関東東方海域におけるGPSとロランCの相対誤差

摘要

We measured the relative errors between the position fixes obtained by GPS and those by Loran C system in the Northwest Pacific Ocean, especially off the eastcoast of the Kanto district. The measurements were taken on the training ship, the Kakuyo Maru, on a cruise from August to September, 1994. Since October, 1994, the new Loran C 8930 Chain system has became available. Therefore we evaluated the relative errors obtained by the old and the new system. Mean positions of the relative error between the position fixes obtained by GPS and those by 9970 Chain trended northeastward and north-north-westward and error (1σ) ellipses extended almost east and west. The maximum value of the major axise of ellipse was 120 m. The maximum positioning errors (average error + standard deviation) were 140～160 m. Mean positions by 8930 Chain trended west-north-westward and north-westward and the error ellipses extended north and south or were almost circles. The major axises of ellipses were less than 60 m or shorter than those by 9970 Chain.