DISTRIBUTED ORBIT MODELING AND PROPAGATION METHOD FOR A PREDICTED AND REAL-TIME ASSISTED GPS SYSTEM

摘要

A distributed orbit and propagation method foruse in a predicted GPS or GNSS system, which includes apredicted GPS server (PGPS Server), a source of high accuracyorbit predictions (Orbit Server), a global reference network (GRNServer) providing real-time GPS or GNSS assistance data to thePGPS Server, a predicted GPS client (PGPS Client) running ona device equipped with a GPS or AGPS chipset. In responseto requests from the PGPS Client, the PGPS Server producesand disseminates an initial seed dataset consisting of currentsatellite orbit state vectors and orbit propagation modelcoefficients. This seed dataset enables the PGPS Client to locallypredict and propagate satellite orbits to a desired future time. Thispredictive assistance in turn helps accelerate Time To First Fix(TTFF), optimize position solution calculations and improvethe sensitivity of the GPS chip present on, or coupled with, thedevice. In contrast with other conventional predicted GPSsystems that forward large volumes of predicted orbits, syntheticephemeris or synthetic almanac data, this method optimallyreduces data transfer requirements to the client, and enables theclient to locally synthesize its own predicted assistance dataas needed. This method also supports seamless notification ofreal-time satellite integrity events and seamless integration ofpredicted assistance data with industry standard real-timeassistance data.