Try all phases if --oversample --phase-enhance is on.
If we demodulate a message in 2.4MHz mode and it has a bad, uncorrectable CRC, and --phase-enhance is on, then retry with the other possible phases until we get a good CRC or run out of phases to try. This is very expensive in AGC mode (lots of candidates that are not real messages) but relatively cheap otherwise. It yields another 10% messages. Also factor out some common stats code to avoid lots more copy/paste.
This commit is contained in:
Oliver Jowett
parent
93e1b9e10d
commit
c11eca44bb
3 changed files with 133 additions and 143 deletions
137
mode_s.c
137
mode_s.c
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@ -1818,49 +1818,25 @@ void detectModeS(uint16_t *m, uint32_t mlen) {
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// Update statistics
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if (Modes.stats) {
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if (mm.crcok || use_correction || mm.correctedbits) {
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struct demod_stats *dstats = (use_correction ? &Modes.stat_demod_phasecorrected : &Modes.stat_demod);
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if (use_correction) {
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switch (errors) {
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case 0: {Modes.stat_ph_demodulated0++; break;}
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case 1: {Modes.stat_ph_demodulated1++; break;}
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case 2: {Modes.stat_ph_demodulated2++; break;}
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default:{Modes.stat_ph_demodulated3++; break;}
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}
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} else {
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switch (errors) {
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case 0: {Modes.stat_demodulated0++; break;}
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case 1: {Modes.stat_demodulated1++; break;}
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case 2: {Modes.stat_demodulated2++; break;}
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default:{Modes.stat_demodulated3++; break;}
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}
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}
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if (mm.correctedbits == 0) {
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if (use_correction) {
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if (mm.crcok) {Modes.stat_ph_goodcrc++;}
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else {Modes.stat_ph_badcrc++;}
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} else {
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if (mm.crcok) {Modes.stat_goodcrc++;}
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else {Modes.stat_badcrc++;}
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}
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} else if (use_correction) {
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Modes.stat_ph_badcrc++;
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Modes.stat_ph_fixed++;
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if ( (mm.correctedbits)
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&& (mm.correctedbits <= MODES_MAX_BITERRORS) ) {
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Modes.stat_ph_bit_fix[mm.correctedbits-1] += 1;
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}
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} else {
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Modes.stat_badcrc++;
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Modes.stat_fixed++;
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if ( (mm.correctedbits)
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&& (mm.correctedbits <= MODES_MAX_BITERRORS) ) {
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Modes.stat_bit_fix[mm.correctedbits-1] += 1;
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}
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}
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switch (errors) {
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case 0: dstats->demodulated0++; break;
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case 1: dstats->demodulated1++; break;
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case 2: dstats->demodulated2++; break;
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default: dstats->demodulated3++; break;
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}
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if (mm.crcok) {
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dstats->goodcrc++;
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dstats->goodcrc_byphase[0]++;
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} else if (mm.correctedbits > 0) {
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dstats->badcrc++;
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dstats->fixed++;
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if (mm.correctedbits <= MODES_MAX_BITERRORS)
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dstats->bit_fix[mm.correctedbits-1] += 1;
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} else {
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dstats->badcrc++;
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}
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}
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@ -1878,7 +1854,7 @@ void detectModeS(uint16_t *m, uint32_t mlen) {
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}
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// Skip this message if we are sure it's fine
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if (mm.crcok) {
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if (mm.crcok || mm.correctedbits) {
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j += (MODES_PREAMBLE_US+msglen)*2 - 1;
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}
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@ -1972,19 +1948,19 @@ static inline int slice_phase4(uint16_t *m) {
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}
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static inline int correlate_phase0(uint16_t *m) {
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return slice_phase0(m) * 3;
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return slice_phase0(m) * 26;
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}
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static inline int correlate_phase1(uint16_t *m) {
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return slice_phase1(m) * 4;
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return slice_phase1(m) * 38;
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}
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static inline int correlate_phase2(uint16_t *m) {
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return slice_phase2(m) * 4;
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return slice_phase2(m) * 38;
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}
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static inline int correlate_phase3(uint16_t *m) {
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return slice_phase3(m) * 3;
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return slice_phase3(m) * 26;
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}
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static inline int correlate_phase4(uint16_t *m) {
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return slice_phase4(m) * 2;
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return slice_phase4(m) * 19;
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}
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//
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@ -2092,6 +2068,7 @@ void detectModeS_oversample(uint16_t *m, uint32_t mlen) {
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uint8_t theByte, theErrs;
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uint32_t sigLevel, noiseLevel;
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uint16_t snr;
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int try_phase;
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// Look for a message starting at around sample 0 with phase offset 3..7
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@ -2183,6 +2160,9 @@ void detectModeS_oversample(uint16_t *m, uint32_t mlen) {
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Modes.stat_valid_preamble++;
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Modes.stat_preamble_phase[initial_phase%MODES_MAX_PHASE_STATS]++;
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try_phase = initial_phase;
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retry:
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// Rather than clear the whole mm structure, just clear the parts which are required. The clear
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// is required for every possible preamble, and we don't want to be memset-ing the whole
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// modesMessage structure if we don't have to..
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@ -2192,10 +2172,10 @@ void detectModeS_oversample(uint16_t *m, uint32_t mlen) {
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// Decode all the next 112 bits, regardless of the actual message
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// size. We'll check the actual message type later
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pMsg = &msg[0];
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pPtr = &m[j+19] + (initial_phase/5);
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phase = initial_phase % 5;
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pPtr = &m[j+19] + (try_phase/5);
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phase = try_phase % 5;
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theByte = 0;
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theErrs = 0; errorsTy = 0;
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errors = 0; errors56 = 0;
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@ -2369,46 +2349,59 @@ void detectModeS_oversample(uint16_t *m, uint32_t mlen) {
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// && ((2 * snr) > (int) (MODES_MSG_SQUELCH_DB * 10))
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&& (errors <= MODES_MSG_ENCODER_ERRS) ) {
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// Set initial mm structure details
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mm.timestampMsg = Modes.timestampBlk + (j*5) + initial_phase;
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mm.timestampMsg = Modes.timestampBlk + (j*5) + try_phase;
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mm.signalLevel = (snr > 255 ? 255 : (uint8_t)snr);
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mm.phase_corrected = 0;
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//dumpRawMessage("decoded with oversampling", msg, m, j);
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mm.phase_corrected = (initial_phase != try_phase);
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// Decode the received message
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decodeModesMessage(&mm, msg);
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// Update statistics
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if (Modes.stats) {
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struct demod_stats *dstats = (mm.phase_corrected ? &Modes.stat_demod_phasecorrected : &Modes.stat_demod);
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switch (errors) {
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case 0: {Modes.stat_demodulated0++; break;}
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case 1: {Modes.stat_demodulated1++; break;}
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case 2: {Modes.stat_demodulated2++; break;}
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default:{Modes.stat_demodulated3++; break;}
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case 0: dstats->demodulated0++; break;
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case 1: dstats->demodulated1++; break;
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case 2: dstats->demodulated2++; break;
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default: dstats->demodulated3++; break;
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}
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if (mm.correctedbits == 0) {
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if (mm.crcok) {
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Modes.stat_goodcrc++;
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Modes.stat_goodcrc_phase[initial_phase%MODES_MAX_PHASE_STATS]++;
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} else {Modes.stat_badcrc++;}
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if (mm.crcok) {
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dstats->goodcrc++;
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dstats->goodcrc_byphase[try_phase%MODES_MAX_PHASE_STATS]++;
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} else if (mm.correctedbits > 0) {
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dstats->badcrc++;
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dstats->fixed++;
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if (mm.correctedbits <= MODES_MAX_BITERRORS)
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dstats->bit_fix[mm.correctedbits-1] += 1;
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} else {
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Modes.stat_badcrc++;
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Modes.stat_fixed++;
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if ( (mm.correctedbits)
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&& (mm.correctedbits <= MODES_MAX_BITERRORS) ) {
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Modes.stat_bit_fix[mm.correctedbits-1] += 1;
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}
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dstats->badcrc++;
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}
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}
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// Skip this message if we are sure it's fine
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if (mm.crcok) {
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if (mm.crcok || mm.correctedbits) {
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j += (16+msglen)*6/5 - 1;
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}
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// Pass data to the next layer
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useModesMessage(&mm);
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// Only try with different phases if we mostly demodulated OK,
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// but the CRC failed. This seems to catch most of the cases
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// where trying different phases actually helps, and is much
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// cheaper than trying it on every single candidate that passes
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// peak detection
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if (Modes.phase_enhance && !mm.crcok && !mm.correctedbits) {
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if (try_phase == initial_phase)
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++Modes.stat_out_of_phase;
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try_phase++;
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if (try_phase == 9)
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try_phase = 4;
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if (try_phase != initial_phase)
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goto retry;
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}
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}
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}
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