On the Evaluation Test of the Navy Navigation Satellite System at the Fixed Station in Nagasaki Harbour

摘要

The purpose of this study was to obtain the fundamentals based on the results of this system and use them in testing other systems located in the ocean. When the positional errors from the station to the fixed positions by the NNSS were greater than a certain value, they were disregarded, and the calculated results by the remaining data showed similar accuracies as in the previous reports. Even when the data were classified by observed conditions, they gave very similar results except in the case of lower elevation angles. When the abandonment ranges were more than 0.6 nautical miles, the percentage of the abandoned data was 5.5%, and the percentage of unreliable data in each condition was greatest in the case of the elevation angles lower than 10°, next when the angles were higher than 60°. The percentage in the daytime was nearly 1.5 times as high as that in other time zones, and plenty of data showed errors of more than 5.0 nautical miles. Even the classification by the number of satellites indicates a range of errors from 3.5 to 7.1%, but we cannot argue that it is only due to the satellites, because such factors as evaluation angles and time zones are involved. When we use this system as the standard for the test of other systems, therefore, it is important to consider the percentage of unreliable data and also the observed positions.