Comparison Between Naval Surface Weapons Center and Navy Astronautics Group Ephemerides for GEOCEIVER Positioning.

摘要

Current procedures for GEOCEIVER positioning use GEOCEIVER tracking data in conjunction with Navy Navigation Satellite (NNS) ephemerides as produced by the Naval Surface Weapons Center (NSWC) and based on a worldwide tracking system. The Navy Astronautics Group (NAVASTROGRU) also produces ephemerides for these satellites in near real time but based on a four station tracking net (OPNET). These study results indicate that GEOCEIVER coordinate differences of about ten meters can be expected when the NAVASTROGRU ephemerides are substituted for the NSWC produced ephemerides. Orbit comparisons show Root Mean Square radial, intrack and crosstract differences averaging about 10, 25 and 15 meters, respectively. Although these differences could be reduced by applying a more suitable transformation to the NAVASTROGRU ephemerides, best agreement would be achieved if a common gravitational model and OPNET station coordinate set were used. This should be achieved when current plans to use the World Geodetic System 1972 gravitational model and OPNET station coordinate set in NAVASTROGRU ephemerides computations are implemented.