Geodetski Vestnik (Jan 2005)
Izračun položaja GPS-satelita iz podatkov preciznih efimerid : GPS-orbit computation from precise ephemeris data
Abstract
The article describes the theoretical point of view of the GPS precise ephemerides application that should be used in most precise GPS processing. Regarding broadcast, precise ephemerides allow us to achieve a much better accuracy of the final GPS processing results. There are several GPS services that via the internet interpose data in the standard form, but usually in the shortened form. This means that precise ephemeris data include only positional data, however in their complete form, GPS satellite-position and velocity data should be included. In this view there are different mathematical approaches of handling precise ephemeris data with the main goal of GPS satellite position computation. We will show the precise epehemeris data acquirement and its advantages and disadvantages. Further we will show different mathematical methods – numerical integration, interpolation and approximation – and their characteristics. Because the IGS service has done a step forward to solving the problem of time delay (in 2001) and to achieving a better initial accuracy we will use the IGS precise ephemerides in most practical examples.
