++; byte_count++;
} }
} }
ecdat.ts = dsp.mv_pos/(float)dsp.sr; gpx.ecdat.ts = dsp.mv_pos/(float)dsp.sr;
print_frame(&gpx, byte_count); print_frame(&gpx, byte_count);
byte_count = FRAMESTART; byte_count = FRAMESTART;