船舶航行中におけるディジタルMCA無線をデータ伝送に利用したRTK-GPS測位

抄録

RTK-GPS is a real time positioning system of a few cm order of accuracy with carrier phase measurement of the radio waves from GPS satellites. The phase data, transmitted from the reference station, are necessary to deduce the positions. The service for RTK-GPS data dissemination has been operated experimentally since October in 1997 from several GPS-based control stations of GSI (Geographical Survey Institute in Japan) via a mobile communication system, called DMCA (Digital Multi-Channel Access). The authors tried RTK-GPS positioning simultaneously at a fixed point by two receivers with a single antenna, using different GPS-based stations, Nerima and Kawasaki, respectively via DMCA. The result shows that the both of 2drms are a few cm and the discrepancy between the averaged positions is a few cm. Although the base lines of both reference stations exceed 10 km, which is the boundary for the accurate positioning described in the instruction, the remarkable coincidence is obtained. Next, they tried the positioning on board a ship in Tokyo Bay under navigation. They confirmed that it worked well.