PURPOSE: To judge a remote position with high reliability and flexibility and low cost by operating a position judgment unit(PDU) and a visual subscribing unit(VSU) through cooperation with a satellite type communication system.

CONSTITUTION: A communication infrastructure is constituted by a satellite 14 arranged on a low-air pole orbit 20, a center exchange office(CSO), and a ground control station(GCS) 18 and is connected to a wide communication exchange network (PSTN) 22. A number of radio subscriber device 30 subscribing into this communication system is partitioned into a voice subscribing unit (VSTN) 38 and a position judgment unit(PDU) 40, the PDU 40 is mounted on animal, marine buoy or the like, and that position data is received by means of a monitor office(MO) 28. To operate the subscriber device 30, a programming call is established through cooperation with a communication system, after a patrol plan has been received in this duration, a self position is judged and is compared with the patrol plan, deviation from the patrol plan is reported if the comparison does not match, and the operation reliability and flexibility are ensured. In addition, the use power is controlled, and the service life of a battery is expanded.