PURPOSE: To make equipment compact and low cost and to make it possible to perform the measurement of a position highly accurately, without a complicated correcting circuit, by correcting phase deviation due to the gain of an amplifier circuit accurately.
CONSTITUTION: The received signals of radiowaves, which are transmitted from a plurality of stations, are amplified with an amplifier circuit 2 to required levels. The phase difference between the radiowaves, which are transmitted from the stations, is measured in a phase-difference measuring circuit 3. The received signal levels of the radiowaves are obtained as digital data in a received signal-level measuring means (A/D converter 10). Phase-correction-data generating means (RAM 7 and the like) generate correcting data for phase fluctuation characteristics with respect to the received signal levels, which are obtained with the A/D converter 10. A phase-difference correcting means (CPU) corrects the phase difference based on the phase correcting data, which are obtained with the RAM 7 and the like. Therefore, a complicated circuit, which corrects the phase different fluctuation in correspondence with gains, is not required. The equipment can be made compact and the cost can be made low. The highly accurate position measurement can thus be performed.
KITAHATA ASAO
MORIMURA KAZUYOSHI
YOSHIOKA SHUICHI
