Time Transfer and the Sagnac Correction in the GPS

Abstract

Time transfer from a GPS satellite to a receiver fixed on the surface of the rotating Earth is investigated. Using experimentally confirmed GPS light signal transfer time and a simple kinematic calculation, light speed variation is demonstrated for light travelling between the satellite and the ground-based receiver. This variable speed is also determined using classical principles applied to light transmission relative to the terrestrial receiver moving as a result of the rotating Earth, all within the Earth-Centred Inertial (ECI) frame. These results produce the accurate time transfer algorithm without any correction and lead to the re-interpretation of the "Sagnac correction" considered by the ITU to be a necessary time correction in GPS time transfer. They also lead to a revision of the Lorentz Transformations that yields the Selleri Transformations which better accord with the observed light speed variation and confirmed relativistic phenomena in the physical world.