Long term and long distance GPS time transfer corrected by measured ionospheric delay

In order to optimize GPS (Global Positioning System) time transfer over an intercontinental baseline (France to Japan, about 8800 km), the authors supplement commercial C/A code receivers with dual frequency codeless receivers designed to measure directly the ionospheric delay of the GPS signal. Using data accumulated over a period of two and a half years, it is shown that the long-term precision of time transfer can be improved through the use of these ionospheric measurements. >