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M17 transmitter class

This commit is contained in:
Silvano Seva 2021-08-23 19:10:42 +02:00
parent 39e41ee470
commit 98e4164f54
2 changed files with 214 additions and 0 deletions
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openrtx/include/protocols/M17/M17Transmitter.h Normal file
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/***************************************************************************
* 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/> *
***************************************************************************/
#ifndef M17TRANSMITTER_H
#define M17TRANSMITTER_H
#ifndef __cplusplus
#error This header is C++ only!
#endif
#include <string>
#include <array>
#include "M17ConvolutionalEncoder.h"
#include "M17LinkSetupFrame.h"
#include "M17Frame.h"
#include "M17Modulator.h"
/**
* M17 transmitter.
*/
class M17Transmitter
{
public:
/**
* Constructor.
*
* @param modulator: reference to M17 4FSK modulator driver.
*/
M17Transmitter(M17Modulator& modulator);
/**
* Destructor.
*/
~M17Transmitter();
/**
* Start a new data stream with broadcast destination callsign.
*
* @param src: source callsign.
*/
void start(const std::string& src);
/**
* Start a new data stream with given destination callsign. If destination
* callsing is empty, the stream falls back to broadcast transmission.
*
* @param src: source callsign.
* @param dst: destination callsign.
*/
void start(const std::string& src, const std::string& dst);
/**
* Send a block of data.
*
* @param payload: payload data.
* @param isLast: if true, current frame is marked as the last one to be
* transmitted.
*/
void send(const payload_t& payload, const bool isLast = false);
private:
M17ConvolutionalEncoder encoder; ///< Convolutional encoder.
M17LinkSetupFrame lsf; ///< Link Setup Frame handler.
M17Frame dataFrame; ///< Data frame Handler.
M17Modulator& modulator; ///< 4FSK modulator.
std::array< lich_t, 6 > lichSegments; ///< Encoded LSF chunks for LICH generation.
uint8_t currentLich; ///< Index of current LSF chunk.
uint16_t frameNumber; ///< Current frame number.
};
#endif /* M17TRANSMITTER_H */

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openrtx/src/protocols/M17/M17Transmitter.cpp Normal file
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/***************************************************************************
* 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 <M17/M17CodePuncturing.h>
#include <M17/M17Decorrelator.h>
#include <M17/M17Interleaver.h>
#include <M17/M17Transmitter.h>
static constexpr std::array<uint8_t, 2> LSF_SYNC_WORD = {0x55, 0xF7};
static constexpr std::array<uint8_t, 2> DATA_SYNC_WORD = {0xFF, 0x5D};
M17Transmitter::M17Transmitter(M17Modulator& modulator) : modulator(modulator),
currentLich(0), frameNumber(0)
{
}
M17Transmitter::~M17Transmitter()
{
}
void M17Transmitter::start(const std::string& src)
{
// Just call start() with an empty string for destination callsign.
std::string empty;
start(src, empty);
}
void M17Transmitter::start(const std::string& src, const std::string& dst)
{
// Reset LICH and frame counters
currentLich = 0;
frameNumber = 0;
// Fill the Link Setup Frame
lsf.clear();
lsf.setSource(src);
if(!dst.empty()) lsf.setDestination(dst);
streamType_t type;
type.stream = 1; // Stream
type.dataType = 2; // Voice data
type.CAN = 0xA; // Channel access number
lsf.setType(type);
lsf.updateCrc();
// Generate the Golay(24,12) LICH segments
for(size_t i = 0; i < lichSegments.size(); i++)
{
lichSegments[i] = lsf.generateLichSegment(i);
}
// Encode the LSF, then puncture and decorrelate its data
std::array<uint8_t, 61> encoded;
encoder.reset();
encoder.encode(&lsf.getData(), encoded.data(), sizeof(lsf_t));
encoded[60] = encoder.flush();
std::array<uint8_t, 46> punctured;
puncture(encoded, punctured, LSF_puncture);
interleave(punctured);
decorrelate(punctured);
// Send preamble
std::array<uint8_t, 2> preamble_sync;
std::array<uint8_t, 46> preamble_bytes;
preamble_sync.fill(0x77);
preamble_bytes.fill(0x77);
modulator.send(preamble_sync, preamble_bytes);
// Send LSF
modulator.send(LSF_SYNC_WORD, punctured);
}
void M17Transmitter::send(const payload_t& payload, const bool isLast)
{
dataFrame.clear();
dataFrame.setFrameNumber(frameNumber);
frameNumber = (frameNumber + 1) & 0x07FF;
if(isLast) dataFrame.lastFrame();
std::copy(payload.begin(), payload.end(), dataFrame.payload().begin());
// Encode frame
std::array<uint8_t, 37> encoded;
encoder.reset();
encoder.encode(&dataFrame.getData(), encoded.data(), sizeof(dataFrame_t));
encoded[36] = encoder.flush();
std::array<uint8_t, 34> punctured;
puncture(encoded, punctured, Audio_puncture);
// Add LICH segment to coded data and send
std::array<uint8_t, 46> frame;
auto it = std::copy(lichSegments[currentLich].begin(),
lichSegments[currentLich].end(),
frame.begin());
std::copy(punctured.begin(), punctured.end(), it);
// Increment LICH counter after copy
currentLich = (currentLich + 1) % lichSegments.size();
interleave(frame);
decorrelate(frame);
modulator.send(DATA_SYNC_WORD, frame);
}