| 摘要 |
PROBLEM TO BE SOLVED: To surely perform zone switching at a radio base station, even at travelling at a fast speed. SOLUTION: This zone switching method has a device which detects a radio carrier during speech communication of a train station 7 that enters each radio base station 1, 2, etc., and a tone that is superimposed on the speech communication, sends a zone switching request signal to a central control unit 8 from the radio station, when both the radio carrier and the tone are detected on a level that is a prescribed value or more, and the unit 8 refers to a radio base station management table 11 and searches for a train that exists within the zone of the radio base stations that adjoin the radio base station. When the train station during speech communication exists only in one of both adjacent radio base stations, the zone switching is performed from the radio base station to the radio base station that makes a switching request and when the train station during speech communication exists in both adjacent radio base stations, the train number of the entering the train station is inquired to the train station, and the train station that undergoes zone switching is decided. |
