sp3-docu-GPS

说明：  Why do we need standardized orbit formats? Standard orbit formats provide many advantages, the most obvious being orbit exchange. ASCII and binary formats both satisfy this function, but ASCII does it with greater generality because binary formats are computer operating system dependent.
(The NGS standard GPS orbit format SP1 was introduced in Remondi (1985). After a few years of use, it was realized that enhancements would eventually be required. The "orbit type," the coordinate system, and the GPS week associated with the first epoch of the ephemeris file were added in a manner that did not impact the formats and existing software.)