COVERAGE OF A RADIO BEACON-BASED DIFFERENTIAL GPS NETWORK

Per K. Enge, Michael F. Ruane, Diane Langlais

Peer Reviewed

Abstract:	A radio beacon-based system is being investigated by the U.S. Coast Guard for the communication of differential GPS (DGPS) messages. This system would add a digitally modulated subcarrier to transmissions from existing marine radio beacons, which operate in the 285 kHz to 325 kHz band. The idea is attractive, because a well located and widespread radio beacon network is already in place. Additionally, the DGPS/radio beacon signal can be designed such that it should not interfere with the direction finders which normally use the radio beacons. Finally, the signal should be reliably received at appreciable distances, because error correcting codes and interleaving are used. In fact, this paper discusses the prediction of DGPS/radio beacon signal coverage. Several coverage charts are presented as examples. The paper also lists which major U.S. harbors (8 million tons of cargo per year or more) can and cannot be covered if the DGPS subcarrier is installed on existing, continuous-broadcast radio beacons. The achievable signal coverage depends on which error correcting code is used, and the paper analyzes coverage for a “rate I/Z” code and a “rate l/8” code.
Published in:	NAVIGATION: Journal of the Institute of Navigation, Volume 34, Number 4
Pages:	307 - 324
Cite this article:	Enge, Per K., Ruane, Michael F., Langlais, Diane, "COVERAGE OF A RADIO BEACON-BASED DIFFERENTIAL GPS NETWORK", NAVIGATION: Journal of The Institute of Navigation, Vol. 34, No. 4, Winter 1987-1988, pp. 307-324.
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