The Effect of WGS-72 Geopotential in the Navy Navigation Satellite System on Station Surveys.

摘要

To impart greater internal consistency to the Transit System, the WGS-72 geopotential was implemented in the Navy Navigation Satellite System in December 1975. Sites previously surveyed using Transit (APL 4.5 geopotential) exhibit shifts in their surveyed positions that depend on their geographic location. The shifts result because the satellite ephemerides are displaced by varying amounts dependent on their earth-fixed subtrack. The amount and character of the ephemeris and site shifts were investigated for four satellites and 16 receiving stations. Noting the dependence of the station position shifts on ephemeris differences when using the two different geopotential models (APL 4.5 versus WGS-72), a scheme was developed to produce an estimate of survey shifts that would be expected on a worldwide grid. The shifts exhibit a worldwide rms of about 4 m and reach a maximum of 15 m in the Indian Ocean area. The results presented include real data surveys at the TRANET and OPNET stations and the simulated surveys. (Author)