Cross Rate Synchronization of Loran-C Using the Global Positioning System

Per K. Enge, Gary Noseworthy

Abstract:	Currently Loran-C transmitters which are in different "group rate intervals" are not tightly synchronized. Consequently, Loran receivers can only compute time differences between stations in the same group rate interval (GRI). In other words, they require at least 2 received signals from each GRI they wish to use. If the receiver can receive many stations, then this limitation is not troublesome. However, if the receiver is near the edge of coverage or if a station has failed, then it can be helpful to remove this limitation and allow the receiver to compute cross rate time differences. The time transfer capability of the Global Positioning System is one way of accomplishing this cross rate synchronization. In this paper 1 we examine (by example) the impact of cross rate synchronization on Loran-C coverage. We do this by developing a Loran accuracy model and considering Loran coverage in the midwest after the "midcontinent gap" has been filled. We find that cross rate synchronization would be helpful especially if a transmitter has failed. In this paper, we concentrate on the impact of cross chain synchronization on Loran coverage. We give brief consideration to time of transmission control versus system area monitor control, and the combination of Loran and GPS lines of position in user equipment.
Published in:	Proceedings of the 1988 National Technical Meeting of The Institute of Navigation January 26 - 29, 1988 Santa Barbara, CA
Pages:	287 - 293
Cite this article:	Enge, Per K., Noseworthy, Gary, "Cross Rate Synchronization of Loran-C Using the Global Positioning System," Proceedings of the 1988 National Technical Meeting of The Institute of Navigation, Santa Barbara, CA, January 1988, pp. 287-293.
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