99 lines
3.4 KiB
C++
99 lines
3.4 KiB
C++
/***************************************************************************
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* Copyright (C) 2021 by Federico Amedeo Izzo IU2NUO, *
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* Niccolò Izzo IU2KIN *
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* Wojciech Kaczmarski SP5WWP *
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* Frederik Saraci IU2NRO *
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* Silvano Seva IU2KWO *
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* *
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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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#ifndef M17_DEMODULATOR_H
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#define M17_DEMODULATOR_H
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#ifndef __cplusplus
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#error This header is C++ only!
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#endif
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namespace M17
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{
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class M17Demodulator
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{
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public:
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/**
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* Constructor.
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*/
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M17Demodulator();
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/**
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* Destructor.
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*/
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~M17Demodulator();
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/**
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* Allocate buffers for baseband signal sampling and initialise demodulator.
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*/
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void init();
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/**
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* Shutdown modulator and deallocate data buffers.
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*/
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void terminate();
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/**
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* Starts the sampling of the baseband signal in a double buffer.
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*/
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void startBasebandSampling();
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/**
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* Stops the sampling of the baseband signal in a double buffer.
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*/
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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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*/
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const std::array<uint8_t, 48>& nextFrame();
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};
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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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uint8_t syncword[] = { };
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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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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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dataFrame_t *activeFrame; ///< Half frame, in demodulation.
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dataFrame_t *idleFrame; ///< Half frame, free to be processed.
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/**
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* Finds the index of the next 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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#endif /* M17_DEMODULATOR_H */
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