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The Accuracy and Coverage of Loran-C and of the Decca Navigator System — and the Fallacy of Fixed Errors

Published online by Cambridge University Press:  21 October 2009

David Last
David Last
Affiliation:
(University of Wales, Bangor)
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Abstract

The proposal to develop an extensive North-West European Loran-C system, replacing many existing chains of the Decca Navigator System (DNS), has led to an intensive debate on the merits of the two navigation aids, especially in the United Kingdom. The paper reviews the principal sources of random and systematic position errors in the two systems. The wide range of DNS random errors, predominantly due to skywave interference, are compared with the Loran-C random errors, and typical coverage limits of acceptable repeatable accuracy are presented. The paper also identifies the factors which control the magnitudes of Loran-C and DNS systematic effects due to land paths. It demonstrates that differences between the two systems are substantially less than are predicted by simple models. Loran-C and DNS techniques for dealing with land paths are compared and the errors experienced by Loran users are shown to be reduced by modelling and publishing ASF values.

This paper is based on a presentation made by the author at a technical symposium of the Wild Goose Association.

Keywords

Hyperbolic systemsRadionavigationErrors
Type
Research Article
Information
The Journal of Navigation , Volume 45 , Issue 1 , January 1992 , pp. 36 - 51
Copyright
Copyright © The Royal Institute of Navigation 1992

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References

REFERENCES

1Loran, C Working Group (NW Europe). (1985). Final Report.Google Scholar
2 The future of marine radionavigation in United Kingdom waters – a consultative document (1989). UK Department of Transport.Google Scholar
3 Megapulse Inc. (1988). Control of NW European Loran chains. Final report, Study for Trinity House, London, Contract E7029.Google Scholar
4Last, J. D. and Ward, N. W. (1989). Loran-C measurement trials in Ireland & UK– interference, noise & field strength results. proc. 18th Tech. Symp., Wild Goose Assoc, Hyannis, MA, USA, 29 Oct-1 Nov.Google Scholar
5Last, J. D., Farnworth, R. F. and Searle, M. D. (1990). A European Loran-C coverage prediction model. Proc. 19th Tech. Symp., Wild Goose Assoc, Long Beach, CA, USA, 23–2 5 Oct.Google Scholar
6Johler, J. R., Kellar, W. K. and Walters, L. C. (1956). Phase of the low radio-frequency ground wave. NBS Circular.Google Scholar
7Millington, G. (1949). Ground-wave propagation over an inhomogeneous smooth Earth. Proc. IEE, 98, Pt. III, 53.Google Scholar
8Pressey, B. G., Ashwell, G. E. and Fowler, C. S. (1953). The measurement of the phase velocity of ground-wave propagation of low frequencies over a land path. Proc. IEE, 100, Pt. Ill, 73Google Scholar
9Enge, P. W. and McCullough, J. (1988/9). Aiding GPS with calibrated Loran-C. Navigation (USA), 35, 4, 469, Winter.CrossRefGoogle Scholar
10Enge, P. W. (1989). Calibration of the proposed Loran-C chain for the United Kingdom. Private Comm.Google Scholar
11Gray, D. H. and Eaton, R. M., (1988). ASF chartlets - a picture is worth 1000 words.Proc.17th Tech. Symp., Wild Goose Assoc, Portland, OR, USA, 25–27 Oct.Google Scholar
12 Loran-C Working Group (NW Europe) (1989). Report.Google Scholar
13 Racal–Decca Marine Navigation Ltd. Marine Data Sheets. Updated periodically.Google Scholar
14Brunavs, P. (1977). Phase lags of the 100 kHz radio-frequency ground wave and approximate formulas for computation. Canadian Hydrographic Service Report.Google Scholar
15 Canadian Coast Guard. Loran-C data sheets. Updated periodically.Google Scholar