Land Coverage Analysis and Accuracy of the Loran-C NOCUS Chain in Western Canada

Gérard Lachapelle, B. Townsend and Ding-Sheng Chen

Abstract:	The Loran-C North Central U.S. (NOCUS) Chain became operational in mid-1991. Prior to that time, optimistic and pessimistic coverage analyses of the chain have resulted in significantly different coverages for Western Canada. In December 1991, the authors have conducted extensive Loran-C measurements in Western Canada to determine the effective coverage of NOCUS for land users and assess the effect of the secondary and additional secondary factors, SF and ASF, respectively, since unmodeled variations of these ultimately affect the absolute positioning accuracy of Loran- C. The tests were conducted in land vehicle mode along some 5,000 km of selected roads using LORCALZ (LORan CALibration at The University of CALgary), a DGPS-based Loran- C analysis system developed at The University of Calgary. Following a brief introduction to the anticipated NOCUS coverage in Western Canada, the methodology used and the field measurements made are described. An analysis of the Loran-C signal field strength (FS), Envelope-to-Cycle Differences (ECD) and signal to noise ratios (SNR) obtained during the tests is then presented. The continuous, i.e., year around, northern extent of NOCUS is estimated. The effect of the secondary and additional secondary factors on Loran-C time differences and positions is calculated through a comparison of GPS and Loran-C measurements.
Published in:	Proceedings of the 1992 National Technical Meeting of The Institute of Navigation January 27 - 29, 1992 Catamaran Resort Hotel San Diego, CA
Pages:	319 - 325
Cite this article:	Lachapelle, Gérard, Townsend, B., Chen, Ding-Sheng, "Land Coverage Analysis and Accuracy of the Loran-C NOCUS Chain in Western Canada," Proceedings of the 1992 National Technical Meeting of The Institute of Navigation, San Diego, CA, January 1992, pp. 319-325.
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