To locate a maintenance/inspection worker accurately without imposing any burden on the worker using a GPS(global positioning system) receiving unit and a mobile communication terminal.
A GPS antenna 21a and a GPS receiving unit 20a for receiving radio wave from a plurality of GPS satellites 2 are contained in a portable box 9 being carried by a maintenance/inspection worker. On the other hand, a GPS antenna 21b and a D-GPS receiving system 20b for measuring GPS position error are disposed in a fixed station, i.e., the computer network (LAN) 10 in a control center 1. Furthermore, a PHS terminal is contained in the portable box 9 in order to communicate information with the LAN 10 through a mobile communication line 3. A center computer 11 connected with the LAN 10 calculates the position of the portable box 9, and thereby the worker, based on positional information and D-GPS positional error received on the communication line 3.
MURATA KAZUO
INOUE HISATO
MATSUMOTO KOICHI
YOKOYA ICHIRO
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