IN DUBIO PRO GEO 3D space : Satellite orbits

From ephemeris or almanac data of GNSS satellites (e.g. GPS) discrete orbit points are computed at a specified time grid. The computation is based on the GPS Interface Specification IS-GPS-200 and the GALILEO Signal in Space Interface Control Document.

Load standards and approximate values for

Angle unit (a.u.) Note

≡ START Guide Deutsch Geodetic constants

Quantity	Value	Unit
geocentric gravitational constant (incl. atm.) `GM`		m³/s²
angular velocity of Earth´s rotation `ω_E`		a.u./s

≡ START Guide Deutsch Keplerian elements at reference time

Quantity	Value	Unit
orbital eccentricity `e`		-
		m\|s\|m/s
right ascension of asc. node at the beginning of the week `Ω_o`		a.u.
argument of perigee `ω`		a.u.
		a.u.
orbital inclination angle `i_o`		a.u.

≡ START Guide Deutsch Change rates and correction values

Quantity	Value	Unit
mean motion difference `Δn`		a.u./s
rate of right ascension `dΩ/dt`		a.u./s
rate of inclination angle `di/dt`		a.u./s

≡ START Guide Deutsch Amplitudes of harmonic correction terms

Quantity to be corrected	cos-Amplitude	sin-Amplitude	Unit
argument of latitude `u`			a.u.
orbit radius `r`			m
inclination angle `i`			a.u.

≡ START Guide Deutsch Time and orbit points to be computed

Quantity	Value	Unit
time of applic. of the ephemeris `t_oe`		s since
start time of orbit computation `t₁`		beginning
computation time increment `Δt`		of the week
number of points to be computed		-

≡ START Guide Deutsch Orbit point list

The system type is always ''XYZ righthanded''.
In the coordinate list time in s is .

1 more example

Did you know? The beginning of a GNSS week is always sunday 0:00:00 in the GNSS system time. Note that this time differs from the universal time coordinated (UTC) by leap seconds.

≡ START Guide Deutsch In the library

Author(s)	Title	Year	Type	Pages MByte
Global Positioning Systems Directorate	Interface specification IS-GPS-200	2018	Offi	224 0.1
European Space Agency	Signal in Space Interface Control Document	2016	Offi	88 0.1
Blewitt G	GPS and Space-Based Geodetic Methods	2015	Educ	33 4.8
Vermeer M	Methods of navigation	2013	Educ	122 0.1
Korth W	Satellitengeodäsie	2009	Educ	41 0.1
Seeber G	Satellite Geodesy	2003	Educ	612 0.1
Blewitt G	GPS Data Processing Methodology: From Theory to Applications	1998	Educ	37 0.2
Blewitt G	Basics of the GPS Technique: Observation Equations	1997	Educ	46 0.3

≡ START Guide Deutsch 3D space : Satellite orbits