Two Way Time Transfer Results at NRL and USNO

Ivan J. Galysh, G. Paul Landis

Abstract:	The Naval Research Laboratory (NRL) has developed a two way time transfer modem system for the United States Naval Observatory (USNO). Two modems in conjunction with a pair of Very Small Aperture Terminal (VSAT) and a communication satellite can achieve sub nanosecond time transfer. This performance is demonstrated by the results of testing at and between NRL and USNO. The modems use Code Division Multiple Access (CDMA) methods to separate their signals through a single path in the satellite. Each modem transmitted a different Pseudo Random Noise (PRN) code and received the others PRN code. High precision time transfer is possible with two wag methods because of reciprocity of many of the terms of the path and hardware delay between the two modems. The hardware description was given in a previous paper.
Published in:	Proceedings of the 24th Annual Precise Time and Time Interval Systems and Applications Meeting December 1 - 3, 1992 Ritz-Carlton Hotel McLean, Virginia
Pages:	231 - 242
Cite this article:	Galysh, Ivan J., Landis, G. Paul, "Two Way Time Transfer Results at NRL and USNO," Proceedings of the 24th Annual Precise Time and Time Interval Systems and Applications Meeting, McLean, Virginia, December 1992, pp. 231-242.
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