Time transfer using TV satellite TC2A

Summary form only given. TV signals from direct TV satellites have been used for time transfer in various experiments. The results of a previous experiment with satellite TDF2 led us to expect that this technique would allow remote atomic clock comparisons on continental (up to 1000 km) links, at an accuracy level of 10 ns. We show in this paper that the only obstacle to better results (5 ns or less) is the control of the equipment internal delays. This paper presents the results of a 6 week measurement campaign using slightly modified equipment and satellite TC2A. A theoretical estimation of the accuracy of the pseudo-ranging method that was applied is presented, and appears to be consistent with both (TDF2 and TC2A) experimental results. Experimental assessment of the accuracy has been performed using accurate GPS common view data from the 4 stations. Biases that were observed during the TDF2 experiment have been significantly reduced. As no re-calibration was performed after modification of the equipment, residual biases (ranging between 26 and 62 ns) were observed in the time transfer results. A new measurement session is currently being set up, including re-calibration of the 4 stations, with the final aim to obtain a consistency within a few ns with accurate GPS common-view data