kopia lustrzana https://github.com/OpenRTX/OpenRTX
Improve quantization strategy
Now quantization is performed by averaging syncword samples and dividing the resulting threshold by a constant. TG-81pull/68/head
Niccolò Izzo
Silvano Seva
rodzic
2e7ed7a8f0
commit
c4483edff0
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@ -125,7 +125,7 @@ private:
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static constexpr float CONV_STATS_ALPHA = 0.001f;
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static constexpr float CONV_THRESHOLD_FACTOR = 3.40;
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static constexpr int16_t QNT_SMA_WINDOW = 40;
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static constexpr int16_t QNT_SMA_WINDOW = 8;
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/**
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* M17 syncwords;
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@ -142,7 +142,7 @@ private:
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int16_t *baseband_buffer; ///< Buffer for baseband audio handling.
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dataBlock_t baseband; ///< Half buffer, free to be processed.
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uint16_t *rawFrame; ///< Analog values to be quantized.
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uint16_t frameIndex; ///< Index for filling the raw frame.
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uint16_t frame_index; ///< Index for filling the raw frame.
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frame_t *activeFrame; ///< Half frame, in demodulation.
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frame_t *idleFrame; ///< Half frame, free to be processed.
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bool isLSF; ///< Indicates that we demodualated an LSF.
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@ -60,7 +60,7 @@ void M17Demodulator::init()
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activeFrame = new frame_t;
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rawFrame = new uint16_t[M17_FRAME_SYMBOLS];
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idleFrame = new frame_t;
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frameIndex = 0;
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frame_index = 0;
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phase = 0;
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locked = false;
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newFrame = false;
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@ -90,6 +90,7 @@ void M17Demodulator::startBasebandSampling()
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M17_RX_SAMPLE_RATE);
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// Clean start of the demodulation statistics
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resetCorrelationStats();
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resetQuantizationStats();
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// DC removal filter reset
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dsp_resetFilterState(&dsp_state);
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}
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@ -135,25 +136,39 @@ void M17Demodulator::updateQuantizationStats(int32_t offset)
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sample = baseband.data[offset];
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if (sample > 0)
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{
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// If the FIFO is not full just push a new sample
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if (qnt_pos_fifo.size() >= QNT_SMA_WINDOW)
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qnt_pos_fifo.push_front(sample);
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// FIFO not full, compute traditional average
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if (qnt_pos_fifo.size() <= QNT_SMA_WINDOW)
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{
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int32_t acc = 0;
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for(auto e : qnt_pos_fifo)
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acc += e;
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qnt_pos_avg = acc / static_cast<float>(qnt_pos_fifo.size());
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}
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else
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{
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qnt_pos_avg += 1 / static_cast<float>(QNT_SMA_WINDOW) *
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(sample - qnt_pos_fifo.back());
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qnt_pos_fifo.pop_back();
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}
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qnt_pos_fifo.push_front(sample);
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}
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else
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{
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// If the FIFO is not full just push a new sample
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if (qnt_neg_fifo.size() >= QNT_SMA_WINDOW)
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qnt_neg_fifo.push_front(sample);
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// FIFO not full, compute traditional average
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if (qnt_neg_fifo.size() <= QNT_SMA_WINDOW)
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{
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int32_t acc = 0;
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for(auto e : qnt_neg_fifo)
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acc += e;
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qnt_neg_avg = acc / static_cast<float>(qnt_neg_fifo.size());
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}
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else
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{
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qnt_neg_avg += 1 / static_cast<float>(QNT_SMA_WINDOW) *
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(sample - qnt_neg_fifo.back());
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qnt_neg_fifo.pop_back();
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}
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qnt_neg_fifo.push_front(sample);
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}
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}
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@ -194,7 +209,6 @@ sync_t M17Demodulator::nextFrameSync(int32_t offset)
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// If we are not locked search for a syncword
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int32_t conv = convolution(i, stream_syncword, M17_SYNCWORD_SYMBOLS);
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updateCorrelationStats(conv);
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updateQuantizationStats(i);
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#ifdef PLATFORM_LINUX
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int16_t sample = 0;
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@ -239,9 +253,9 @@ int8_t M17Demodulator::quantize(int32_t offset)
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sample = basebandBridge[M17_BRIDGE_SIZE + offset];
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else // Otherwise use regular data buffer
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sample = baseband.data[offset];
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if (sample > static_cast< int16_t >(qnt_pos_avg * 0.067))
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if (sample > static_cast< int16_t >(qnt_pos_avg / 1.7))
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return +3;
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else if (sample < static_cast< int16_t >(qnt_neg_avg * 0.067))
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else if (sample < static_cast< int16_t >(qnt_neg_avg / 1.7))
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return -3;
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else if (sample > 0)
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return +1;
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@ -312,7 +326,7 @@ bool M17Demodulator::update()
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isLSF = syncword.lsf;
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offset = syncword.index + 4;
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phase = 0;
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frameIndex = 0;
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frame_index = 0;
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}
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}
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// While we are locked, demodulate available samples
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@ -322,8 +336,9 @@ bool M17Demodulator::update()
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int32_t symbol_index = offset
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+ phase
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+ (M17_SAMPLES_PER_SYMBOL * decoded_syms);
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updateQuantizationStats(symbol_index);
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// Update quantization stats only on syncwords
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if (frame_index < M17_SYNCWORD_SYMBOLS)
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updateQuantizationStats(symbol_index);
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int8_t symbol = quantize(symbol_index);
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#ifdef PLATFORM_LINUX
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@ -333,63 +348,64 @@ bool M17Demodulator::update()
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fprintf(csv_log, "%" PRId16 ",%d,%f,%d,%" PRId16 ",%f,%f,%d,%d\n",
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0,0,0.0,symbol_index - 4 + i,
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baseband.data[symbol_index - 4 + i],
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qnt_pos_avg,
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qnt_neg_avg,
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qnt_pos_avg / 1.7,
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qnt_neg_avg / 1.7,
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0,
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frameIndex);
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frame_index);
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}
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fprintf(csv_log, "%" PRId16 ",%d,%f,%d,%" PRId16 ",%f,%f,%d,%d\n",
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0,0,0.0,symbol_index,
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baseband.data[symbol_index],
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qnt_pos_avg,
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qnt_neg_avg,
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qnt_pos_avg / 1.7,
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qnt_neg_avg / 1.7,
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symbol * 666,
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frameIndex);
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frame_index);
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for (int i = 0; i < 5; i++)
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{
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if ((symbol_index + i + 1) < static_cast<int32_t> (baseband.len))
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fprintf(csv_log, "%" PRId16 ",%d,%f,%d,%" PRId16 ",%f,%f,%d,%d\n",
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0,0,0.0,symbol_index + i + 1,
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baseband.data[symbol_index + i + 1],
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qnt_pos_avg,
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qnt_neg_avg,
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qnt_pos_avg / 1.7,
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qnt_neg_avg / 1.7,
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0,
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frameIndex);
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frame_index);
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}
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fflush(csv_log);
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#endif
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setSymbol<M17_FRAME_BYTES>(*activeFrame, frameIndex, symbol);
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setSymbol<M17_FRAME_BYTES>(*activeFrame, frame_index, symbol);
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decoded_syms++;
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frameIndex++;
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frame_index++;
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// If the frame buffer is full switch active and idle frame
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if (frameIndex == M17_FRAME_SYMBOLS)
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if (frame_index == M17_FRAME_SYMBOLS)
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{
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std::swap(activeFrame, idleFrame);
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frameIndex = 0;
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frame_index = 0;
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newFrame = true;
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}
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// If syncword is not valid, lock is lost, accept 2 bit errors
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uint8_t hammingSync = hammingDistance((*activeFrame)[0],
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stream_syncword_bytes[0])
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+ hammingDistance((*activeFrame)[1],
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stream_syncword_bytes[1]);
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uint8_t hammingLsf = hammingDistance((*activeFrame)[0],
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lsf_syncword_bytes[0])
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+ hammingDistance((*activeFrame)[1],
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lsf_syncword_bytes[1]);
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if (frameIndex == M17_SYNCWORD_SYMBOLS)
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if (frame_index == M17_SYNCWORD_SYMBOLS)
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{
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// If syncword is not valid, lock is lost, accept 2 bit errors
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uint8_t hammingSync = hammingDistance((*activeFrame)[0],
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stream_syncword_bytes[0])
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+ hammingDistance((*activeFrame)[1],
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stream_syncword_bytes[1]);
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uint8_t hammingLsf = hammingDistance((*activeFrame)[0],
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lsf_syncword_bytes[0])
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+ hammingDistance((*activeFrame)[1],
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lsf_syncword_bytes[1]);
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// Too many errors in the syncword, lock is lost
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if ((hammingSync > 1) && (hammingLsf > 1))
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{
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locked = false;
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std::swap(activeFrame, idleFrame);
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frameIndex = 0;
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frame_index = 0;
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newFrame = true;
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#ifdef PLATFORM_MOD17
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@ -15,6 +15,6 @@ plt.plot(df.index, df.Offset)
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plt.plot(df.index, df.Sample)
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plt.plot(df.index, df.Max)
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plt.plot(df.index, df.Min)
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#plt.plot(df.index, df.Symbol)
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plt.plot(df.index, df.Symbol)
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plt.plot(df.index, df.I)
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plt.show()
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