Removed a printf left behind after debugging from M17 demodulator class and slightly cleaned up the code
This commit is contained in:
Silvano Seva
parent
163a2ef06a
commit
54a89abcd0
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@ -42,7 +42,8 @@ typedef struct
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{
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int32_t index;
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bool lsf;
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} sync_t;
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}
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sync_t;
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class M17Demodulator
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{
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@ -153,20 +154,15 @@ private:
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/*
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* Convolution statistics computation
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*/
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float conv_ema = 0.0f;
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float conv_ema = 0.0f; /// Exponential moving average from all the correlation values.
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float conv_emvar = 0.0f;
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/*
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* Quantization statistics computation
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*/
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float qnt_ema = 0.0f;
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float qnt_max = 0.0f;
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float qnt_min = 0.0f;
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/**
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* Deque containing the sliced samples
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*/
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// std::deque<int16_t> samples_fifo;
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float qnt_ema = 0.0f; ///< Exponential moving average from of the sliced samples.
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float qnt_max = 0.0f; ///< Max hold of the sliced samples
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float qnt_min = 0.0f; ///< Min hold of the sliced samples.
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/**
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* Resets the exponential mean and variance/stddev computation.
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@ -181,13 +177,6 @@ private:
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*/
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void updateCorrelationStats(int32_t value);
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/**
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* Returns the exponential moving average from all the correlation values.
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*
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* @returns float numerical value of the exponential moving average
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*/
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float getCorrelationEma();
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/**
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* Returns the standard deviation from all the correlation values.
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*
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@ -208,27 +197,6 @@ private:
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*/
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void updateQuantizationStats(int32_t offset);
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/**
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* Returns the exponential moving average from of the sliced samples.
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*
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* @returns float numerical value of the exponential moving average
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*/
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float getQuantizationEma();
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/**
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* Returns the max hold of the sliced samples.
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*
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* @returns float numerical value of the max hold
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*/
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float getQuantizationMax();
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/**
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* Returns the min hold of the sliced samples.
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*
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* @returns float numerical value of the min hold
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*/
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float getQuantizationMin();
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/**
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* Computes the convolution between a stride of samples starting from
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* a given offset and a target waveform.
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@ -35,8 +35,7 @@
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#include <emulator.h>
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#endif
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namespace M17
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{
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using namespace M17;
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M17Demodulator::M17Demodulator()
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{
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@ -103,7 +102,7 @@ void M17Demodulator::stopBasebandSampling()
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void M17Demodulator::resetCorrelationStats()
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{
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conv_ema = 0.0f;
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conv_ema = 0.0f;
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conv_emvar = 800000000.0f;
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}
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@ -119,11 +118,6 @@ void M17Demodulator::updateCorrelationStats(int32_t value)
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conv_emvar = (1.0f - conv_stats_alpha) * (conv_emvar + delta * incr);
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}
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float M17Demodulator::getCorrelationEma()
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{
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return conv_ema;
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}
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float M17Demodulator::getCorrelationStddev()
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{
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return sqrt(conv_emvar);
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@ -159,21 +153,6 @@ void M17Demodulator::updateQuantizationStats(int32_t offset)
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qnt_min *= qnt_stats_alpha;
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}
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float M17Demodulator::getQuantizationEma()
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{
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return qnt_ema;
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}
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float M17Demodulator::getQuantizationMax()
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{
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return qnt_max;
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}
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float M17Demodulator::getQuantizationMin()
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{
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return qnt_min;
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}
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int32_t M17Demodulator::convolution(int32_t offset,
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int8_t *target,
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size_t target_size)
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@ -199,15 +178,14 @@ sync_t M17Demodulator::nextFrameSync(int32_t offset)
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#ifdef PLATFORM_LINUX
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FILE *csv_log = fopen("demod_log_1.csv", "a");
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#endif
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sync_t syncword = { -1, false };
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// Find peaks in the correlation between the baseband and the frame syncword
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// Leverage the fact LSF syncword is the opposite of the frame syncword
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// to detect both syncwords at once. Stop early because convolution needs
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// access samples ahead of the starting offset.
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for(int32_t i = offset;
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syncword.index == -1 &&
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i < (int32_t) baseband.len - (int32_t) M17_BRIDGE_SIZE;
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i++)
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int32_t maxLen = static_cast < int32_t >(baseband.len - M17_BRIDGE_SIZE);
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for(int32_t i = offset; (syncword.index == -1) && (i < maxLen); i++)
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{
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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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@ -218,28 +196,31 @@ sync_t M17Demodulator::nextFrameSync(int32_t offset)
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sample = basebandBridge[M17_BRIDGE_SIZE + i];
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else // Otherwise use regular data buffer
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sample = baseband.data[i];
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#ifdef PLATFORM_LINUX
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fprintf(csv_log, "%" PRId16 ",%d,%f,%d\n",
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sample,
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conv - (int32_t) getCorrelationEma(),
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conv - static_cast< int32_t >(conv_ema),
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conv_threshold_factor * getCorrelationStddev(),
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i);
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#endif
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// Positive correlation peak -> frame syncword
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if (conv - (int32_t) getCorrelationEma() >
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getCorrelationStddev() * conv_threshold_factor)
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if ((conv - static_cast< int32_t >(conv_ema)) >
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(getCorrelationStddev() * conv_threshold_factor))
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{
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syncword.lsf = false;
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syncword.index = i;
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}
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// Negative correlation peak -> LSF syncword
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else if (conv - (int32_t) getCorrelationEma() <
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else if ((conv - static_cast< int32_t >(conv_ema)) <
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-(getCorrelationStddev() * conv_threshold_factor))
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{
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syncword.lsf = true;
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syncword.index = i;
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}
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}
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#ifdef PLATFORM_LINUX
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fclose(csv_log);
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#endif
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@ -254,10 +235,10 @@ int8_t M17Demodulator::quantize(int32_t offset)
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else // Otherwise use regular data buffer
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sample = baseband.data[offset];
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// DC offset removal
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int16_t s = sample - (int16_t) getQuantizationEma();
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if (s > getQuantizationMax() / 2)
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int16_t s = sample - static_cast< int16_t >(qnt_ema);
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if (s > static_cast< int16_t >(qnt_max) / 2)
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return +3;
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else if (s < getQuantizationMin() / 2)
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else if (s < static_cast< int16_t >(qnt_min) / 2)
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return -3;
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else if (s > 0)
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return +1;
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@ -287,8 +268,10 @@ bool M17Demodulator::update()
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M17::sync_t syncword = { 0, false };
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int32_t offset = locked ? 0 : -(int32_t) M17_BRIDGE_SIZE;
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uint16_t decoded_syms = 0;
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// Read samples from the ADC
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baseband = inputStream_getData(basebandId);
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#ifdef PLATFORM_LINUX
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FILE *csv_log = fopen("demod_log_2.csv", "a");
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#endif
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@ -301,16 +284,12 @@ bool M17Demodulator::update()
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{
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float elem = static_cast< float >(baseband.data[i]);
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baseband.data[i] = static_cast< int16_t >(M17::rrc(elem));
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//samples_fifo.push_back(baseband.data[i]);
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//if (samples_fifo.size() > SCREEN_WIDTH)
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// samples_fifo.pop_front();
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}
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// Process the buffer
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while(syncword.index != -1 &&
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(offset + phase +
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(int32_t) M17_SAMPLES_PER_SYMBOL * decoded_syms <
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(int32_t) baseband.len))
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int32_t symbol_index = 0;
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while((syncword.index != -1) &&
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(symbol_index < static_cast< int32_t > (baseband.len)))
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{
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// If we are not locked search for a syncword
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if (!locked)
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@ -319,7 +298,7 @@ bool M17Demodulator::update()
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if (syncword.index != -1) // Lock was just acquired
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{
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locked = true;
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isLSF = syncword.lsf;
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isLSF = syncword.lsf;
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offset = syncword.index + 1;
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frameIndex = 0;
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}
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@ -328,9 +307,13 @@ bool M17Demodulator::update()
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else
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{
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// Slice the input buffer to extract a frame and quantize
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int32_t symbol_index = offset + phase + M17_SAMPLES_PER_SYMBOL * decoded_syms;
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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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int8_t symbol = quantize(symbol_index);
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#ifdef PLATFORM_LINUX
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fprintf(csv_log, "%" PRId16 ",%f,%f,%d,%d\n",
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baseband.data[symbol_index] - (int16_t) qnt_ema,
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@ -339,6 +322,7 @@ bool M17Demodulator::update()
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symbol * 666,
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frameIndex == 0 ? 2300 : symbol_index);
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#endif
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setSymbol<M17_FRAME_BYTES>(*activeFrame, frameIndex, symbol);
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decoded_syms++;
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frameIndex++;
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@ -349,27 +333,27 @@ bool M17Demodulator::update()
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std::swap(activeFrame, idleFrame);
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frameIndex = 0;
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newFrame = true;
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// DEBUG: print idleFrame bytes
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for(size_t i = 0; i < idleFrame->size(); i+=2)
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{
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if (i % 16 == 14)
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printf("\r\n");
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printf(" %02X%02X", (*idleFrame)[i], (*idleFrame)[i+1]);
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}
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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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(hammingDistance((*activeFrame)[0], stream_syncword_bytes[0]) +
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hammingDistance((*activeFrame)[1], stream_syncword_bytes[1]) > 2) &&
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(hammingDistance((*activeFrame)[0], lsf_syncword_bytes[0]) +
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hammingDistance((*activeFrame)[1], lsf_syncword_bytes[1]) > 2))
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(hammingSync > 2) && (hammingLsf > 2))
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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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newFrame = true;
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#ifdef PLATFORM_MOD17
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gpio_clearPin(SYNC_LED);
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#endif // PLATFORM_MOD17
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@ -398,12 +382,10 @@ bool M17Demodulator::update()
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sizeof(int16_t) * M17_BRIDGE_SIZE);
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}
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}
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//gfx_plotData({0, 0}, SCREEN_WIDTH, SCREEN_HEIGHT, samples_fifo);
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#ifdef PLATFORM_LINUX
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fclose(csv_log);
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#endif
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return newFrame;
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}
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} /* M17 */
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