POSITIONAL ACCURACY OF GPS SATELLITE ALMANAC

How to accelerate signal acquisition and shorten starting time are key problems in the Global Positioning System (GPS). GPS satellite almanac plays an important role in signal reception period. Almanac accuracy directly affects the speed of GPS signal acquisition, the start time of the receiver, and even the system performance to some extent. Combined with precise ephemeris products released by the International GNSS Service (IGS), the authors analyse GPS satellite almanac from the first day to the third day in the 1805 th GPS week (from August 11 to 13, 2014 in the Gregorian calendar). The results show that mean of position errors in three-dimensional coordinate system varies from about 1 kilometer to 3 kilometers, which can satisfy the needs of common users.