Evaluation and Correction of Loran-C Positions in Comparison with GPS Data

Abstract

Navigation by Loran-C was evaluated in comparison with GPS’s data during the Jean Charcot cruise for the French-Japanese cooperative project “Kaiko”. Simple overlapping mean of Loran-C positions for five minutes showed a good relative- accuracy of about 50 meters. Loran-C positions, however, showed systematic shift up to 1 kilometer due to propagation delay of Loran-C wave through land area. The value of the shift was measured in the south off the Japanese Islands, and it was found that the shift of Loran-C position can be corrected within an accuracy of about 100 meters inmost cases by use of the correction table prepared by the Hydrographic Department of Japan. Corrected Loran-C positions are very close to the positions obtained by GPS system (TI-4100). In such a special case as the Loran-C wave propagates over a high mountain area or along a long coastal line, the recommended correction procedure for propagation delay should be improved to correct lthe local effects (~200m). Dome of the test data obtained by other GPS receivers are also demonstrated.