Ditch SNR calcs too.
This commit is contained in:
Oliver Jowett
parent
00e232cc4f
commit
20456a83fd
86
demod_2400.c
86
demod_2400.c
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@ -155,7 +155,7 @@ void demodulate2400(uint16_t *m, uint32_t mlen) {
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uint32_t j;
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uint32_t j;
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unsigned char *bestmsg;
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unsigned char *bestmsg;
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int bestscore, bestphase, bestsnr;
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int bestscore, bestphase;
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memset(&mm, 0, sizeof(mm));
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memset(&mm, 0, sizeof(mm));
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msg = msg1;
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msg = msg1;
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@ -263,11 +263,10 @@ void demodulate2400(uint16_t *m, uint32_t mlen) {
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}
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}
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Modes.stats_current.valid_preamble++;
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Modes.stats_current.valid_preamble++;
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bestmsg = NULL; bestscore = -1; bestphase = -1; bestsnr = -1;
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bestmsg = NULL; bestscore = -1; bestphase = -1;
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for (try_phase = first_phase; try_phase <= last_phase; ++try_phase) {
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for (try_phase = first_phase; try_phase <= last_phase; ++try_phase) {
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int sigLevel = base_signal, noiseLevel = base_noise;
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uint16_t *pPtr;
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uint16_t *pPtr;
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int phase, i, snr, score, bytelen;
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int phase, i, score, bytelen;
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// Decode all the next 112 bits, regardless of the actual message
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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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// size. We'll check the actual message type later
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@ -291,21 +290,6 @@ void demodulate2400(uint16_t *m, uint32_t mlen) {
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(slice_phase2(pPtr+14) > 0 ? 0x02 : 0) |
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(slice_phase2(pPtr+14) > 0 ? 0x02 : 0) |
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(slice_phase4(pPtr+16) > 0 ? 0x01 : 0);
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(slice_phase4(pPtr+16) > 0 ? 0x01 : 0);
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if (theByte & 0x20) {
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sigLevel += pPtr[5];
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noiseLevel += pPtr[6];
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} else {
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noiseLevel += pPtr[5];
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sigLevel += pPtr[6];
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}
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if (theByte & 0x01) {
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sigLevel += pPtr[17];
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noiseLevel += pPtr[18];
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} else {
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noiseLevel += pPtr[17];
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sigLevel += pPtr[18];
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}
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phase = 1;
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phase = 1;
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pPtr += 19;
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pPtr += 19;
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@ -322,14 +306,6 @@ void demodulate2400(uint16_t *m, uint32_t mlen) {
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(slice_phase3(pPtr+14) > 0 ? 0x02 : 0) |
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(slice_phase3(pPtr+14) > 0 ? 0x02 : 0) |
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(slice_phase0(pPtr+17) > 0 ? 0x01 : 0);
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(slice_phase0(pPtr+17) > 0 ? 0x01 : 0);
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if (theByte & 0x08) {
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sigLevel += pPtr[10];
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noiseLevel += pPtr[11];
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} else {
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noiseLevel += pPtr[10];
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sigLevel += pPtr[11];
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}
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phase = 2;
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phase = 2;
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pPtr += 19;
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pPtr += 19;
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break;
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break;
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@ -345,22 +321,6 @@ void demodulate2400(uint16_t *m, uint32_t mlen) {
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(slice_phase4(pPtr+14) > 0 ? 0x02 : 0) |
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(slice_phase4(pPtr+14) > 0 ? 0x02 : 0) |
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(slice_phase1(pPtr+17) > 0 ? 0x01 : 0);
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(slice_phase1(pPtr+17) > 0 ? 0x01 : 0);
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if (theByte & 0x40) {
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sigLevel += pPtr[3];
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noiseLevel += pPtr[4];
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} else {
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noiseLevel += pPtr[3];
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sigLevel += pPtr[4];
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}
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if (theByte & 0x02) {
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sigLevel += pPtr[15];
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noiseLevel += pPtr[16];
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} else {
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noiseLevel += pPtr[15];
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sigLevel += pPtr[16];
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}
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phase = 3;
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phase = 3;
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pPtr += 19;
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pPtr += 19;
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break;
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break;
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@ -376,14 +336,6 @@ void demodulate2400(uint16_t *m, uint32_t mlen) {
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(slice_phase0(pPtr+15) > 0 ? 0x02 : 0) |
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(slice_phase0(pPtr+15) > 0 ? 0x02 : 0) |
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(slice_phase2(pPtr+17) > 0 ? 0x01 : 0);
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(slice_phase2(pPtr+17) > 0 ? 0x01 : 0);
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if (theByte & 0x10) {
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sigLevel += pPtr[8];
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noiseLevel += pPtr[9];
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} else {
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noiseLevel += pPtr[8];
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sigLevel += pPtr[9];
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}
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phase = 4;
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phase = 4;
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pPtr += 19;
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pPtr += 19;
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break;
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break;
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@ -399,23 +351,6 @@ void demodulate2400(uint16_t *m, uint32_t mlen) {
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(slice_phase1(pPtr+15) > 0 ? 0x02 : 0) |
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(slice_phase1(pPtr+15) > 0 ? 0x02 : 0) |
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(slice_phase3(pPtr+17) > 0 ? 0x01 : 0);
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(slice_phase3(pPtr+17) > 0 ? 0x01 : 0);
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if (theByte & 0x80) {
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sigLevel += pPtr[1];
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noiseLevel += pPtr[2];
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} else {
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noiseLevel += pPtr[1];
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sigLevel += pPtr[2];
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}
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if (theByte & 0x04) {
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sigLevel += pPtr[13];
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noiseLevel += pPtr[14];
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} else {
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noiseLevel += pPtr[13];
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sigLevel += pPtr[14];
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}
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phase = 0;
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phase = 0;
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pPtr += 20;
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pPtr += 20;
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break;
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break;
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@ -442,25 +377,11 @@ void demodulate2400(uint16_t *m, uint32_t mlen) {
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if (score < 0)
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if (score < 0)
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continue; // can't decode
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continue; // can't decode
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// apply the SNR to the score, so less noisy decodes are better,
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// all things being equal
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// snr = 5 * 20log10(sigLevel / noiseLevel) (in units of 0.2dB)
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// = 100log10(sigLevel) - 100log10(noiseLevel)
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while (sigLevel > 65535 || noiseLevel > 65535) {
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sigLevel >>= 1;
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noiseLevel >>= 1;
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}
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snr = Modes.log10lut[sigLevel] - Modes.log10lut[noiseLevel];
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score += snr;
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if (score > bestscore) {
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if (score > bestscore) {
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// new high score!
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// new high score!
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bestmsg = msg;
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bestmsg = msg;
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bestscore = score;
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bestscore = score;
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bestphase = try_phase;
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bestphase = try_phase;
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bestsnr = snr;
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// swap to using the other buffer so we don't clobber our demodulated data
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// swap to using the other buffer so we don't clobber our demodulated data
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// (if we find a better result then we'll swap back, but that's OK because
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// (if we find a better result then we'll swap back, but that's OK because
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@ -479,7 +400,6 @@ void demodulate2400(uint16_t *m, uint32_t mlen) {
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// Set initial mm structure details
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// Set initial mm structure details
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mm.timestampMsg = Modes.timestampBlk + (j*5) + bestphase;
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mm.timestampMsg = Modes.timestampBlk + (j*5) + bestphase;
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mm.signalLevel = (bestsnr > 255 ? 255 : (uint8_t)bestsnr);
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mm.score = bestscore;
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mm.score = bestscore;
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mm.bFlags = mm.correctedbits = 0;
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mm.bFlags = mm.correctedbits = 0;
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