Geometric location of points on the Earth's surface, as well as satellite positions, are determined in the geocentric frame(conventionally it is related to the center of Earth mass), using cartesian, spherical or
ellipsoidal coordinates.
The mathematical model that was used considers that the LV has the shape of a TPS and is based on
ellipsoidal coordinates, leading the surface area calculation to depend on three spatial variables.
To obtain the solution of this problem it is convenient to introduce the planar
ellipsoidal coordinates ([q.sub.1], [q.sub.2]) defined as
Through gathering the data from long period and processing them according to the highest standards, they give precise and reliable solutions (
ellipsoidal coordinates) of stations and enable reference systems realization.
where [phi], [lambda] are
ellipsoidal coordinates of the involved stations.
Deflection components determination consist in the comparison of astronomical coordinates: latitude and longitude and
ellipsoidal coordinates of the same point (Hofmann-Wellenhof and Moritz, 2006).