Author: Ekrem TUŞAT, Bayram TURGUT
Publishing Date: 2004
Volume 19 Issue 1
GPS system provides two types of ephemeris information for satellite orbits which are broadcast and precise ephemeris. Broadcast ephemeris is transmitted as a part of GPS navigation message and used in the applications that need real time positioning. It’s precision met accuracy requirement of this applications. However, for the applications requiring high accuracy, precise ephemeris data can be prefered during the post process of GPS observation. In this study, the effect of ephemeris data on the coordinate and baselines were investigated. For this reason a test network, which is constituted of 7 points and 12 baselines in the lengths of 7 to 90 km, is used. The process was done by using broadcast ephemeris transmitted as a part of navigation message on GPS observation collected and also precise ephemeris in SP3 format broadcasted on the internet by IGS. Consequently, the differences between the result obtained from both cases were compared and the effects of orbit data was explained on relative positioning.
Key Words: GPS; Broadcast ephemeris; precise ephemeris