MODEL GPS-XL The Single Board GPS Time & Frequency Solution

Chad Gillease and Bruce Penrod

Abstract:	TrueTime is a leading manufacturer of high quality, cost effective precision time and frequency products. True- Time has served the worldwide market for over thirty-five years. For precision time, frequency and position requirements, GPS is the answer. The GPS provides twenty-four hour, worldwide coverage which is not affected by weather conditions. The coverage of twenty-four satellites in combination with numerous ground monitoring/verifling stations produce state of the art reliability and perfor- mance. TrueTime has introduced a family of high performance, low cost GPS Time and Frequency Receivers based on the versatile Model GPS-XL, a module composed of a six- channel GPS core receiver mated to a universal time and frequency host. Developed as an OEM module to be integrated directly into the user’s system, the GPS-XL specifically addresses the stringent requirements for accuracy and reliability required by the time and frequency community. Performance under the effects of Selective Availabilty (SA) includes 150 nanosecond UTC timing, 3 x lo-” frequency accuracy, and 3 to 5 meter differential positioning capabilities. Being a full-featured unit, the GPS-XL provides a variety of standard outputs and interfaces including IRIG-B, I PPS and RS-232. Optional outputs include 1, 5, and 10 MHz or 1.544 MHz or 2.048 MHz as well as RS-4221485. In addition to sourcing precision time and frequency signals, the GPS-XL module provides UTC referenced measurements of external signals: precision frequency measurements and precision time interval or event time- tag measurements. In its capacity as a high performance unit, the GPS-XL serves precision power utility applications such as power line fault location and voltage phase angle measurements. Telecommunications applications include wireless commu- nications cell site synchronization as well as precision frequency control for Stratum I Primary Reference Sources. Calibration applications routinely make use of the precision measurement and generation capabilities of the GPS-XL. The versatility of the GPS-XL module makes possible the Model GPS-705, a version in a miniature, ruggedized housing, the Model GPS-FPC, a battery powered field portable implementation in a weatherproof housing, and the Model XL-DC family of 19” rack-mountable units. The performance levels achieved by the GPS-XL are the result of a complete strategy based on accurate position determination, system integrity monitoring and muhi- satellite ensembling techniques. Performance data show the result of this strategy on the final outputs for various oscillators.
Published in:	Proceedings of the 7th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1994) September 20 - 23, 1994 Salt Palace Convention Center Salt Lake City, UT
Pages:	1055 - 1059
Cite this article:	Gillease, Chad, Penrod, Bruce, "MODEL GPS-XL The Single Board GPS Time & Frequency Solution," Proceedings of the 7th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1994), Salt Lake City, UT, September 1994, pp. 1055-1059.
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