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gnss-sdr/src/algorithms/libs/gps_l5_signal.cc

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/*!
* \file gps_l5_signal.cc
* \brief This class implements signal generators for the GPS L5 signals
* \author Javier Arribas, 2017. jarribas(at)cttc.es
*
* Detailed description of the file here if needed.
*
* -------------------------------------------------------------------------
*
* Copyright (C) 2010-2018 (see AUTHORS file for a list of contributors)
*
* GNSS-SDR is a software defined Global Navigation
* Satellite Systems receiver
*
* This file is part of GNSS-SDR.
*
* GNSS-SDR 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.
*
* GNSS-SDR 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 GNSS-SDR. If not, see <https://www.gnu.org/licenses/>.
*
* -------------------------------------------------------------------------
*/
#include "gps_l5_signal.h"
#include "GPS_L5.h"
#include <cinttypes>
#include <cmath>
#include <complex>
#include <deque>
std::deque<bool> l5i_xa_shift(std::deque<bool> xa)
{
if (xa == std::deque<bool>{true, true, true, true, true, true, true, true, true, true, true, false, true})
{
return std::deque<bool>{true, true, true, true, true, true, true, true, true, true, true, true, true};
}
std::deque<bool> out(xa.begin(), xa.end() - 1);
out.push_front(xa[12] xor xa[11] xor xa[9] xor xa[8]);
return out;
}
std::deque<bool> l5q_xa_shift(std::deque<bool> xa)
{
if (xa == std::deque<bool>{true, true, true, true, true, true, true, true, true, true, true, false, true})
{
return std::deque<bool>{true, true, true, true, true, true, true, true, true, true, true, true, true};
}
std::deque<bool> out(xa.begin(), xa.end() - 1);
out.push_front(xa[12] xor xa[11] xor xa[9] xor xa[8]);
return out;
}
std::deque<bool> l5i_xb_shift(std::deque<bool> xb)
{
std::deque<bool> out(xb.begin(), xb.end() - 1);
out.push_front(xb[12] xor xb[11] xor xb[7] xor xb[6] xor xb[5] xor xb[3] xor xb[2] xor xb[0]);
return out;
}
std::deque<bool> l5q_xb_shift(std::deque<bool> xb)
{
std::deque<bool> out(xb.begin(), xb.end() - 1);
out.push_front(xb[12] xor xb[11] xor xb[7] xor xb[6] xor xb[5] xor xb[3] xor xb[2] xor xb[0]);
return out;
}
std::deque<bool> make_l5i_xa()
{
std::deque<bool> xa = {true, true, true, true, true, true, true, true, true, true, true, true, true};
std::deque<bool> y(GPS_L5I_CODE_LENGTH_CHIPS, false);
for (int32_t i = 0; i < GPS_L5I_CODE_LENGTH_CHIPS; i++)
{
y[i] = xa[12];
xa = l5i_xa_shift(xa);
}
return y;
}
std::deque<bool> make_l5i_xb()
{
std::deque<bool> xb = {true, true, true, true, true, true, true, true, true, true, true, true, true};
std::deque<bool> y(GPS_L5I_CODE_LENGTH_CHIPS, false);
for (int32_t i = 0; i < GPS_L5I_CODE_LENGTH_CHIPS; i++)
{
y[i] = xb[12];
xb = l5i_xb_shift(xb);
}
return y;
}
std::deque<bool> make_l5q_xa()
{
std::deque<bool> xa = {true, true, true, true, true, true, true, true, true, true, true, true, true};
std::deque<bool> y(GPS_L5Q_CODE_LENGTH_CHIPS, false);
for (int32_t i = 0; i < GPS_L5Q_CODE_LENGTH_CHIPS; i++)
{
y[i] = xa[12];
xa = l5q_xa_shift(xa);
}
return y;
}
std::deque<bool> make_l5q_xb()
{
std::deque<bool> xb = {true, true, true, true, true, true, true, true, true, true, true, true, true};
std::deque<bool> y(GPS_L5Q_CODE_LENGTH_CHIPS, false);
for (int32_t i = 0; i < GPS_L5Q_CODE_LENGTH_CHIPS; i++)
{
y[i] = xb[12];
xb = l5q_xb_shift(xb);
}
return y;
}
void make_l5i(int32_t* _dest, int32_t prn)
{
int32_t xb_offset = GPS_L5I_INIT_REG[prn];
std::deque<bool> xb = make_l5i_xb();
std::deque<bool> xa = make_l5i_xa();
std::deque<bool> xb_shift(GPS_L5I_CODE_LENGTH_CHIPS, false);
for (int32_t n = 0; n < GPS_L5I_CODE_LENGTH_CHIPS; n++)
{
xb_shift[n] = xb[(xb_offset + n) % GPS_L5I_CODE_LENGTH_CHIPS];
}
std::deque<bool> out_code(GPS_L5I_CODE_LENGTH_CHIPS, false);
for (int32_t n = 0; n < GPS_L5I_CODE_LENGTH_CHIPS; n++)
{
_dest[n] = xa[n] xor xb_shift[n];
}
}
void make_l5q(int32_t* _dest, int32_t prn)
{
int32_t xb_offset = GPS_L5Q_INIT_REG[prn];
std::deque<bool> xb = make_l5q_xb();
std::deque<bool> xa = make_l5q_xa();
std::deque<bool> xb_shift(GPS_L5Q_CODE_LENGTH_CHIPS, false);
for (int32_t n = 0; n < GPS_L5Q_CODE_LENGTH_CHIPS; n++)
{
xb_shift[n] = xb[(xb_offset + n) % GPS_L5Q_CODE_LENGTH_CHIPS];
}
std::deque<bool> out_code(GPS_L5Q_CODE_LENGTH_CHIPS, false);
for (int32_t n = 0; n < GPS_L5Q_CODE_LENGTH_CHIPS; n++)
{
_dest[n] = xa[n] xor xb_shift[n];
}
}
void gps_l5i_code_gen_complex(std::complex<float>* _dest, uint32_t _prn)
{
auto* _code = new int32_t[GPS_L5I_CODE_LENGTH_CHIPS];
if (_prn > 0 and _prn < 51)
{
make_l5i(_code, _prn - 1);
}
for (int32_t i = 0; i < GPS_L5I_CODE_LENGTH_CHIPS; i++)
{
_dest[i] = std::complex<float>(1.0 - 2.0 * _code[i], 0.0);
}
delete[] _code;
}
void gps_l5i_code_gen_float(float* _dest, uint32_t _prn)
{
auto* _code = new int32_t[GPS_L5I_CODE_LENGTH_CHIPS];
if (_prn > 0 and _prn < 51)
{
make_l5i(_code, _prn - 1);
}
for (int32_t i = 0; i < GPS_L5I_CODE_LENGTH_CHIPS; i++)
{
_dest[i] = 1.0 - 2.0 * static_cast<float>(_code[i]);
}
delete[] _code;
}
/*
* Generates complex GPS L5i code for the desired SV ID and sampled to specific sampling frequency
*/
void gps_l5i_code_gen_complex_sampled(std::complex<float>* _dest, uint32_t _prn, int32_t _fs)
{
auto* _code = new int32_t[GPS_L5I_CODE_LENGTH_CHIPS];
if (_prn > 0 and _prn < 51)
{
make_l5i(_code, _prn - 1);
}
int32_t _samplesPerCode, _codeValueIndex;
float _ts;
float _tc;
const int32_t _codeLength = GPS_L5I_CODE_LENGTH_CHIPS;
//--- Find number of samples per spreading code ----------------------------
_samplesPerCode = static_cast<int32_t>(static_cast<double>(_fs) / (static_cast<double>(GPS_L5I_CODE_RATE_HZ) / static_cast<double>(_codeLength)));
//--- Find time constants --------------------------------------------------
_ts = 1.0 / static_cast<float>(_fs); // Sampling period in sec
_tc = 1.0 / static_cast<float>(GPS_L5I_CODE_RATE_HZ); // C/A chip period in sec
//float aux;
for (int32_t i = 0; i < _samplesPerCode; i++)
{
//=== Digitizing =======================================================
//--- Make index array to read L5 code values -------------------------
//TODO: Check this formula! Seems to start with an extra sample
_codeValueIndex = std::ceil((_ts * (static_cast<float>(i) + 1)) / _tc) - 1;
//aux = (_ts * (i + 1)) / _tc;
//_codeValueIndex = static_cast<int32_t> (static_cast<long>(aux)) - 1;
//--- Make the digitized version of the L2C code -----------------------
if (i == _samplesPerCode - 1)
{
//--- Correct the last index (due to number rounding issues) -----------
_dest[i] = std::complex<float>(1.0 - 2.0 * _code[_codeLength - 1], 0);
}
else
{
_dest[i] = std::complex<float>(1.0 - 2.0 * _code[_codeValueIndex], 0); //repeat the chip -> upsample
}
}
delete[] _code;
}
void gps_l5q_code_gen_complex(std::complex<float>* _dest, uint32_t _prn)
{
auto* _code = new int32_t[GPS_L5Q_CODE_LENGTH_CHIPS];
if (_prn > 0 and _prn < 51)
{
make_l5q(_code, _prn - 1);
}
for (int32_t i = 0; i < GPS_L5Q_CODE_LENGTH_CHIPS; i++)
{
_dest[i] = std::complex<float>(1.0 - 2.0 * _code[i], 0.0);
}
delete[] _code;
}
void gps_l5q_code_gen_float(float* _dest, uint32_t _prn)
{
auto* _code = new int32_t[GPS_L5Q_CODE_LENGTH_CHIPS];
if (_prn > 0 and _prn < 51)
{
make_l5q(_code, _prn - 1);
}
for (int32_t i = 0; i < GPS_L5Q_CODE_LENGTH_CHIPS; i++)
{
_dest[i] = 1.0 - 2.0 * static_cast<float>(_code[i]);
}
delete[] _code;
}
/*
* Generates complex GPS L5i code for the desired SV ID and sampled to specific sampling frequency
*/
void gps_l5q_code_gen_complex_sampled(std::complex<float>* _dest, uint32_t _prn, int32_t _fs)
{
auto* _code = new int32_t[GPS_L5Q_CODE_LENGTH_CHIPS];
if (_prn > 0 and _prn < 51)
{
make_l5q(_code, _prn - 1);
}
int32_t _samplesPerCode, _codeValueIndex;
float _ts;
float _tc;
const int32_t _codeLength = GPS_L5Q_CODE_LENGTH_CHIPS;
//--- Find number of samples per spreading code ----------------------------
_samplesPerCode = static_cast<int32_t>(static_cast<double>(_fs) / (static_cast<double>(GPS_L5Q_CODE_RATE_HZ) / static_cast<double>(_codeLength)));
//--- Find time constants --------------------------------------------------
_ts = 1.0 / static_cast<float>(_fs); // Sampling period in sec
_tc = 1.0 / static_cast<float>(GPS_L5Q_CODE_RATE_HZ); // C/A chip period in sec
//float aux;
for (int32_t i = 0; i < _samplesPerCode; i++)
{
//=== Digitizing =======================================================
//--- Make index array to read L5 code values -------------------------
//TODO: Check this formula! Seems to start with an extra sample
_codeValueIndex = std::ceil((_ts * (static_cast<float>(i) + 1)) / _tc) - 1;
//aux = (_ts * (i + 1)) / _tc;
//_codeValueIndex = static_cast<int32_t> (static_cast<long>(aux)) - 1;
//--- Make the digitized version of the L2C code -----------------------
if (i == _samplesPerCode - 1)
{
//--- Correct the last index (due to number rounding issues) -----------
_dest[i] = std::complex<float>(1.0 - 2.0 * _code[_codeLength - 1], 0);
}
else
{
_dest[i] = std::complex<float>(1.0 - 2.0 * _code[_codeValueIndex], 0); //repeat the chip -> upsample
}
}
delete[] _code;
}
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