The local restitution of GPS time at Shanghai Observatory

Local restitution of GPS time (LRGPST) at Shanghai Observatory (SO) is the synthesized results for GPS time with multi-satellites at UTC 0h. It is obtained by using the method of the cubic spline function to interpolate smooth and weight averaging for the GPS time comparison data received from a single satellite at a different moment. With calculated results from LRGPST data during 1995-1996, it shows that the effects of selective availability (SA) have basically been removed from the statistical characteristics whose level is similar to or a little better than the results of a single satellite without SA effects (such as PRN15). It can improve the long term reliability of international GPS time synchronization results. With comparison, the system deviation corrected value Δt for international GPS time synchronization in [BIPM-SO] and [USNO-SO] are about +3.7 ns and +21.0 ns respectively. Their uncertainty are 7.2 ns and 8.8 ns respectively