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Definition in file gps.c.
#include <math.h>
#include "gnss_error.h"
#include "gps.h"
#include "constants.h"
#include "geodesy.h"
Go to the source code of this file.
Defines | |
#define | GPS_CLOCK_CORRECTION_RELATIVISTIC_CONSTANT_F (-4.442807633e-10) |
combined constant defined in ICD-GPS-200C p. 88 [s]/[sqrt(m)] | |
#define | GPS_UNIVERSAL_GRAVITY_CONSTANT (3.986005e14) |
gravity constant defined on ICD-GPS-200C p. 98 [m^3/s^2] | |
#define | GPS_RATIO_OF_SQUARED_FREQUENCIES_L1_OVER_L2 (1.6469444444444444444444444444444) |
(f_L1/f_L2)^2 = (1575.42/1227.6)^2 = (77/60)^2 | |
#define | GPS_WGS84_EARTH_ROTATION_RATE (7.2921151467e-05) |
constant defined on ICD-GPS-200C p. 98 [rad/s] | |
Functions | |
void | GPS_ComputeSatelliteClockCorrectionAndDrift (const unsigned short transmission_gpsweek, const double transmission_gpstow, const unsigned short ephem_week, const unsigned toe, const unsigned toc, const double af0, const double af1, const double af2, const double ecc, const double sqrta, const double delta_n, const double m0, const double tgd, const unsigned char mode, double *clock_correction, double *clock_drift) |
void | GPS_ComputeSatellitePositionAndVelocity (const unsigned short transmission_gpsweek, const double transmission_gpstow, const unsigned short ephem_week, const unsigned toe, const double m0, const double delta_n, const double ecc, const double sqrta, const double omega0, const double i0, const double w, const double omegadot, const double idot, const double cuc, const double cus, const double crc, const double crs, const double cic, const double cis, const double estimateOfTrueRange, const double estimteOfRangeRate, double *x, double *y, double *z, double *vx, double *vy, double *vz) |
void | GPS_ComputeUserToSatelliteRange (const double userX, const double userY, const double userZ, const double satX, const double satY, const double satZ, double *range) |
void | GPS_ComputeUserToSatelliteRangeAndRangeRate (const double userX, const double userY, const double userZ, const double userVx, const double userVy, const double userVz, const double satX, const double satY, const double satZ, const double satVx, const double satVy, const double satVz, double *range, double *range_rate) |
void | GPS_ComputeSatellitePositionVelocityAzimuthElevationDoppler_BasedOnAlmanacData (const double userX, const double userY, const double userZ, const unsigned short gpsweek, const double gpstow, const double toa, const unsigned short almanac_week, const unsigned short prn, const double ecc, const double i0, const double omegadot, const double sqrta, const double omega0, const double w, const double m0, const double af0, const double af1, double *clock_correction, double *clock_drift, double *satX, double *satY, double *satZ, double *satVx, double *satVy, double *satVz, double *azimuth, double *elevation, double *doppler) |
void | GPS_ComputeSatellitePositionVelocityAzimuthElevationDoppler_BasedOnEphmerisData (const double userX, const double userY, const double userZ, const unsigned short gpsweek, const double gpstow, const unsigned short ephem_week, const unsigned toe, const unsigned toc, const double af0, const double af1, const double af2, const double tgd, const double m0, const double delta_n, const double ecc, const double sqrta, const double omega0, const double i0, const double w, const double omegadot, const double idot, const double cuc, const double cus, const double crc, const double crs, const double cic, const double cis, double *clock_correction, double *clock_drift, double *satX, double *satY, double *satZ, double *satVx, double *satVy, double *satVz, double *azimuth, double *elevation, double *doppler) |
BOOL | GPS_DecodeRawGPSEphemeris (const unsigned char subframe1[30], const unsigned char subframe2[30], const unsigned char subframe3[30], unsigned short prn, unsigned *tow, unsigned short *iodc, unsigned char *iode, unsigned *toe, unsigned *toc, unsigned short *week, unsigned char *health, unsigned char *alert_flag, unsigned char *anti_spoof, unsigned char *code_on_L2, unsigned char *ura, unsigned char *L2_P_data_flag, unsigned char *fit_interval_flag, unsigned short *age_of_data_offset, double *tgd, double *af2, double *af1, double *af0, double *m0, double *delta_n, double *ecc, double *sqrta, double *omega0, double *i0, double *w, double *omegadot, double *idot, double *cuc, double *cus, double *crc, double *crs, double *cic, double *cis) |
#define GPS_CLOCK_CORRECTION_RELATIVISTIC_CONSTANT_F (-4.442807633e-10) |
#define GPS_RATIO_OF_SQUARED_FREQUENCIES_L1_OVER_L2 (1.6469444444444444444444444444444) |
#define GPS_UNIVERSAL_GRAVITY_CONSTANT (3.986005e14) |
#define GPS_WGS84_EARTH_ROTATION_RATE (7.2921151467e-05) |
void GPS_ComputeSatelliteClockCorrectionAndDrift | ( | const unsigned short | transmission_gpsweek, | |
const double | transmission_gpstow, | |||
const unsigned short | ephem_week, | |||
const unsigned | toe, | |||
const unsigned | toc, | |||
const double | af0, | |||
const double | af1, | |||
const double | af2, | |||
const double | ecc, | |||
const double | sqrta, | |||
const double | delta_n, | |||
const double | m0, | |||
const double | tgd, | |||
const unsigned char | mode, | |||
double * | clock_correction, | |||
double * | clock_drift | |||
) |
Computes the satellite clock and clock dirft corrections given the clock model and ephemeris information.
transmission_gpsweek | GPS week when signal was transmit (0-1024+) [weeks] |
transmission_gpstow | GPS time of week when signal was transmit [s] |
ephem_week | ephemeris: GPS week (0-1024+) [weeks] |
toe | ephemeris: time of week [s] |
toc | ephemeris: clock reference time of week [s] |
af0 | ephemeris: polynomial clock correction coefficient [s], Note: parameters from ephemeris preferred vs almanac (22 vs 11 bits) |
af1 | ephemeris: polynomial clock correction coefficient [s/s], Note: parameters from ephemeris preferred vs almanac (16 vs 11 bits) |
af2 | ephemeris: polynomial clock correction coefficient [s/s^2] |
ecc | ephemeris: eccentricity of satellite orbit [] |
sqrta | ephemeris: square root of the semi-major axis of orbit [m^(1/2)] |
delta_n | ephemeris: mean motion difference from computed value [rad] |
m0 | ephemeris: mean anomaly at reference time [rad] |
tgd | ephemeris: group delay differential between L1 and L2 [s] |
mode | 0=L1 only, 1=L2 only (see p. 90, ICD-GPS-200C) |
clock_correction | satellite clock correction [m] |
clock_drift | satellite clock drift correction [m/s] |
void GPS_ComputeSatellitePositionAndVelocity | ( | const unsigned short | transmission_gpsweek, | |
const double | transmission_gpstow, | |||
const unsigned short | ephem_week, | |||
const unsigned | toe, | |||
const double | m0, | |||
const double | delta_n, | |||
const double | ecc, | |||
const double | sqrta, | |||
const double | omega0, | |||
const double | i0, | |||
const double | w, | |||
const double | omegadot, | |||
const double | idot, | |||
const double | cuc, | |||
const double | cus, | |||
const double | crc, | |||
const double | crs, | |||
const double | cic, | |||
const double | cis, | |||
const double | estimateOfTrueRange, | |||
const double | estimteOfRangeRate, | |||
double * | x, | |||
double * | y, | |||
double * | z, | |||
double * | vx, | |||
double * | vy, | |||
double * | vz | |||
) |
Computes the satellite position and velocity in WGS84 based on the supplied ephemeris/almanac parameters.
transmission_gpsweek | GPS week when signal was transmit (0-1024+) [weeks] |
transmission_gpstow | GPS time of week when signal was transmit [s] |
ephem_week | ephemeris: GPS week (0-1024+) [weeks] |
toe | ephemeris: time of week [s] |
m0 | ephemeris: mean anomaly at reference time [rad] |
delta_n | ephemeris: mean motion difference from computed value [rad] |
ecc | ephemeris: eccentricity [] |
sqrta | ephemeris: square root of the semi-major axis [m^(1/2)] |
omega0 | ephemeris: longitude of ascending node of orbit plane at weekly epoch [rad] |
i0 | ephemeris: inclination angle at reference time [rad] |
w | ephemeris: argument of perigee [rad] |
omegadot | ephemeris: rate of right ascension [rad/s] |
idot | ephemeris: rate of inclination angle [rad/s] |
cuc | ephemeris: amplitude of the cosine harmonic correction term to the argument of latitude [rad] |
cus | ephemeris: amplitude of the sine harmonic correction term to the argument of latitude [rad] |
crc | ephemeris: amplitude of the cosine harmonic correction term to the orbit radius [m] |
crs | ephemeris: amplitude of the sine harmonic correction term to the orbit radius [m] |
cic | ephemeris: amplitude of the cosine harmonic correction term to the angle of inclination [rad] |
cis | ephemeris: amplitude of the sine harmonic correction term to the angle of inclination [rad] |
estimateOfTrueRange | best estimate of the signal propagation time (in m) for Sagnac effect compensation [m] |
estimteOfRangeRate | best estimate of the true signal Doppler (in m/s) for Sagnac effect compensation [m/s] |
x | satellite x [m] |
y | satellite y [m] |
z | satellite z [m] |
vx | satellite velocity x [m/s] |
vy | satellite velocity y [m/s] |
vz | satellite velocity z [m/s] |
void GPS_ComputeSatellitePositionVelocityAzimuthElevationDoppler_BasedOnAlmanacData | ( | const double | userX, | |
const double | userY, | |||
const double | userZ, | |||
const unsigned short | gpsweek, | |||
const double | gpstow, | |||
const double | toa, | |||
const unsigned short | almanac_week, | |||
const unsigned short | prn, | |||
const double | ecc, | |||
const double | i0, | |||
const double | omegadot, | |||
const double | sqrta, | |||
const double | omega0, | |||
const double | w, | |||
const double | m0, | |||
const double | af0, | |||
const double | af1, | |||
double * | clock_correction, | |||
double * | clock_drift, | |||
double * | satX, | |||
double * | satY, | |||
double * | satZ, | |||
double * | satVx, | |||
double * | satVy, | |||
double * | satVz, | |||
double * | azimuth, | |||
double * | elevation, | |||
double * | doppler | |||
) |
Computes the satellite position and velocity in WGS84 based on almanac data.
userX | user X position WGS84 ECEF [m] |
userY | user Y position WGS84 ECEF [m] |
userZ | user Z position WGS84 ECEF [m] |
gpsweek | user gps week (0-1024+) [week] |
gpstow | user time of week [s] |
toa | time of applicability [s] |
almanac_week | gps week of almanac (0-1024+) [week] |
prn | GPS prn number [] |
ecc | eccentricity [] |
i0 | orbital inclination at reference time [rad] |
omegadot | rate of right ascension [rad/s] |
sqrta | square root of the semi-major axis [m^(1/2)] |
omega0 | longitude of ascending node of orbit plane at weekly epoch [rad] |
w | argument of perigee [rad] |
m0 | mean anomaly at reference time [rad] |
af0 | polynomial clock correction coefficient (clock bias) [s], Note: parameters from ephemeris preferred vs almanac (22 vs 11 bits) |
af1 | polynomial clock correction coefficient (clock drift) [s/s], Note: parameters from ephemeris preferred vs almanac (16 vs 11 bits) |
clock_correction | clock correction for this satellite for this epoch [m] |
clock_drift | clock drift correction for this satellite for this epoch [m/s] |
satX | satellite X position WGS84 ECEF [m] |
satY | satellite Y position WGS84 ECEF [m] |
satZ | satellite Z position WGS84 ECEF [m] |
satVx | satellite X velocity WGS84 ECEF [m/s] |
satVy | satellite Y velocity WGS84 ECEF [m/s] |
satVz | satellite Z velocity WGS84 ECEF [m/s] |
azimuth | satelilte azimuth [rad] |
elevation | satelilte elevation [rad] |
doppler | satellite doppler with respect to the user position [m/s], Note: User must convert to Hz |
void GPS_ComputeSatellitePositionVelocityAzimuthElevationDoppler_BasedOnEphmerisData | ( | const double | userX, | |
const double | userY, | |||
const double | userZ, | |||
const unsigned short | gpsweek, | |||
const double | gpstow, | |||
const unsigned short | ephem_week, | |||
const unsigned | toe, | |||
const unsigned | toc, | |||
const double | af0, | |||
const double | af1, | |||
const double | af2, | |||
const double | tgd, | |||
const double | m0, | |||
const double | delta_n, | |||
const double | ecc, | |||
const double | sqrta, | |||
const double | omega0, | |||
const double | i0, | |||
const double | w, | |||
const double | omegadot, | |||
const double | idot, | |||
const double | cuc, | |||
const double | cus, | |||
const double | crc, | |||
const double | crs, | |||
const double | cic, | |||
const double | cis, | |||
double * | clock_correction, | |||
double * | clock_drift, | |||
double * | satX, | |||
double * | satY, | |||
double * | satZ, | |||
double * | satVx, | |||
double * | satVy, | |||
double * | satVz, | |||
double * | azimuth, | |||
double * | elevation, | |||
double * | doppler | |||
) |
Computes the satellite position and velocity in WGS84 based on ephemeris data.
userX | user X position WGS84 ECEF [m] |
userY | user Y position WGS84 ECEF [m] |
userZ | user Z position WGS84 ECEF [m] |
gpsweek | gps week of signal transmission (0-1024+) [week] |
gpstow | time of week of signal transmission (gpstow-psr/c) [s] |
ephem_week | ephemeris: GPS week (0-1024+) [weeks] |
toe | ephemeris: time of week [s] |
toc | ephemeris: clock reference time of week [s] |
af0 | ephemeris: polynomial clock correction coefficient [s], Note: parameters from ephemeris preferred vs almanac (22 vs 11 bits) |
af1 | ephemeris: polynomial clock correction coefficient [s/s], Note: parameters from ephemeris preferred vs almanac (16 vs 11 bits) |
af2 | ephemeris: polynomial clock correction coefficient [s/s^2] |
tgd | ephemeris: group delay differential between L1 and L2 [s] |
m0 | ephemeris: mean anomaly at reference time [rad] |
delta_n | ephemeris: mean motion difference from computed value [rad/s] |
ecc | ephemeris: eccentricity [] |
sqrta | ephemeris: square root of the semi-major axis [m^(1/2)] |
omega0 | ephemeris: longitude of ascending node of orbit plane at weekly epoch [rad] |
i0 | ephemeris: inclination angle at reference time [rad] |
w | ephemeris: argument of perigee [rad] |
omegadot | ephemeris: rate of right ascension [rad/s] |
idot | ephemeris: rate of inclination angle [rad/s] |
cuc | ephemeris: amplitude of the cosine harmonic correction term to the argument of latitude [rad] |
cus | ephemeris: amplitude of the sine harmonic correction term to the argument of latitude [rad] |
crc | ephemeris: amplitude of the cosine harmonic correction term to the orbit radius [m] |
crs | ephemeris: amplitude of the sine harmonic correction term to the orbit radius [m] |
cic | ephemeris: amplitude of the cosine harmonic correction term to the angle of inclination [rad] |
cis | ephemeris: amplitude of the sine harmonic correction term to the angle of inclination [rad] |
clock_correction | clock correction for this satellite for this epoch [m] |
clock_drift | clock drift correction for this satellite for this epoch [m/s] |
satX | satellite X position WGS84 ECEF [m] |
satY | satellite Y position WGS84 ECEF [m] |
satZ | satellite Z position WGS84 ECEF [m] |
satVx | satellite X velocity WGS84 ECEF [m/s] |
satVy | satellite Y velocity WGS84 ECEF [m/s] |
satVz | satellite Z velocity WGS84 ECEF [m/s] |
azimuth | satelilte azimuth [rad] |
elevation | satelilte elevation [rad] |
doppler | satellite doppler with respect to the user position [m/s], Note: User must convert to Hz |
void GPS_ComputeUserToSatelliteRange | ( | const double | userX, | |
const double | userY, | |||
const double | userZ, | |||
const double | satX, | |||
const double | satY, | |||
const double | satZ, | |||
double * | range | |||
) |
Computes the user to satellite range given the user and satellite position.
userX | user X position WGS84 ECEF [m] |
userY | user Y position WGS84 ECEF [m] |
userZ | user Z position WGS84 ECEF [m] |
satX | satellite X position WGS84 ECEF [m] |
satY | satellite Y positoin WGS84 ECEF [m] |
satZ | satellite Z position WGS84 ECEF [m] |
range | user to satellite range [m] |
void GPS_ComputeUserToSatelliteRangeAndRangeRate | ( | const double | userX, | |
const double | userY, | |||
const double | userZ, | |||
const double | userVx, | |||
const double | userVy, | |||
const double | userVz, | |||
const double | satX, | |||
const double | satY, | |||
const double | satZ, | |||
const double | satVx, | |||
const double | satVy, | |||
const double | satVz, | |||
double * | range, | |||
double * | range_rate | |||
) |
Computes the user to satellite range and range rate given the user and satellite position and velocities.
userX | user X position WGS84 ECEF [m] |
userY | user Y position WGS84 ECEF [m] |
userZ | user Z position WGS84 ECEF [m] |
userVx | user X velocity WGS84 ECEF [m/s] |
userVy | user Y velocity WGS84 ECEF [m/s] |
userVz | user Z velocity WGS84 ECEF [m/s] |
satX | satellite X position WGS84 ECEF [m] |
satY | satellite Y positoin WGS84 ECEF [m] |
satZ | satellite Z position WGS84 ECEF [m] |
satVx | satellite X velocity WGS84 ECEF [m/s] |
satVy | satellite Y velocity WGS84 ECEF [m/s] |
satVz | satellite Z velocity WGS84 ECEF [m/s] |
range | user to satellite range [m] |
range_rate | user to satellite range rate [m/s] |
BOOL GPS_DecodeRawGPSEphemeris | ( | const unsigned char | subframe1[30], | |
const unsigned char | subframe2[30], | |||
const unsigned char | subframe3[30], | |||
unsigned short | prn, | |||
unsigned * | tow, | |||
unsigned short * | iodc, | |||
unsigned char * | iode, | |||
unsigned * | toe, | |||
unsigned * | toc, | |||
unsigned short * | week, | |||
unsigned char * | health, | |||
unsigned char * | alert_flag, | |||
unsigned char * | anti_spoof, | |||
unsigned char * | code_on_L2, | |||
unsigned char * | ura, | |||
unsigned char * | L2_P_data_flag, | |||
unsigned char * | fit_interval_flag, | |||
unsigned short * | age_of_data_offset, | |||
double * | tgd, | |||
double * | af2, | |||
double * | af1, | |||
double * | af0, | |||
double * | m0, | |||
double * | delta_n, | |||
double * | ecc, | |||
double * | sqrta, | |||
double * | omega0, | |||
double * | i0, | |||
double * | w, | |||
double * | omegadot, | |||
double * | idot, | |||
double * | cuc, | |||
double * | cus, | |||
double * | crc, | |||
double * | crs, | |||
double * | cic, | |||
double * | cis | |||
) |
Decodes the raw gps ephemeris (note, with the parity bits removed).
code_on_L2
subframe1 | subframe 1 data, 30 bytes * 8bits/byte = 240 bits, thus parity bits have been removed |
subframe2 | subframe 2 data, 30 bytes * 8bits/byte = 240 bits, thus parity bits have been removed |
subframe3 | subframe 3 data, 30 bytes * 8bits/byte = 240 bits, thus parity bits have been removed |
prn | GPS PRN number (helps with debugging) |
tow | time of week in subframe1, the time of the leading bit edge of subframe 2 [s] |
iodc | 10 bit issue of data (clock), 8 LSB bits will match the iode [] |
iode | 8 bit issue of data (ephemeris) [] |
toe | reference time ephemeris (0-604800) [s] |
toc | reference time (clock) (0-604800) [s] |
week | 10 bit gps week 0-1023 (user must account for week rollover ) [week] |
health | 6 bit health parameter, 0 if healthy, unhealth othersize [0=healthy] |
alert_flag | 1 = URA may be worse than indicated [0,1] |
anti_spoof | anti-spoof flag from 0=off, 1=on [0,1] |
code_on_L2 | 0=reserved, 1=P code on L2, 2=C/A on L2 [0,1,2] |
ura | User Range Accuracy lookup code, 0 is excellent, 15 is use at own risk [0-15], see p. 83 GPSICD200C |
L2_P_data_flag | flag indicating if P is on L2 1=true [0,1] |
fit_interval_flag | fit interval flag (four hour interval or longer) 0=4 fours, 1=greater [0,1] |
age_of_data_offset | age of data offset [s] |
tgd | group delay [s] |
af2 | polynomial clock correction coefficient (rate of clock drift) [s/s^2] |
af1 | polynomial clock correction coefficient (clock drift) [s/s] |
af0 | polynomial clock correction coefficient (clock bias) [s] |
m0 | mean anomaly at reference time [rad] |
delta_n | mean motion difference from computed value [rad/s] |
ecc | eccentricity [] |
sqrta | square root of the semi-major axis [m^(1/2)] |
omega0 | longitude of ascending node of orbit plane at weekly epoch [rad] |
i0 | inclination angle at reference time [rad] |
w | argument of perigee [rad] |
omegadot | rate of right ascension [rad/s] |
idot | rate of inclination angle [rad/s] |
cuc | amplitude of the cosine harmonic correction term to the argument of latitude [rad] |
cus | amplitude of the sine harmonic correction term to the argument of latitude [rad] |
crc | amplitude of the cosine harmonic correction term to the orbit radius [m] |
crs | amplitude of the sine harmonic correction term to the orbit radius [m] |
cic | amplitude of the cosine harmonic correction term to the angle of inclination [rad] |
cis | amplitude of the sine harmonic correction term to the angle of inclination [rad] |