Enhancements to the TTS-502 Time Transfer System

A.J. Van Dierendonck, Q.D. Hua

Abstract: Two years ago STI introduced an affordable, relatively compact time transfer system on the market -- the TTS-502, and described that system at the 1981 PTTI conference. Over the past few months, that system has been improved, and new features have been added. In addition, new options have been made available to further enhance the capabilities of the system. These enhancements include the addition of a positioning algorithm and new options providing a corrected 5 MHz output that is phase coherent with the 1 pps output, and providing an internal Rubidium Oscillator. The Positioning Algorithm was developed because not all time transfer users had the luxury of the Defense Mapping Agency's (DMA) services for determining their position in WGS-72 coordinates. The enhanced TTS-502 determines the GPS position anywhere in the world, independent of how many GPS satellites are concurrently visible. However, convergence time to a solution is inversely proportional to the number of satellites concurrently visible and the quality of frequency standard used in conjunction with the TTS-502. Real world solution results will be presented for a variety of cases and satellite scheduling scenarios. Typically, positioning accuracies were achieved better than 5 to 10 meters r.s.5. using the CIA code only at Sunnyvale, California. A Time and Frequency Solution allows for the output of a time corrected 1 pps (to GPS time or UTC) and a frequency corrected 5 MHz (and 1 MHz) signal that is coherent to the 1 pps. This is offered as an inexpensive option. To make the TTS-502 a stand alone system somewhat independent of GPS satellite visibility, an option is also offered where an internal Rubidium Standard is included in the TTS-502, eliminating the need for expensive Cesium frequency standards. This paper presents various details and results of the Positioning Algorithm and details of the new options available. In addition, details of other enhancements are described.
Published in: Proceedings of the 15th Annual Precise Time and Time Interval Systems and Applications Meeting
December 6 - 8, 1983
Naval Research Laboratory
Washington, DC
Pages: 133 - 154
Cite this article: Van Dierendonck, A.J., Hua, Q.D., "Enhancements to the TTS-502 Time Transfer System," Proceedings of the 15th Annual Precise Time and Time Interval Systems and Applications Meeting, Washington, DC, December 1983, pp. 133-154.
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