High-precision time comparison via satellite and observed discrepancy of synchronization

A time comparison experiment via a geostationary satellite was conducted between the stations in the USA and in Japan by a two-way method in SHF band using the Spread Spectrum Random Access communication system. With this system, a high resolution of about 1 ns was obtained in the measurements. The light synchronization discrepancy in the rotating coordinate system of the earth was clearly observed. Making the correction for the error due to the discrepancy, the value measured via satellite coincided well with that obtained through the ground link within an uncertainty of a flying-clock measurement. The accuracy of this experiment was estimated to be about 10 ns.