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gnss-sdr/src/algorithms/libs/beidou_b3i_signal_processing.cc
Carles Fernandez f821caea4a
Code cleaning
2019-06-29 22:47:21 +02:00

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/*!
* \file beidou_b3i_signal_processing.cc
* \brief This class implements various functions for BeiDou B1I signal
* \author Damian Miralles, 2019. dmiralles2009@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 "beidou_b3i_signal_processing.h"
auto auxCeil = [](float x) { return static_cast<int>(static_cast<long>((x) + 1)); };
void beidou_b3i_code_gen_int(gsl::span<int> _dest, signed int _prn, unsigned int _chip_shift)
{
const unsigned int _code_length = 10230;
bool G1[_code_length];
bool G2[_code_length];
std::array<bool, 13> G1_register = {{true, true, true, true, true, true, true, true, true, true, true, true, true}};
std::array<bool, 13> G2_register = {{true, true, true, true, true, true, true, true, true, true, true, true, true}};
std::array<bool, 13> G1_register_reset = {{false, false, true, true, true, true, true, true, true, true, true, true, true}};
bool feedback1, feedback2, aux;
uint32_t lcv, lcv2, delay;
int32_t prn_idx = _prn - 1;
std::array<std::array<bool, 13>, 63> G2_register_shifted =
{{{{true, false, true, false, true, true, true, true, true, true, true, true, true}},
{{true, true, true, true, false, false, false, true, false, true, false, true, true}},
{{true, false, true, true, true, true, false, false, false, true, false, true, false}},
{{true, true, true, true, true, true, true, true, true, true, false, true, true}},
{{true, true, false, false, true, false, false, false, true, true, true, true, true}},
{{true, false, false, true, false, false, true, true, false, false, true, false, false}},
{{true, true, true, true, true, true, true, false, true, false, false, true, false}},
{{true, true, true, false, true, true, true, true, true, true, true, false, true}},
{{true, false, true, false, false, false, false, false, false, false, false, true, false}},
{{false, false, true, false, false, false, false, false, true, true, false, true, true}},
{{true, true, true, false, true, false, true, true, true, false, false, false, false}},
{{false, false, true, false, true, true, false, false, true, true, true, true, false}},
{{false, true, true, false, false, true, false, false, true, false, true, false, true}},
{{false, true, true, true, false, false, false, true, false, false, true, true, false}},
{{true, false, false, false, true, true, false, false, false, true, false, false, true}},
{{true, true, true, false, false, false, true, true, true, true, true, false, false}},
{{false, false, true, false, false, true, true, false, false, false, true, false, true}},
{{false, false, false, false, false, true, true, true, false, true, true, false, false}},
{{true, false, false, false, true, false, true, false, true, false, true, true, true}},
{{false, false, false, true, false, true, true, false, true, true, true, true, false}},
{{false, false, true, false, false, false, false, true, false, true, true, false, true}},
{{false, false, true, false, true, true, false, false, false, true, false, true, false}},
{{false, false, false, true, false, true, true, false, false, true, true, true, true}},
{{false, false, true, true, false, false, true, true, false, false, false, true, false}},
{{false, false, true, true, true, false, true, false, false, true, false, false, false}},
{{false, true, false, false, true, false, false, true, false, true, false, false, true}},
{{true, false, true, true, false, true, true, false, true, false, false, true, true}},
{{true, false, true, false, true, true, true, true, false, false, false, true, false}},
{{false, false, false, true, false, true, true, true, true, false, true, false, true}},
{{false, true, true, true, true, true, true, true, true, true, true, true, true}},
{{false, true, true, false, true, true, false, false, false, true, true, true, true}},
{{true, false, true, false, true, true, false, false, false, true, false, false, true}},
{{true, false, false, true, false, true, false, true, false, true, false, true, true}},
{{true, true, false, false, true, true, false, true, false, false, true, false, true}},
{{true, true, false, true, false, false, true, false, true, true, true, false, true}},
{{true, true, true, true, true, false, true, true, true, false, true, false, false}},
{{false, false, true, false, true, false, true, true, false, false, true, true, true}},
{{true, true, true, false, true, false, false, false, true, false, false, false, false}},
{{true, true, false, true, true, true, false, false, true, false, false, false, false}},
{{true, true, false, true, false, true, true, false, false, true, true, true, false}},
{{true, false, false, false, false, false, false, true, true, false, true, false, false}},
{{false, true, false, true, true, true, true, false, true, true, false, false, true}},
{{false, true, true, false, true, true, false, true, true, true, true, false, false}},
{{true, true, false, true, false, false, true, true, true, false, false, false, true}},
{{false, false, true, true, true, false, false, true, false, false, false, true, false}},
{{false, true, false, true, false, true, true, false, false, false, true, false, true}},
{{true, false, false, true, true, true, true, true, false, false, true, true, false}},
{{true, true, true, true, true, false, true, false, false, true, false, false, false}},
{{false, false, false, false, true, false, true, false, false, true, false, false, true}},
{{true, false, false, false, false, true, false, true, false, true, true, false, false}},
{{true, true, true, true, false, false, true, false, false, true, true, false, false}},
{{false, true, false, false, true, true, false, false, false, true, true, true, true}},
{{false, false, false, false, false, false, false, false, true, true, false, false, false}},
{{true, false, false, false, false, false, false, false, false, false, true, false, false}},
{{false, false, true, true, false, true, false, true, false, false, true, true, false}},
{{true, false, true, true, false, false, true, false, false, false, true, true, false}},
{{false, true, true, true, false, false, true, true, true, true, false, false, false}},
{{false, false, true, false, true, true, true, false, false, true, false, true, false}},
{{true, true, false, false, true, true, true, true, true, false, true, true, false}},
{{true, false, false, true, false, false, true, false, false, false, true, false, true}},
{{false, true, true, true, false, false, false, true, false, false, false, false, false}},
{{false, false, true, true, false, false, true, false, false, false, false, true, false}},
{{false, false, true, false, false, false, true, false, false, true, true, true, false}}}};
// A simple error check
if ((prn_idx < 0) || (prn_idx > 63))
{
return;
}
// Assign shifted G2 register based on prn number
G2_register = G2_register_shifted[prn_idx];
std::reverse(G2_register.begin(), G2_register.end());
// Generate G1 and G2 Register
for (lcv = 0; lcv < _code_length; lcv++)
{
G1[lcv] = G1_register[0];
G2[lcv] = G2_register[0];
//feedback1 = (test_G1_register[0]+test_G1_register[2]+test_G1_register[3]+test_G1_register[12]) & 0x1;
feedback1 = (G1_register[0] + G1_register[9] + G1_register[10] + G1_register[12]) & 0x01;
feedback2 = (G2_register[0] + G2_register[1] + G2_register[3] + G2_register[4] +
G2_register[6] + G2_register[7] + G2_register[8] + G2_register[12]) &
0x01;
for (lcv2 = 0; lcv2 < 12; lcv2++)
{
G1_register[lcv2] = G1_register[lcv2 + 1];
G2_register[lcv2] = G2_register[lcv2 + 1];
}
G1_register[12] = feedback1;
G2_register[12] = feedback2;
// Reset G1 register if sequence found
if (G1_register == G1_register_reset)
{
G1_register = {{true, true, true, true, true, true, true, true, true, true, true, true, true}};
}
}
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] + G2[delay]) & 0x01;
if (aux == true)
{
_dest[lcv] = 1;
}
else
{
_dest[lcv] = -1;
}
delay++;
delay %= _code_length;
}
}
void beidou_b3i_code_gen_float(gsl::span<float> _dest, signed int _prn, unsigned int _chip_shift)
{
unsigned int _code_length = 10230;
int b3i_code_int[10230];
beidou_b3i_code_gen_int(b3i_code_int, _prn, _chip_shift);
for (unsigned int ii = 0; ii < _code_length; ++ii)
{
_dest[ii] = static_cast<float>(b3i_code_int[ii]);
}
}
void beidou_b3i_code_gen_complex(gsl::span<std::complex<float>> _dest, signed int _prn, unsigned int _chip_shift)
{
unsigned int _code_length = 10230;
int b3i_code_int[10230];
beidou_b3i_code_gen_int(b3i_code_int, _prn, _chip_shift);
for (unsigned int ii = 0; ii < _code_length; ++ii)
{
_dest[ii] = std::complex<float>(static_cast<float>(b3i_code_int[ii]), 0.0F);
}
}
void beidou_b3i_code_gen_complex_sampled(gsl::span<std::complex<float>> _dest, unsigned int _prn, 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[10230];
signed int _samplesPerCode, _codeValueIndex;
float _ts;
float _tc;
float aux;
const signed int _codeFreqBasis = 10230000; //Hz
const signed int _codeLength = 10230;
//--- 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
beidou_b3i_code_gen_complex(_code, _prn, _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
}
}
}
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