Broadcast Ephemeris Accuracy Analysis for GPS Based on Precise Ephemeris

The accuracy of broadcast ephemeris is an important index of a satellite navigation system. The theory and method of precise ephemeris assessing broadcast ephemeris are introduced. The accuracy of GPS satellite broadcast ephemeris is assessed with the precise ones provided by IGS. The orbital coordinates of GPS broadcast ephemeris from 18th to 24th October 2013 are calculated. The analysis shows that during this time the GPS satellite broadcast ephemeris is reliable, accurate and safe as the whole, meanwhile the broadcast ephemeris accuracy is about 1 meter, better than nominal accuracy of 5 meters.