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Shared GNSS constants.
These are semantic constants used across multiple GNSS modules. A parity target may still keep a local alias or comment when the operation order of a formula matters, but the source value lives here so modules do not drift.
Constants§
- AU_KM
- Astronomical unit in kilometers, matching Skyfield’s AU convention.
- AU_M
- Astronomical unit in meters, matching
AU_KM. - AZIMUTH_
ZENITH_ EPS - Squared horizontal fraction of the unit line of sight below which the
topocentric azimuth is degenerate and is defined to be
0.0. - BDS_
EPOCH_ MINUS_ GPS_ EPOCH_ S - Seconds from the GPS epoch to the BeiDou epoch (2006-01-01).
- BDT_
MINUS_ TAI_ S - BeiDou time minus TAI, seconds.
- C_KM_S
- Speed of light in vacuum (km/s), exact SI value converted to kilometers.
- C_M_S
- Speed of light in vacuum (m/s), IS-GPS-200. Re-exported from the canonical core home so the value is defined once for the whole workspace.
- DAYS_
PER_ JULIAN_ YEAR - Days per Julian year.
- DEGREES_
PER_ CIRCLE - Degrees in one full circle.
- DEGREES_
PER_ SEMICIRCLE - Degrees in one semicircle.
- DEG_
TO_ RAD - Degrees to radians.
- F_
B1I_ HZ - BeiDou B1I carrier frequency (Hz).
- F_
B3I_ HZ - BeiDou B3I carrier frequency (Hz).
- F_E1_HZ
- Galileo E1 carrier frequency (Hz). GPS L1 shares this frequency.
- F_
E5A_ HZ - Galileo E5a carrier frequency (Hz).
- F_L1_HZ
- GPS L1 carrier frequency (Hz). Galileo E1 shares this frequency.
- F_L2_HZ
- GPS L2 carrier frequency (Hz).
- GM_
MOON_ KM3_ S2 - Lunar gravitational parameter (km^3/s^2), DE/IAU conventional value.
- GM_
SUN_ KM3_ S2 - Solar gravitational parameter (km^3/s^2), IAU 2015 Resolution B3.
- GPST_
MINUS_ BDT_ S - GPS Time minus BeiDou Time (seconds): BDT = GPST - 14 s.
- GPST_
MINUS_ TAI_ S - GPS/Galileo/QZSS system time minus TAI, seconds.
- GPS_
EPOCH_ TO_ J2000_ S - Seconds from GPS epoch (1980-01-06 00:00) to J2000 (2000-01-01 12:00).
- HALF_
WEEK_ S - Seconds in half a GNSS week, the rollover fold threshold.
- J2_
EARTH - Earth’s J2 coefficient used by the core force models.
- J3_
EARTH - Earth’s J3 unnormalized zonal coefficient from EGM96.
- J4_
EARTH - Earth’s J4 unnormalized zonal coefficient from EGM96.
- J5_
EARTH - Earth’s J5 unnormalized zonal coefficient from EGM96.
- J6_
EARTH - Earth’s J6 unnormalized zonal coefficient from EGM96.
- J2000_
JD - Julian Date of the J2000 epoch.
- KM_TO_M
- Kilometers to meters.
- MEAN_
EARTH_ RADIUS_ KM - Mean Earth radius used by spherical shell propagation and conical shadow (eclipse) models (km).
- MEAN_
EARTH_ RADIUS_ M - Mean Earth radius used by spherical shell propagation and conical shadow (eclipse) models (m).
- MICROSECONDS_
PER_ SECOND - Microseconds per second, floating point. Used where a microsecond count
is divided or multiplied as an
f64; kept distinct fromUS_TO_Sso the divide-by-1_000_000.0operation order is preserved bit-for-bit. - MM_
PER_ M - Millimeters per meter.
- M_
PER_ KM - Meters per kilometer.
- NS_TO_S
- Nanoseconds to seconds.
- OBSERVABLE_
TRANSMIT_ TIME_ ITERATIONS - Fixed transmit-time iterations for observable prediction.
- OMEGA_
E_ DOT_ RAD_ S - WGS84 Earth rotation rate used by GNSS Sagnac/transport terms (rad/s).
- RAD_
TO_ DEG - Radians to degrees.
- SECONDS_
PER_ DAY - Seconds per civil day.
- SECONDS_
PER_ HOUR - Seconds per civil hour.
- SECONDS_
PER_ MINUTE - Seconds per civil minute.
- SECONDS_
PER_ WEEK - Seconds per GNSS week.
- SOLAR_
RADIATION_ PRESSURE_ N_ M2 - Solar radiation pressure at 1 AU (N/m^2), the cannonball SRP convention.
- SP3_
DEFAULT_ PROVENANCE_ COMMENT - Default SP3 provenance comment emitted when a product has no comments.
- SPP_
TRANSMIT_ TIME_ ITERATIONS - Fixed transmit-time iterations for SPP residuals.
- US_TO_S
- Microseconds to seconds.
- WGS84_
A_ KM - WGS84 Earth equatorial radius (km).
- WGS84_
A_ M - WGS84 Earth equatorial radius (m).
- WGS84_
E2 - WGS84 first eccentricity squared.
- WGS84_F
- WGS84 flattening.