/*!
* \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 .
*
* -------------------------------------------------------------------------
*/
#include "gps_l5_signal.h"
#include "GPS_L5.h"
#include
std::deque l5i_xa_shift(std::deque xa) // GPS-IS-705E Figure 3-4 pp. 15
{
if (xa == std::deque{true, true, true, true, true, true, true, true, true, true, true, false, true})
{
return std::deque{true, true, true, true, true, true, true, true, true, true, true, true, true};
}
std::deque out(xa.begin(), xa.end() - 1);
out.push_front(xa[12] xor xa[11] xor xa[9] xor xa[8]);
return out;
}
std::deque l5q_xa_shift(std::deque xa)
{
if (xa == std::deque{true, true, true, true, true, true, true, true, true, true, true, false, true})
{
return std::deque{true, true, true, true, true, true, true, true, true, true, true, true, true};
}
std::deque out(xa.begin(), xa.end() - 1);
out.push_front(xa[12] xor xa[11] xor xa[9] xor xa[8]);
return out;
}
std::deque l5i_xb_shift(std::deque xb) // GPS-IS-705E Figure 3-5 pp. 16
{
std::deque 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 l5q_xb_shift(std::deque xb)
{
std::deque 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 make_l5i_xa()
{
std::deque xa = {true, true, true, true, true, true, true, true, true, true, true, true, true};
std::deque 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 make_l5i_xb()
{
std::deque xb = {true, true, true, true, true, true, true, true, true, true, true, true, true};
std::deque 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 make_l5q_xa()
{
std::deque xa = {true, true, true, true, true, true, true, true, true, true, true, true, true};
std::deque 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 make_l5q_xb()
{
std::deque xb = {true, true, true, true, true, true, true, true, true, true, true, true, true};
std::deque 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(gsl::span _dest, int32_t prn)
{
int32_t xb_offset = GPS_L5I_INIT_REG[prn];
std::deque xb = make_l5i_xb();
std::deque xa = make_l5i_xa();
std::deque 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];
}
for (int32_t n = 0; n < GPS_L5I_CODE_LENGTH_CHIPS; n++)
{
_dest[n] = xa[n] xor xb_shift[n];
}
}
void make_l5q(gsl::span _dest, int32_t prn)
{
int32_t xb_offset = GPS_L5Q_INIT_REG[prn];
std::deque xb = make_l5q_xb();
std::deque xa = make_l5q_xa();
std::deque 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];
}
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(gsl::span> _dest, uint32_t _prn)
{
std::unique_ptr _code{new int32_t[GPS_L5I_CODE_LENGTH_CHIPS]};
gsl::span _code_span(_code, GPS_L5I_CODE_LENGTH_CHIPS);
if (_prn > 0 and _prn < 51)
{
make_l5i(_code_span, _prn - 1);
}
for (int32_t i = 0; i < GPS_L5I_CODE_LENGTH_CHIPS; i++)
{
_dest[i] = std::complex(1.0 - 2.0 * _code_span[i], 0.0);
}
}
void gps_l5i_code_gen_float(gsl::span _dest, uint32_t _prn)
{
std::unique_ptr _code{new int32_t[GPS_L5I_CODE_LENGTH_CHIPS]};
gsl::span _code_span(_code, GPS_L5I_CODE_LENGTH_CHIPS);
if (_prn > 0 and _prn < 51)
{
make_l5i(_code_span, _prn - 1);
}
for (int32_t i = 0; i < GPS_L5I_CODE_LENGTH_CHIPS; i++)
{
_dest[i] = 1.0 - 2.0 * static_cast(_code_span[i]);
}
}
/*
* Generates complex GPS L5i code for the desired SV ID and sampled to specific sampling frequency
*/
void gps_l5i_code_gen_complex_sampled(gsl::span> _dest, uint32_t _prn, int32_t _fs)
{
std::unique_ptr _code{new int32_t[GPS_L5I_CODE_LENGTH_CHIPS]};
gsl::span _code_span(_code, GPS_L5I_CODE_LENGTH_CHIPS);
if (_prn > 0 and _prn < 51)
{
make_l5i(_code_span, _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(static_cast(_fs) / (static_cast(GPS_L5I_CODE_RATE_HZ) / static_cast(_codeLength)));
//--- Find time constants --------------------------------------------------
_ts = 1.0 / static_cast(_fs); // Sampling period in sec
_tc = 1.0 / static_cast(GPS_L5I_CODE_RATE_HZ); // L5I primary chip period in sec
for (int32_t i = 0; i < _samplesPerCode; i++)
{
//=== Digitizing =======================================================
//--- Make index array to read L5 code values -------------------------
_codeValueIndex = static_cast(std::ceil(_ts * static_cast(i + 1) / _tc)) - 1;
//--- Make the digitized version of the L5I code -----------------------
if (i == _samplesPerCode - 1)
{
//--- Correct the last index (due to number rounding issues) -----------
_dest[i] = std::complex(1.0 - 2.0 * _code_span[_codeLength - 1], 0.0);
}
else
{
_dest[i] = std::complex(1.0 - 2.0 * _code_span[_codeValueIndex], 0.0); // repeat the chip -> upsample
}
}
}
void gps_l5q_code_gen_complex(gsl::span> _dest, uint32_t _prn)
{
std::unique_ptr _code{new int32_t[GPS_L5Q_CODE_LENGTH_CHIPS]};
gsl::span _code_span(_code, GPS_L5Q_CODE_LENGTH_CHIPS);
if (_prn > 0 and _prn < 51)
{
make_l5q(_code_span, _prn - 1);
}
for (int32_t i = 0; i < GPS_L5Q_CODE_LENGTH_CHIPS; i++)
{
_dest[i] = std::complex(1.0 - 2.0 * _code_span[i], 0.0);
}
}
void gps_l5q_code_gen_float(gsl::span _dest, uint32_t _prn)
{
std::unique_ptr _code{new int32_t[GPS_L5Q_CODE_LENGTH_CHIPS]};
gsl::span _code_span(_code, GPS_L5Q_CODE_LENGTH_CHIPS);
if (_prn > 0 and _prn < 51)
{
make_l5q(_code_span, _prn - 1);
}
for (int32_t i = 0; i < GPS_L5Q_CODE_LENGTH_CHIPS; i++)
{
_dest[i] = 1.0 - 2.0 * static_cast(_code_span[i]);
}
}
/*
* Generates complex GPS L5Q code for the desired SV ID and sampled to specific sampling frequency
*/
void gps_l5q_code_gen_complex_sampled(gsl::span> _dest, uint32_t _prn, int32_t _fs)
{
std::unique_ptr _code{new int32_t[GPS_L5Q_CODE_LENGTH_CHIPS]};
gsl::span _code_span(_code, GPS_L5Q_CODE_LENGTH_CHIPS);
if (_prn > 0 and _prn < 51)
{
make_l5q(_code_span, _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(static_cast(_fs) / (static_cast(GPS_L5Q_CODE_RATE_HZ) / static_cast(_codeLength)));
//--- Find time constants --------------------------------------------------
_ts = 1.0 / static_cast(_fs); // Sampling period in sec
_tc = 1.0 / static_cast(GPS_L5Q_CODE_RATE_HZ); // L5Q chip period in sec
//float aux;
for (int32_t i = 0; i < _samplesPerCode; i++)
{
//=== Digitizing =======================================================
//--- Make index array to read L5 code values -------------------------
_codeValueIndex = static_cast(std::ceil(_ts * static_cast(i + 1) / _tc)) - 1;
//--- Make the digitized version of the L5Q code -----------------------
if (i == _samplesPerCode - 1)
{
//--- Correct the last index (due to number rounding issues) -----------
_dest[i] = std::complex(1.0 - 2.0 * _code_span[_codeLength - 1], 0);
}
else
{
_dest[i] = std::complex(1.0 - 2.0 * _code_span[_codeValueIndex], 0); // repeat the chip -> upsample
}
}
}