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GLONASS L2 CA Signal Addition

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Adds GLONASS L2 C/A signal processing to GNSS-SDR based on previous
work developed for the L1 signal. All code have been added in a single
commit with the idea to illustrate the process of signal addition for
future work
This commit is contained in:
Damian Miralles
2018-03-24 12:42:04 -06:00
parent 30d1494eec
commit 287d38dea2
55 changed files with 6959 additions and 74 deletions
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1
src/algorithms/libs/CMakeLists.txt
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@@ -27,6 +27,7 @@ set(GNSS_SPLIBS_SOURCES
gnss_signal_processing.cc
gps_sdr_signal_processing.cc
glonass_l1_signal_processing.cc
glonass_l2_signal_processing.cc
pass_through.cc
galileo_e5_signal_processing.cc
complex_byte_to_float_x2.cc

152
src/algorithms/libs/glonass_l2_signal_processing.cc Normal file
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@@ -0,0 +1,152 @@
/*!
* \file glonass_l2_signal_processing.cc
* \brief This class implements various functions for GLONASS L2 CA signals
* \author Damian Miralles, 2018, dmiralles2009(at)gmail.com
*
* Detailed description of the file here if needed.
*
* -------------------------------------------------------------------------
*
* Copyright (C) 2010-2015 (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 <http://www.gnu.org/licenses/>.
*
* -------------------------------------------------------------------------
*/
#include "glonass_l2_signal_processing.h"
auto auxCeil = [](float x) { return static_cast<int>(static_cast<long>((x) + 1)); };
void glonass_l2_ca_code_gen_complex(std::complex<float>* _dest, /* signed int _prn,*/ unsigned int _chip_shift)
{
const unsigned int _code_length = 511;
bool G1[_code_length];
bool G1_register[9];
bool feedback1;
bool aux;
unsigned int delay;
unsigned int lcv, lcv2;
for (lcv = 0; lcv < 9; lcv++)
{
G1_register[lcv] = 1;
}
/* Generate G1 Register */
for (lcv = 0; lcv < _code_length; lcv++)
{
G1[lcv] = G1_register[2];
feedback1 = G1_register[4] ^ G1_register[0];
for (lcv2 = 0; lcv2 < 8; lcv2++)
{
G1_register[lcv2] = G1_register[lcv2 + 1];
}
G1_register[8] = feedback1;
}
/* Generate PRN from G1 Register */
for (lcv = 0; lcv < _code_length; lcv++)
{
aux = G1[lcv];
if (aux == true)
{
_dest[lcv] = std::complex<float>(1, 0);
}
else
{
_dest[lcv] = std::complex<float>(-1, 0);
}
}
/* Set the delay */
delay = _code_length;
delay += _chip_shift;
delay %= _code_length;
/* Generate PRN from G1 and G2 Registers */
for (lcv = 0; lcv < _code_length; lcv++)
{
aux = G1[(lcv + _chip_shift) % _code_length];
if (aux == true)
{
_dest[lcv] = std::complex<float>(1, 0);
}
else
{
_dest[lcv] = std::complex<float>(-1, 0);
}
delay++;
delay %= _code_length;
}
}
/*
* Generates complex GLONASS L2 C/A code for the desired SV ID and sampled to specific sampling frequency
*/
void glonass_l2_ca_code_gen_complex_sampled(std::complex<float>* _dest, /* unsigned int _prn,*/ signed int _fs, unsigned int _chip_shift)
{
// This function is based on the GNU software GPS for MATLAB in the Kay Borre book
std::complex<float> _code[511];
signed int _samplesPerCode, _codeValueIndex;
float _ts;
float _tc;
float aux;
const signed int _codeFreqBasis = 511000; //Hz
const signed int _codeLength = 511;
//--- Find number of samples per spreading code ----------------------------
_samplesPerCode = static_cast<signed int>(static_cast<double>(_fs) / static_cast<double>(_codeFreqBasis / _codeLength));
//--- Find time constants --------------------------------------------------
_ts = 1.0 / static_cast<float>(_fs); // Sampling period in sec
_tc = 1.0 / static_cast<float>(_codeFreqBasis); // C/A chip period in sec
glonass_l2_ca_code_gen_complex(_code, _chip_shift); //generate C/A code 1 sample per chip
for (signed int i = 0; i < _samplesPerCode; i++)
{
//=== Digitizing =======================================================
//--- Make index array to read C/A code values -------------------------
// The length of the index array depends on the sampling frequency -
// number of samples per millisecond (because one C/A code period is one
// millisecond).
// _codeValueIndex = ceil((_ts * ((float)i + 1)) / _tc) - 1;
aux = (_ts * (i + 1)) / _tc;
_codeValueIndex = auxCeil(aux) - 1;
//--- Make the digitized version of the C/A code -----------------------
// The "upsampled" code is made by selecting values form the CA code
// chip array (caCode) for the time instances of each sample.
if (i == _samplesPerCode - 1)
{
//--- Correct the last index (due to number rounding issues) -----------
_dest[i] = _code[_codeLength - 1];
}
else
{
_dest[i] = _code[_codeValueIndex]; //repeat the chip -> upsample
}
}
}

47
src/algorithms/libs/glonass_l2_signal_processing.h Normal file
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@@ -0,0 +1,47 @@
/*!
* \file glonass_l2_signal_processing.h
* \brief This class implements various functions for GLONASS L2 CA signals
* \author Damian Miralles, 2018, dmiralles2009(at)gmail.com
*
* Detailed description of the file here if needed.
*
* -------------------------------------------------------------------------
*
* Copyright (C) 2010-2017 (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 <http://www.gnu.org/licenses/>.
*
* -------------------------------------------------------------------------
*/
#ifndef GNSS_SDR_GLONASS_L2_SIGNAL_PROCESSING_H_
#define GNSS_SDR_GLONASS_L2_SIGNAL_PROCESSING_H_
#include <complex>
//!Generates complex GLONASS L2 C/A code for the desired SV ID and code shift, and sampled to specific sampling frequency
void glonass_l2_ca_code_gen_complex(std::complex<float>* _dest, /*signed int _prn,*/ unsigned int _chip_shift);
//! Generates N complex GLONASS L2 C/A codes for the desired SV ID and code shift
void glonass_l2_ca_code_gen_complex_sampled(std::complex<float>* _dest, /* unsigned int _prn,*/ signed int _fs, unsigned int _chip_shift, unsigned int _ncodes);
//! Generates complex GLONASS L2 C/A code for the desired SV ID and code shift
void glonass_l2_ca_code_gen_complex_sampled(std::complex<float>* _dest, /* unsigned int _prn,*/ signed int _fs, unsigned int _chip_shift);
#endif /* GNSS_SDR_GLONASS_L2_SIGNAL_PROCESSING_H_ */