mirror of https://github.com/gnss-sdr/gnss-sdr
245 lines
9.3 KiB
C
245 lines
9.3 KiB
C
/*!
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* \file GPS_L1_CA.h
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* \brief Defines system parameters for GPS L1 C/A signal
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* \author Javier Arribas, 2011. jarribas(at)cttc.es
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*
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* -------------------------------------------------------------------------
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*
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* Copyright (C) 2010-2011 (see AUTHORS file for a list of contributors)
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*
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* GNSS-SDR is a software defined Global Navigation
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* Satellite Systems receiver
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*
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* This file is part of GNSS-SDR.
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*
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* GNSS-SDR is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* at your option) any later version.
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*
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* GNSS-SDR is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with GNSS-SDR. If not, see <http://www.gnu.org/licenses/>.
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*
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* -------------------------------------------------------------------------
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*/
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#ifndef GPS_DEFINES_H
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#define GPS_DEFINES_H
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#define NAVIGATION_SOLUTION_RATE_MS 1000
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// GPS CONSTANTS
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// JAVI: ADD SYSTEM PREFIX
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// SEPARATE FILE GPS.H
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const float GPS_C_m_s= 299792458.0; // The speed of light, [m/s]
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const float GPS_C_m_ms= 299792.4580; // The speed of light, [m/ms]
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const float GPS_STARTOFFSET_ms= 68.802; //[ms] Initial sign. travel time
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const double GPS_PI = 3.1415926535898; // Pi used in the GPS coordinate system
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// carrier and code frequencies
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const float GPS_L1_FREQ_HZ = 1.57542e9;
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const float GPS_L2_FREQ_HZ = 1.22760e9;
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const float GPS_L1_CA_CODE_RATE_HZ = 1.023e6;
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const float GPS_L1_CA_CODE_LENGTH_CHIPS = 1023.0;
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//-- Constants for satellite position calculation -------------------------
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const double OMEGA_EARTH_DOT = 7.2921151467e-5; // Earth rotation rate, [rad/s]
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const double GM = 3.986005e14; // Universal gravitational constant times the mass of the Earth, [m^3/s^2]
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const double F = -4.442807633e-10; // Constant, [sec/(meter)^(1/2)]
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// NAVIGATION MESSAGE DEMODULATION AND DECODING
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#define GPS_PREAMBLE {1, 0, 0, 0, 1, 0, 1, 1}
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#define GPS_CA_PREAMBLE_LENGTH_BITS 8
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#define GPS_CA_TELEMETRY_RATE_BITS_SECOND 50
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#define GPS_WORD_LENGTH 4 // CRC + GPS WORD (-2 -1 0 ... 29) Bits = 4 bytes
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#define GPS_SUBFRAME_LENGTH 40 // GPS_WORD_LENGTH x 10 = 40 bytes
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#define GPS_SUBFRAME_BITS 300
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#define GPS_WORD_BITS 30
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/*!
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* Maximum Time-Of-Arrival (TOA) difference between satellites for a receiveer operated on Earth surface is 20 ms, according to the GPS orbit model descrived in [1] Pag. 32.
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* It should be taken into account to set the buffer size for the PRN start timestamp in the pseudorranges block.
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*
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* [1] J. Bao-Yen Tsui, Fundamentals of Global Positioning System Receivers. A Software Approach, John Wiley & Sons, Inc., Hoboken, NJ, 2n edition, 2005.
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*/
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#define MAX_TOA_DELAY_MS 20
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#define num_of_slices(x) sizeof(x)/sizeof(bits_slice)
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/*! @ingroup GPS_DEFINES
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* @brief Navigation message bits slice structure: A portion of bits is indicated by
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* the start position inside the subframe and the length in number of bits */
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typedef struct bits_slice{
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int position;
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int length;
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bits_slice(int p,int l)
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{
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position=p;
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length=l;
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}
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} bits_slice;
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/*! @ingroup GPS_DEFINES
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* @brief Demodulator gnss_synchro structure, used to feed the pseudorange block */
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typedef struct gnss_synchro
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{
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double preamble_delay_ms;
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double prn_delay_ms;
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double preamble_code_phase_ms;
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double preamble_code_phase_correction_ms;
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int satellite_PRN;
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int channel_ID;
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bool valid_word;
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bool flag_preamble;
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} gnss_synchro;
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/*! @ingroup GPS_DEFINES
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* @brief Observables structure, used to feed the PVT block */
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typedef struct gnss_pseudorange
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{
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double pseudorange_m;
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double timestamp_ms;
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int SV_ID;
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bool valid;
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} gnss_pseudorange;
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/* Constants for scaling the ephemeris found in the data message
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the format is the following: TWO_N5 -> 2^-5, TWO_P4 -> 2^4, PI_TWO_N43 -> Pi*2^-43, etc etc
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Additionally some of the PI*2^N terms are used in the tracking stuff
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TWO_PX ==> 2^X
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TWO_NX ==> 2^-X
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PI_TWO_NX ==> Pi*2^-X
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PI_TWO_PX ==> Pi*2^X
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ONE_PI_TWO_PX = (1/Pi)*2^X
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*/
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// SEPARATE FILE: CONSTANTS.H
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#define TWO_P4 (16) //!< 2^4
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#define TWO_P11 (2048) //!< 2^11
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#define TWO_P12 (4096) //!< 2^12
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#define TWO_P14 (16384) //!< 2^14
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#define TWO_P16 (65536) //!< 2^16
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#define TWO_P19 (524288) //!< 2^19
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#define TWO_P31 (2147483648.0) //!< 2^31
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#define TWO_P32 (4294967296.0) //!< 2^32 this is too big for an int so add the x.0
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#define TWO_P57 (1.441151880758559e+017) //!< 2^57
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#define TWO_N5 (0.03125) //!< 2^-5
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#define TWO_N11 (4.882812500000000e-004) //!< 2^-11
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#define TWO_N19 (1.907348632812500e-006) //!< 2^-19
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#define TWO_N20 (9.536743164062500e-007) //!< 2^-20
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#define TWO_N21 (4.768371582031250e-007) //!< 2^-21
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#define TWO_N24 (5.960464477539063e-008) //!< 2^-24
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#define TWO_N25 (2.980232238769531e-008) //!< 2^-25
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#define TWO_N27 (7.450580596923828e-009) //!< 2^-27
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#define TWO_N29 (1.862645149230957e-009) //!< 2^-29
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#define TWO_N30 (9.313225746154785e-010) //!< 2^-30
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#define TWO_N31 (4.656612873077393e-010) //!< 2^-31
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#define TWO_N32 (2.328306436538696e-010) //!< 2^-32
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#define TWO_N33 (1.164153218269348e-010) //!< 2^-33
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#define TWO_N38 (3.637978807091713e-012) //!< 2^-38
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#define TWO_N43 (1.136868377216160e-013) //!< 2^-43
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#define TWO_N50 (8.881784197001252e-016) //!< 2^-50
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#define TWO_N55 (2.775557561562891e-017) //!< 2^-55
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#define TWO_P56 (7.205759403792794e+016) //!< 2^56
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#define TWO_P57 (1.441151880758559e+017) //!< 2^57
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#define PI_TWO_N19 (5.992112452678286e-006) //!< Pi*2^-19
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#define PI_TWO_N43 (3.571577341960839e-013) //!< Pi*2^-43
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#define PI_TWO_N31 (1.462918079267160e-009) //!< Pi*2^-31
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#define PI_TWO_N38 (1.142904749427469e-011) //!< Pi*2^-38
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#define PI_TWO_N23 (3.745070282923929e-007) //!< Pi*2^-23
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// GPS NAVIGATION MESSAGE STRUCTURE
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// NAVIGATION MESSAGE FIELDS POSITIONS (from GPS SPS Signal specifications)
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// SUBFRAME 1-5 (TLM and HOW)
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const bits_slice SUBFRAME_ID[]= {{50,3}};
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const bits_slice TOW[]= {{31,17}};
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// SUBFRAME 1
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const bits_slice GPS_WEEK[]= {{61,10}};
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const bits_slice SV_ACCURACY[]= {{73,4}};
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const bits_slice SV_HEALTH[]= {{77,6}};
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const bits_slice T_GD[]= {{197,8}};
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const double T_GD_LSB=TWO_N31;
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const bits_slice IODC[]= {{83,2},{211,8}};
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const bits_slice T_OC[]= {{219,16}};
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const double T_OC_LSB=TWO_P4;
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const bits_slice A_F2[]= {{241,8}};
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const double A_F2_LSB=TWO_N55;
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const bits_slice A_F1[]= {{249,16}};
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const double A_F1_LSB=TWO_N43;
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const bits_slice A_F0[]= {{271,22}};
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const double A_F0_LSB=TWO_N31;
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// SUBFRAME 2
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const bits_slice IODE_SF2[]= {{61,8}};
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const bits_slice C_RS[]= {{69,16}};
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const double C_RS_LSB=TWO_N5;
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const bits_slice DELTA_N[]= {{91,16}};
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const double DELTA_N_LSB=PI_TWO_N43;
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const bits_slice M_0[]= {{107,8},{121,24}};
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const double M_0_LSB=PI_TWO_N31;
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const bits_slice C_UC[]= {{151,16}};
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const double C_UC_LSB=TWO_N29;
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const bits_slice E[]= {{167,8},{181,24}};
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const double E_LSB=TWO_N33;
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const bits_slice C_US[]= {{211,16}};
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const double C_US_LSB=TWO_N29;
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const bits_slice SQRT_A[]= {{227,8},{241,24}};
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const double SQRT_A_LSB=TWO_N19;
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const bits_slice T_OE[]= {{271,16}};
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const double T_OE_LSB=TWO_P4;
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// SUBFRAME 3
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const bits_slice C_IC[]= {{61,16}};
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const double C_IC_LSB=TWO_N29;
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const bits_slice OMEGA_0[]= {{77,8},{91,24}};
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const double OMEGA_0_LSB=PI_TWO_N31;
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const bits_slice C_IS[]= {{121,16}};
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const double C_IS_LSB=TWO_N29;
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const bits_slice I_0[]= {{137,8},{151,24}};
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const double I_0_LSB=PI_TWO_N31;
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const bits_slice C_RC[]= {{181,16}};
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const double C_RC_LSB=TWO_N5;
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const bits_slice OMEGA[]= {{197,8},{211,24}};
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const double OMEGA_LSB=PI_TWO_N31;
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const bits_slice OMEGA_DOT[]= {{241,24}};
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const double OMEGA_DOT_LSB=PI_TWO_N43;
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const bits_slice IODE_SF3[]= {{271,8}};
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const bits_slice I_DOT[]= {{279,14}};
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const double I_DOT_LSB=PI_TWO_N43;
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// SUBFRAME 4-5
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const bits_slice SV_DATA_ID[]= {{61,2}};
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const bits_slice SV_PAGE[]= {{63,6}};
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// SUBFRAME 4
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// SUBFRAME 5
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#endif /* GPS_DEFINES_H */
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