GPS Time from a Low Cost PC Based GPS Receiver

Anthony R. Pratt

Abstract:	A low cost GPS Receiver has recently become available which can be mounted inside a Personal Computer (PC) and occupies one full sized slot. The normal I/O required by a GPS Receiver takes place on the 8 bit I/O bus to the PC. One interesting feature of this unit is the output of a 1 pulse per second (1 pps) signal aligned to GPS time. This is possible through some special circuits within the GPS Receiver. The paper describes the technique that been used to control the 1 pulse per second using GPS time. Measurements of time accuracy have been made at a number of Standards Laboratories. The results have been used to establish the accuracy of the XR4-PC. Graphs showing the time difference between GPS derived time through the XR4-PC and the local national standards are given in the paper. The results indicate performance better than 20 nanoseconds rms with respect to UTC. There are many applications for a highly accurate time standard located within a Personal Computer. These include the accurate time stamping of messages, of computer transactions as well as providing the time references for frequency agile communications systems. In the case of a radio telescope observatory, GPS time can be used in the correlation of signals from distant radio stars received at two or more observatory sites.
Published in:	Proceedings of the 4th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1991) September 11 - 13, 1991 Albuquerque, NM
Pages:	243 - 252
Cite this article:	Pratt, Anthony R., "GPS Time from a Low Cost PC Based GPS Receiver," Proceedings of the 4th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1991), Albuquerque, NM, September 1991, pp. 243-252.
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