Add M17 demodulator code and tests
Added implementation of the M17 4FSK demodulator, including clock recovery, phase detection, and quantization algorithms. A testsuite is also included to do regression testing against a reference baseband pre-generated and the corresponding reference bitstream. A 1% BER is still present due to a fault likely in the RRC filtering, since the eye diagram of the filtered stream is bad. TG-81
This commit is contained in:
Niccolò Izzo
Silvano Seva
parent
396f66a1f3
commit
3163dd49d7
11
meson.build
11
meson.build
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@ -42,6 +42,7 @@ openrtx_src = ['openrtx/src/core/state.c',
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'openrtx/src/protocols/M17/M17DSP.cpp',
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'openrtx/src/protocols/M17/M17Callsign.cpp',
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'openrtx/src/protocols/M17/M17Modulator.cpp',
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'openrtx/src/protocols/M17/M17Demodulator.cpp',
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'openrtx/src/protocols/M17/M17Transmitter.cpp',
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'openrtx/src/protocols/M17/M17LinkSetupFrame.cpp']
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@ -614,5 +615,15 @@ m17_viterbi_test = executable('m17_viterbi_test',
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sources : unit_test_src + ['tests/unit/M17_viterbi.cpp'],
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kwargs : unit_test_opts)
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m17_demodulator_test = executable('m17_demodulator_test',
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sources: unit_test_src + ['tests/unit/M17_demodulator.cpp'],
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kwargs: unit_test_opts)
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m17_rrc_test = executable('m17_rrc_test',
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sources: unit_test_src + ['tests/unit/M17_rrc.cpp'],
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kwargs: unit_test_opts)
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test('M17 Golay Unit Test', m17_golay_test)
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test('M17 Viterbi Unit Test', m17_viterbi_test)
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test('M17 Demodulator Test', m17_demodulator_test)
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test('M17 RRC Test', m17_rrc_test)
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@ -27,9 +27,20 @@
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#error This header is C++ only!
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#endif
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#include <array>
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#include <cstdint>
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#include <cstddef>
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#include <interfaces/audio_stream.h>
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#include <hwconfig.h>
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namespace M17
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{
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typedef struct {
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int32_t index;
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bool lsf;
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} sync_t;
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class M17Demodulator
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{
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public:
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@ -65,34 +76,138 @@ public:
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void stopBasebandSampling();
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/**
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* Returns the next frame decoded from the baseband signal
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* Returns the a frame decoded from the baseband signal.
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*/
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const std::array<uint8_t, 48>& nextFrame();
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const std::array<uint8_t, 48> &getFrame();
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};
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/**
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* Returns a flag indicating whether the decoded frame is an LSF.
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*/
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bool isFrameLSF();
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/**
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* Demodulates data from the ADC and fills the idle frame
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* Everytime this function is called a whole ADC buffer is consumed
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*/
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void update();
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private:
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/**
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* M17 syncword symbols after RRC sampled at 5 samples per symbol;
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/*
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* We are sampling @ 24KHz so an M17 frame has half the samples,
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* our input buffer contains half M17 frame.
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*/
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uint8_t syncword[] = { };
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// TODO: Select correct RRC filter according to sample rate
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static constexpr size_t M17_RX_SAMPLE_RATE = 24000;
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static constexpr size_t M17_FRAME_SAMPLES_24K = 960;
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static constexpr size_t M17_FRAME_SYMBOLS = 192;
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static constexpr size_t M17_SYNCWORD_SYMBOLS = 8;
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static constexpr size_t M17_CONV_THRESHOLD = 50000;
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static constexpr size_t M17_SAMPLES_PER_SYMBOL = M17_SPS;
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static constexpr size_t M17_INPUT_BUF_SIZE = M17_FRAME_SAMPLES_24K / 2;
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static constexpr size_t M17_FRAME_BYTES = M17_FRAME_SYMBOLS / 4;
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static constexpr float conv_stats_alpha = 0.0009765625f;
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static constexpr float conv_threshold_factor = 3.65;
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static constexpr float qnt_maxmin_alpha = 0.999f;
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using dataBuffer_t = std::array< int16_t, M17_FRAME_SAMPLES >;
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using dataFrame_t = std::array< int8_t, M17_FRAME_SYMBOLS >;
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/**
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* M17 syncwords;
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*/
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int8_t lsf_syncword[M17_SYNCWORD_SYMBOLS] = { +3, +3, +3, +3, -3, -3, +3, -3 };
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int8_t stream_syncword[M17_SYNCWORD_SYMBOLS] = { -3, -3, -3, -3, +3, +3, -3, +3 };
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using dataBuffer_t = std::array< int16_t, M17_FRAME_SAMPLES_24K >;
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using dataFrame_t = std::array< uint8_t, M17_FRAME_BYTES >;
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/*
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* Buffers
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*/
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streamId basebandId; ///< Id of the baseband input stream.
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int16_t *baseband_buffer; ///< Buffer for baseband audio handling.
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dataBuffer_t *activeBuffer; ///< Half baseband buffer, in reception.
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dataBuffer_t *idleBuffer; ///< Half baseband buffer, to be processed.
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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 rawFrameIndex; ///< Index for filling the raw frame.
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dataFrame_t *activeFrame; ///< Half frame, in demodulation.
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dataFrame_t *idleFrame; ///< Half frame, free to be processed.
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bool isLSF; ///< Indicates that we demodualated an LSF.
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bool locked; ///< A syncword was detected.
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/*
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* State variables
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*/
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bool m17RxEnabled; ///< M17 Reception Enabled
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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_emvar = 0.0f;
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/*
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* Quantization statistics computation
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*/
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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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* Finds the index of the next syncword in the baseband stream.
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* Resets the exponential mean and variance/stddev computation.
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*/
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void resetCorrelationStats();
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/**
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* Updates the mean and variance with the given value.
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*
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* @param value: value to be added to the exponential moving
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* average/variance computation
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*/
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void updateCorrelationStats(int32_t value);
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/**
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* Returns the standard deviation from all the passed values.
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*
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* @returns float numerical value of the standard deviation
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*/
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float getCorrelationStddev();
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void resetQuantizationStats();
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void updateQuantizationStats(uint32_t offset);
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float getQuantizationMax();
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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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*
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* @param offset: the offset in the active buffer where to start the stride
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* @param target: a buffer containing the target waveform to be convoluted
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* @param target_size: the number of symbols of the target waveform
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* @return uint16_t numerical value of the convolution
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*/
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int32_t convolution(size_t offset, int8_t *target, size_t target_size);
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/**
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* Finds the index of the next frame syncword in the baseband stream.
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*
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* @param baseband: buffer containing the sampled baseband signal
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* @param offset: offset of the buffer after which syncword are searched
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* @return uint16_t index of the first syncword in the buffer after the offset
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*/ uint16_t nextSyncWord(int16_t *baseband);
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*/
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sync_t nextFrameSync(uint32_t offset);
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/**
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* Takes the value from the input baseband at a given offsets and quantizes
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* it leveraging the quantization max and min hold statistics.
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*
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* @param offset: the offset in the input baseband
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* @return int8_t quantized symbol
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*/
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int8_t quantize(int32_t offset);
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};
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} /* M17 */
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#endif /* M17_DEMODULATOR_H */
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@ -29,6 +29,7 @@
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#include <cstddef>
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#include <cstdint>
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#include <array>
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#include <assert.h>
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/**
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@ -69,4 +70,40 @@ inline void setBit(std::array< uint8_t, N >& array, const size_t pos,
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(bit ? mask : 0x00);
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}
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/**
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* Utility function allowing to set the value of a symbol on an array
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* of bytes. Symbols are packed putting the most significant bit first,
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* symbols are filled from the least significant bit pair to the most
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* significant bit pair.
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*
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* \param array: byte array.
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* \param pos: symbol position inside the array.
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* \param symbol: symbol to be set, either -3, -1, +1, +3.
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*/
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template < size_t N >
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inline void setSymbol(std::array< uint8_t, N >& array, const size_t pos,
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const int8_t symbol)
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{
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switch(symbol) {
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case +3:
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setBit<N> (array, 2 * pos , 0);
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setBit<N> (array, 2 * pos + 1, 1);
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break;
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case +1:
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setBit<N> (array, 2 * pos , 0);
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setBit<N> (array, 2 * pos + 1, 0);
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break;
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case -1:
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setBit<N> (array, 2 * pos , 1);
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setBit<N> (array, 2 * pos + 1, 0);
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break;
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case -3:
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setBit<N> (array, 2 * pos , 1);
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setBit<N> (array, 2 * pos + 1, 1);
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break;
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default:
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assert("Error: storing unknown M17 symbol!");
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}
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}
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#endif /* M17_UTILS_H */
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@ -24,7 +24,7 @@ namespace M17
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{
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/*
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* Coefficients for M17 RRC filter
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* Coefficients for M17 RRC filter for 48KHz sample rate
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*/
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const std::array<float, 79> rrc_taps = {
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-0.009265784007800534, -0.006136551625729697, -0.001125978562075172,
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@ -0,0 +1,247 @@
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/***************************************************************************
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* Copyright (C) 2021 by Federico Amedeo Izzo IU2NUO, *
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* Niccolò Izzo IU2KIN *
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* Frederik Saraci IU2NRO *
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* Silvano Seva IU2KWO *
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* *
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* This program is free software; you can redistribute it and/or modify *
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* it under the terms of the GNU General Public License as published by *
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* the Free Software Foundation; either version 3 of the License, or *
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* (at your option) any later version. *
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* *
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* This program is distributed in the hope that it will be useful, *
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* but WITHOUT ANY WARRANTY; without even the implied warranty of *
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
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* GNU General Public License for more details. *
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* *
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* You should have received a copy of the GNU General Public License *
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* along with this program; if not, see <http://www.gnu.org/licenses/> *
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***************************************************************************/
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#include <M17/M17Demodulator.h>
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#include <M17/M17DSP.h>
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#include <M17/M17Utils.h>
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#include <interfaces/audio_stream.h>
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#include <math.h>
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#if defined(PLATFORM_MD3x0) || defined(PLATFORM_MDUV3x0)
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#include <toneGenerator_MDx.h>
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#elif defined(PLATFORM_LINUX)
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#include <stdio.h>
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#endif
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namespace M17
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{
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M17Demodulator::M17Demodulator()
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{
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}
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M17Demodulator::~M17Demodulator()
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{
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terminate();
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}
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void M17Demodulator::init()
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{
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/*
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* Allocate a chunk of memory to contain two complete buffers for baseband
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* audio. Split this chunk in two separate blocks for double buffering using
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* placement new.
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*/
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baseband_buffer = new int16_t[M17_FRAME_SAMPLES_24K];
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baseband = { nullptr, 0 };
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activeFrame = new dataFrame_t;
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rawFrame = new uint16_t[M17_FRAME_SYMBOLS];
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idleFrame = new dataFrame_t;
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}
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void M17Demodulator::terminate()
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{
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// Delete the buffers and deallocate memory.
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delete[] baseband_buffer;
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delete activeFrame;
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delete[] rawFrame;
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delete idleFrame;
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}
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void M17Demodulator::startBasebandSampling()
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{
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basebandId = inputStream_start(SOURCE_RTX, PRIO_RX,
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baseband_buffer,
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M17_INPUT_BUF_SIZE,
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BUF_CIRC_DOUBLE,
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M17_RX_SAMPLE_RATE);
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}
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void M17Demodulator::stopBasebandSampling()
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{
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inputStream_stop(basebandId);
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}
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void M17Demodulator::resetCorrelationStats() {
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conv_ema = 0.0f;
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conv_emvar = 10000000000.0f;
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}
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/**
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* Algorithms taken from
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* https://fanf2.user.srcf.net/hermes/doc/antiforgery/stats.pdf
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*/
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void M17Demodulator::updateCorrelationStats(int32_t value)
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{
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float delta = (float) value - conv_ema;
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float incr = conv_stats_alpha * delta;
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conv_ema += incr;
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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::getCorrelationStddev()
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{
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return sqrt(conv_emvar);
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}
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void M17Demodulator::resetQuantizationStats() {
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qnt_max = 0.0f;
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}
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void M17Demodulator::updateQuantizationStats(uint32_t offset)
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{
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auto value = baseband.data[offset];
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if (value > qnt_max) {
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qnt_max = value;
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} else
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qnt_max *= qnt_maxmin_alpha;
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if (value < qnt_min) {
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qnt_min = value;
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} else
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qnt_min *= qnt_maxmin_alpha;
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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(size_t offset,
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int8_t *target,
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size_t target_size)
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{
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// Compute convolution
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int32_t conv = 0;
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for(uint32_t i = 0; i < target_size; i++)
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{
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conv += (int32_t) target[i] *
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(int32_t) this->baseband.data[offset + i * M17_SAMPLES_PER_SYMBOL];
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}
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return conv;
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}
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sync_t M17Demodulator::nextFrameSync(uint32_t offset)
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{
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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.
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for(uint32_t i = offset; syncword.index == -1 && i < baseband.len; i++)
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{
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int32_t conv = convolution(i, stream_syncword, M17_SYNCWORD_SYMBOLS);
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updateCorrelationStats(conv);
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// Positive correlation peak -> frame syncword
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if (conv > 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 < -(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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return syncword;
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}
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int8_t M17Demodulator::quantize(int32_t offset)
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{
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if (baseband.data[offset] > getQuantizationMax() * 2 / 3)
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return +3;
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else if (baseband.data[offset] < getQuantizationMin() * 2 / 3)
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return -3;
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else if (baseband.data[offset] > 0)
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return +1;
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else
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return -1;
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}
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const std::array<uint8_t, 48> &M17Demodulator::getFrame()
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{
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return *activeFrame;
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}
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bool M17Demodulator::isFrameLSF()
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{
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return isLSF;
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}
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void M17Demodulator::update()
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{
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// Read samples from the ADC
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baseband = inputStream_getData(basebandId);
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if(baseband.data != NULL)
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{
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// Apply RRC on the baseband buffer
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for(size_t i = 0; i < baseband.len; i++)
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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) * 0.10);
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}
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// If we locked a syncword just demodulate samples
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if (locked)
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{
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}
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else // Otherwise find next syncword
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{
|
||||
M17::sync_t syncword = { -1, false };
|
||||
uint16_t offset = 0;
|
||||
syncword = nextFrameSync(offset);
|
||||
if (syncword.index != -1)
|
||||
{
|
||||
locked = true;
|
||||
// Set a flag to mark LSF
|
||||
isLSF = syncword.lsf;
|
||||
// Next syncword does not overlap with current syncword
|
||||
offset = syncword.index + M17_SAMPLES_PER_SYMBOL;
|
||||
// Slice the input buffer to extract a frame and quantize
|
||||
for(uint16_t i = 0; i < M17_FRAME_SYMBOLS; i++)
|
||||
{
|
||||
// Quantize
|
||||
uint16_t symbol_index = syncword.index + 2 +
|
||||
M17_SAMPLES_PER_SYMBOL * i;
|
||||
updateQuantizationStats(baseband.data[symbol_index]);
|
||||
int8_t symbol = quantize(symbol_index);
|
||||
setSymbol<M17_FRAME_BYTES>(*activeFrame, i, symbol);
|
||||
// If the frame buffer is full switch active and idle frame
|
||||
if (rawFrameIndex == M17_FRAME_SYMBOLS)
|
||||
std::swap(activeFrame, idleFrame);
|
||||
}
|
||||
// If we have some samples left, try to decode the syncword
|
||||
// If decoding fails, signal lock is lost
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
} /* M17 */
|
||||
|
|
@ -139,4 +139,7 @@
|
|||
#define GPS_EN GPIOD,8
|
||||
#define GPS_DATA GPIOD,9
|
||||
|
||||
/* M17 demodulation */
|
||||
#define M17_SPS 5
|
||||
|
||||
#endif
|
||||
|
|
|
|||
|
|
@ -83,4 +83,7 @@
|
|||
#define SOFTPOT_RX 0x2E
|
||||
#define SOFTPOT_TX 0x2F
|
||||
|
||||
/* M17 demodulation */
|
||||
#define M17_SPS 5
|
||||
|
||||
#endif
|
||||
|
|
|
|||
|
|
@ -54,3 +54,6 @@
|
|||
|
||||
/* Push-to-talk switch */
|
||||
#define PTT_SW "PTT_SW",11
|
||||
|
||||
/* M17 demodulation */
|
||||
#define M17_SPS 10
|
||||
|
|
|
|||
|
|
@ -0,0 +1,14 @@
|
|||
#! /usr/bin/env python3
|
||||
|
||||
import pandas as pd
|
||||
from matplotlib import pyplot as plt
|
||||
|
||||
plt.rcParams["figure.autolayout"] = True
|
||||
df = pd.read_csv("./build_linux/M17_clock_recovery_output_1.csv")
|
||||
print("Contents in csv file:\n", df)
|
||||
#plt.plot(df.index, df.Input)
|
||||
#plt.plot(df.index, df.RRCSignal)
|
||||
plt.plot(df.index, df.LSFConvolution)
|
||||
plt.plot(df.index, df.FrameConvolution)
|
||||
plt.plot(df.index, df.Stddev)
|
||||
plt.show()
|
||||
|
|
@ -0,0 +1,14 @@
|
|||
#! /usr/bin/env python3
|
||||
|
||||
import pandas as pd
|
||||
from matplotlib import pyplot as plt
|
||||
|
||||
plt.rcParams["figure.autolayout"] = True
|
||||
df = pd.read_csv("./build_linux/M17_clock_recovery_output_2.csv")
|
||||
print("Contents in csv file:\n", df)
|
||||
plt.plot(df.index, df.RRCSignal)
|
||||
plt.plot(df.index, df.SyncDetect)
|
||||
plt.plot(df.index, df.QntMax)
|
||||
plt.plot(df.index, df.QntMin)
|
||||
plt.plot(df.index, df.Symbol)
|
||||
plt.show()
|
||||
|
|
@ -0,0 +1,237 @@
|
|||
/***************************************************************************
|
||||
* Copyright (C) 2021 by Federico Amedeo Izzo IU2NUO, *
|
||||
* Niccolò Izzo IU2KIN *
|
||||
* Frederik Saraci IU2NRO *
|
||||
* Silvano Seva IU2KWO *
|
||||
* *
|
||||
* *
|
||||
* This program is free software; you can redistribute it and/or modify *
|
||||
* it under the terms of the GNU General Public License as published by *
|
||||
* the Free Software Foundation; either version 3 of the License, or *
|
||||
* (at your option) any later version. *
|
||||
* *
|
||||
* This program is distributed in the hope that it will be useful, *
|
||||
* but WITHOUT ANY WARRANTY; without even the implied warranty of *
|
||||
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
|
||||
* GNU General Public License for more details. *
|
||||
* *
|
||||
* You should have received a copy of the GNU General Public License *
|
||||
* along with this program; if not, see <http://www.gnu.org/licenses/> *
|
||||
***************************************************************************/
|
||||
|
||||
// Test private methods
|
||||
#define private public
|
||||
|
||||
#include <inttypes.h>
|
||||
#include <stdio.h>
|
||||
#include <stdlib.h>
|
||||
#include <string.h>
|
||||
#include <M17/M17DSP.h>
|
||||
#include <M17/M17Demodulator.h>
|
||||
#include <M17/M17Utils.h>
|
||||
#include <interfaces/audio_stream.h>
|
||||
|
||||
using namespace std;
|
||||
|
||||
/**
|
||||
* Test the different demodulation steps
|
||||
*/
|
||||
|
||||
int main()
|
||||
{
|
||||
// Open file
|
||||
FILE *baseband_file = fopen("../tests/unit/assets/M17_test_baseband.raw", "rb");
|
||||
FILE *baseband_out = fopen("M17_test_baseband_rrc.raw", "wb");
|
||||
if (!baseband_file)
|
||||
{
|
||||
perror("Error in reading test baseband");
|
||||
return -1;
|
||||
}
|
||||
|
||||
// Get file size
|
||||
fseek(baseband_file, 0L, SEEK_END);
|
||||
long baseband_size = ftell(baseband_file);
|
||||
unsigned baseband_samples = baseband_size / 2;
|
||||
fseek(baseband_file, 0L, SEEK_SET);
|
||||
printf("Baseband is %ld bytes!\n", baseband_size);
|
||||
|
||||
// Read data from input file
|
||||
int16_t *baseband_buffer = (int16_t *) malloc(baseband_size);
|
||||
if (!baseband_buffer)
|
||||
{
|
||||
perror("Error in memory allocation");
|
||||
return -1;
|
||||
}
|
||||
size_t read_items = fread(baseband_buffer, 2, baseband_samples, baseband_file);
|
||||
if (read_items != baseband_samples)
|
||||
{
|
||||
perror("Error in reading input file");
|
||||
return -1;
|
||||
}
|
||||
fclose(baseband_file);
|
||||
|
||||
// Apply RRC on the baseband buffer
|
||||
int16_t *filtered_buffer = (int16_t *) malloc(baseband_size);
|
||||
for(size_t i = 0; i < baseband_samples; i++)
|
||||
{
|
||||
float elem = static_cast< float >(baseband_buffer[i]);
|
||||
filtered_buffer[i] = static_cast< int16_t >(M17::rrc(0.10 * elem));
|
||||
}
|
||||
fwrite(filtered_buffer, baseband_samples, 2, baseband_out);
|
||||
fclose(baseband_out);
|
||||
|
||||
M17::M17Demodulator m17Demodulator = M17::M17Demodulator();
|
||||
m17Demodulator.init();
|
||||
dataBlock_t baseband = { nullptr, 0 };
|
||||
baseband.data = baseband_buffer;
|
||||
baseband.len = baseband_samples;
|
||||
dataBlock_t old_baseband = m17Demodulator.baseband;
|
||||
m17Demodulator.baseband = baseband;
|
||||
baseband.data = filtered_buffer;
|
||||
|
||||
FILE *output_csv_1 = fopen("M17_clock_recovery_output_1.csv", "w");
|
||||
fprintf(output_csv_1, "Input,RRCSignal,LSFConvolution,FrameConvolution,Stddev\n");
|
||||
// Test convolution
|
||||
m17Demodulator.resetCorrelationStats();
|
||||
for(unsigned i = 0; i < baseband_samples - m17Demodulator.M17_SYNCWORD_SYMBOLS * M17_SPS; i++)
|
||||
{
|
||||
int32_t lsf_conv =
|
||||
m17Demodulator.convolution(i,
|
||||
m17Demodulator.lsf_syncword,
|
||||
m17Demodulator.M17_SYNCWORD_SYMBOLS);
|
||||
int32_t stream_conv =
|
||||
m17Demodulator.convolution(i,
|
||||
m17Demodulator.stream_syncword,
|
||||
m17Demodulator.M17_SYNCWORD_SYMBOLS);
|
||||
m17Demodulator.updateCorrelationStats(stream_conv);
|
||||
fprintf(output_csv_1, "%" PRId16 ",%" PRId16 ",%d,%d,%f\n",
|
||||
baseband_buffer[i],
|
||||
baseband.data[i],
|
||||
lsf_conv,
|
||||
stream_conv,
|
||||
3.65 * m17Demodulator.getCorrelationStddev());
|
||||
}
|
||||
fclose(output_csv_1);
|
||||
|
||||
// Test syncword detection
|
||||
printf("Testing syncword detection!\n");
|
||||
FILE *syncword_ref = fopen("../tests/unit/assets/M17_test_baseband_syncwords.txt", "r");
|
||||
int32_t offset = 0;
|
||||
M17::sync_t syncword = { -1, false };
|
||||
m17Demodulator.resetCorrelationStats();
|
||||
int i = 0;
|
||||
do
|
||||
{
|
||||
int expected_syncword = 0;
|
||||
fscanf(syncword_ref, "%d\n", &expected_syncword);
|
||||
syncword = m17Demodulator.nextFrameSync(offset);
|
||||
offset = syncword.index + m17Demodulator.M17_SYNCWORD_SYMBOLS * M17_SPS;
|
||||
if (syncword.index != expected_syncword)
|
||||
{
|
||||
fprintf(stderr, "Error in syncwords detection #%d!\n", i);
|
||||
return -1;
|
||||
}
|
||||
else
|
||||
{
|
||||
printf("SYNC: %d...OK!\n", syncword.index);
|
||||
}
|
||||
i++;
|
||||
} while (syncword.index != -1);
|
||||
fclose(syncword_ref);
|
||||
|
||||
FILE *output_csv_2 = fopen("M17_clock_recovery_output_2.csv", "w");
|
||||
fprintf(output_csv_2, "RRCSignal,SyncDetect,QntMax,QntMin,Symbol\n");
|
||||
uint32_t detect = 0, symbol = 0;
|
||||
offset = 0;
|
||||
syncword = { -1, false };
|
||||
m17Demodulator.resetCorrelationStats();
|
||||
syncword = m17Demodulator.nextFrameSync(offset);
|
||||
for(unsigned i = 0; i < baseband_samples - m17Demodulator.M17_SYNCWORD_SYMBOLS * M17_SPS; i++)
|
||||
{
|
||||
if ((int) i == syncword.index + 2) {
|
||||
if (syncword.lsf)
|
||||
detect = -40000;
|
||||
else
|
||||
detect = 40000;
|
||||
syncword = m17Demodulator.nextFrameSync(syncword.index + m17Demodulator.M17_SYNCWORD_SYMBOLS * M17_SPS);
|
||||
} else if (((int) i % 10) == ((syncword.index + 2) % 10)) {
|
||||
m17Demodulator.updateQuantizationStats(i);
|
||||
symbol = m17Demodulator.quantize(i) * 10000;
|
||||
detect = 30000;
|
||||
} else
|
||||
{
|
||||
detect = 0;
|
||||
symbol = 0;
|
||||
}
|
||||
fprintf(output_csv_2, "%" PRId16 ",%d,%f,%f,%d\n",
|
||||
m17Demodulator.baseband.data[i],
|
||||
detect,
|
||||
m17Demodulator.getQuantizationMax() * 2 / 3,
|
||||
m17Demodulator.getQuantizationMin() * 2 / 3,
|
||||
symbol);
|
||||
}
|
||||
fclose(output_csv_2);
|
||||
|
||||
// Test symbol quantization
|
||||
FILE *symbols_ref = fopen("../tests/unit/assets/M17_test_baseband.bin", "rb");
|
||||
// Skip preamble
|
||||
fseek(symbols_ref, 0x30, SEEK_SET);
|
||||
uint32_t failed_bytes = 0, total_bytes = 0;
|
||||
syncword = { -1, false };
|
||||
offset = 0;
|
||||
syncword = m17Demodulator.nextFrameSync(offset);
|
||||
std::array< uint8_t, m17Demodulator.M17_FRAME_BYTES > frame;
|
||||
// Preheat quantizer
|
||||
for(int i = 0; i < 10; i++)
|
||||
m17Demodulator.updateQuantizationStats(i);
|
||||
if (syncword.index != -1)
|
||||
{
|
||||
// Next syncword does not overlap with current syncword
|
||||
offset = syncword.index + m17Demodulator.M17_SAMPLES_PER_SYMBOL;
|
||||
// Slice the input buffer to extract a frame and quantize
|
||||
for(uint32_t j = 0;
|
||||
syncword.index + 2 + m17Demodulator.M17_SAMPLES_PER_SYMBOL * (j + i) < m17Demodulator.baseband.len;
|
||||
j+= m17Demodulator.M17_FRAME_SYMBOLS)
|
||||
{
|
||||
for(uint16_t i = 0; i < m17Demodulator.M17_FRAME_SYMBOLS; i++)
|
||||
{
|
||||
// Quantize
|
||||
uint32_t symbol_index = syncword.index + 2 +
|
||||
m17Demodulator.M17_SAMPLES_PER_SYMBOL * (j + i);
|
||||
m17Demodulator.updateQuantizationStats(symbol_index);
|
||||
int8_t symbol = m17Demodulator.quantize(symbol_index);
|
||||
setSymbol<m17Demodulator.M17_FRAME_BYTES>(frame, i, symbol);
|
||||
}
|
||||
for(uint16_t i = 0; i < m17Demodulator.M17_FRAME_BYTES; i+=2) {
|
||||
if (i % 16 == 0)
|
||||
printf("\n");
|
||||
printf(" %02X%02X", frame[i], frame[i+1]);
|
||||
// Check with reference bitstream
|
||||
uint8_t ref_byte = 0x00;
|
||||
fread(&ref_byte, 1, 1, symbols_ref);
|
||||
if (frame[i] != ref_byte)
|
||||
{
|
||||
printf("Mismatch byte #%u!\n", i);
|
||||
failed_bytes++;
|
||||
}
|
||||
fread(&ref_byte, 1, 1, symbols_ref);
|
||||
if (frame[i+1] != ref_byte)
|
||||
{
|
||||
printf("Mismatch byte #%u!\n", i);
|
||||
failed_bytes++;
|
||||
}
|
||||
total_bytes += 1;
|
||||
}
|
||||
printf("\n");
|
||||
}
|
||||
}
|
||||
printf("Failed decoding %d/%d bytes!\n", failed_bytes, total_bytes);
|
||||
|
||||
// TODO: keep aside end of last buffer and use at beginning of the next buffer
|
||||
// TODO: when stream is over pad with zeroes to avoid corrupting the last symbols
|
||||
|
||||
m17Demodulator.baseband = old_baseband;
|
||||
free(baseband_buffer);
|
||||
free(filtered_buffer);
|
||||
return 0;
|
||||
}
|
||||
|
|
@ -0,0 +1,59 @@
|
|||
/***************************************************************************
|
||||
* Copyright (C) 2021 by Federico Amedeo Izzo IU2NUO, *
|
||||
* Niccolò Izzo IU2KIN *
|
||||
* Frederik Saraci IU2NRO *
|
||||
* Silvano Seva IU2KWO *
|
||||
* *
|
||||
* *
|
||||
* This program is free software; you can redistribute it and/or modify *
|
||||
* it under the terms of the GNU General Public License as published by *
|
||||
* the Free Software Foundation; either version 3 of the License, or *
|
||||
* (at your option) any later version. *
|
||||
* *
|
||||
* This program is distributed in the hope that it will be useful, *
|
||||
* but WITHOUT ANY WARRANTY; without even the implied warranty of *
|
||||
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
|
||||
* GNU General Public License for more details. *
|
||||
* *
|
||||
* You should have received a copy of the GNU General Public License *
|
||||
* along with this program; if not, see <http://www.gnu.org/licenses/> *
|
||||
***************************************************************************/
|
||||
|
||||
#include <limits.h>
|
||||
#include <inttypes.h>
|
||||
#include <stdio.h>
|
||||
#include <M17/M17DSP.h>
|
||||
|
||||
#define IMPULSE_SIZE 4096
|
||||
|
||||
using namespace std;
|
||||
|
||||
/**
|
||||
* Test the different demodulation steps
|
||||
*/
|
||||
|
||||
int main()
|
||||
{
|
||||
// Open file
|
||||
FILE *baseband_out = fopen("M17_rrc_impulse_response.raw", "wb");
|
||||
if (!baseband_out)
|
||||
{
|
||||
perror("Error in opening output file");
|
||||
return -1;
|
||||
}
|
||||
|
||||
// Allocate impulse signal
|
||||
int16_t impulse[IMPULSE_SIZE] = { 0 };
|
||||
impulse[0] = SHRT_MAX;
|
||||
|
||||
// Apply RRC on impulse signal
|
||||
int16_t filtered_impulse[IMPULSE_SIZE] = { 0 };
|
||||
for(size_t i = 0; i < IMPULSE_SIZE; i++)
|
||||
{
|
||||
float elem = static_cast< float >(impulse[i]);
|
||||
filtered_impulse[i] = static_cast< int16_t >(M17::rrc(0.10 * elem));
|
||||
}
|
||||
fwrite(filtered_impulse, IMPULSE_SIZE, 1, baseband_out);
|
||||
fclose(baseband_out);
|
||||
return 0;
|
||||
}
|
||||
Binary file not shown.
Binary file not shown.
|
|
@ -0,0 +1,500 @@
|
|||
1956
|
||||
3876
|
||||
5797
|
||||
7717
|
||||
9637
|
||||
10718
|
||||
11557
|
||||
13158
|
||||
13477
|
||||
15397
|
||||
17318
|
||||
19237
|
||||
21157
|
||||
23077
|
||||
24997
|
||||
26109
|
||||
26917
|
||||
28837
|
||||
29618
|
||||
30757
|
||||
32677
|
||||
34597
|
||||
36517
|
||||
37258
|
||||
38437
|
||||
40357
|
||||
42277
|
||||
44197
|
||||
46117
|
||||
48037
|
||||
49957
|
||||
51877
|
||||
53797
|
||||
55718
|
||||
57637
|
||||
59557
|
||||
61477
|
||||
63397
|
||||
65317
|
||||
67237
|
||||
69157
|
||||
71077
|
||||
72998
|
||||
74918
|
||||
76837
|
||||
78757
|
||||
80677
|
||||
82597
|
||||
84517
|
||||
86437
|
||||
88357
|
||||
90277
|
||||
92197
|
||||
94117
|
||||
96037
|
||||
97957
|
||||
99877
|
||||
101797
|
||||
103716
|
||||
105637
|
||||
106839
|
||||
107557
|
||||
109477
|
||||
111397
|
||||
113316
|
||||
115237
|
||||
117157
|
||||
119077
|
||||
120997
|
||||
122917
|
||||
124837
|
||||
126757
|
||||
127859
|
||||
128677
|
||||
130597
|
||||
132517
|
||||
134437
|
||||
136357
|
||||
138277
|
||||
140197
|
||||
142117
|
||||
144037
|
||||
145957
|
||||
147878
|
||||
149797
|
||||
151717
|
||||
153637
|
||||
155557
|
||||
157477
|
||||
159397
|
||||
160288
|
||||
161317
|
||||
163237
|
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178597
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180377
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491557
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493477
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495397
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497317
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499237
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501158
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503077
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506917
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508837
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510757
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512677
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514597
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516517
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518437
|
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520357
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522278
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524197
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526117
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527028
|
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528037
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529957
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531877
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533797
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537637
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539557
|
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541477
|
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543397
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545318
|
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547237
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549157
|
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551077
|
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552997
|
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554917
|
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556837
|
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558757
|
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560677
|
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562597
|
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564517
|
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566437
|
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568357
|
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570277
|
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572197
|
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574117
|
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576037
|
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577957
|
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579877
|
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581797
|
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583717
|
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585637
|
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587557
|
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589477
|
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591397
|
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593317
|
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595237
|
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597157
|
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599077
|
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600997
|
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602917
|
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604837
|
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606757
|
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608676
|
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610597
|
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612517
|
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614437
|
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616358
|
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618277
|
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620197
|
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622117
|
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624037
|
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625957
|
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627457
|
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627877
|
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629797
|
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631717
|
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633637
|
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635557
|
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637477
|
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639397
|
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639599
|
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641317
|
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643237
|
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645157
|
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647077
|
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648997
|
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650917
|
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652837
|
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654757
|
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656677
|
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658597
|
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660516
|
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662437
|
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664357
|
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666277
|
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668197
|
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670117
|
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672037
|
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673957
|
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675878
|
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677797
|
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679716
|
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681637
|
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683557
|
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685477
|
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687397
|
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689316
|
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691236
|
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693157
|
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695078
|
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696996
|
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698917
|
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700837
|
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702757
|
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704677
|
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706597
|
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708517
|
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708649
|
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709738
|
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710437
|
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712357
|
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714277
|
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716197
|
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718117
|
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720037
|
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721957
|
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723877
|
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725797
|
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727717
|
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729637
|
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731558
|
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733477
|
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735397
|
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737317
|
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739237
|
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741157
|
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|
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744997
|
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746917
|
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748837
|
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750756
|
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752677
|
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754597
|
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756517
|
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758437
|
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760357
|
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762276
|
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764197
|
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766117
|
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768037
|
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769958
|
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771878
|
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773797
|
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775717
|
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777637
|
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779556
|
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781477
|
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783397
|
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785317
|
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787237
|
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789157
|
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791077
|
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792997
|
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794917
|
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796837
|
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798757
|
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800677
|
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802597
|
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804517
|
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806437
|
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808357
|
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810277
|
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812198
|
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814117
|
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816037
|
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817957
|
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819877
|
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821797
|
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823717
|
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825637
|
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827557
|
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829477
|
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831397
|
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833317
|
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835237
|
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837157
|
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838878
|
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839077
|
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840997
|
||||
842917
|
||||
844837
|
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846757
|
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848677
|
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850597
|
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852517
|
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854437
|
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856357
|
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858277
|
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860197
|
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862118
|
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864037
|
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865958
|
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867876
|
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869797
|
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871717
|
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873637
|
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875557
|
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877477
|
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879397
|
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881317
|
||||
883237
|
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885157
|
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887077
|
||||
888997
|
||||
890917
|
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892837
|
||||
894757
|
||||
896677
|
||||
898597
|
||||
900517
|
||||
902438
|
||||
904357
|
||||
905688
|
||||
906276
|
||||
-1
|
||||
Loading…
Reference in New Issue