Vehicle-mounted communication apparatus provided with a frequency selection function

摘要

PROBLEM TO BE SOLVED: To speed up the judgment time of a frequency by setting a detection period to a value for shortening time to FCM detection, which is the time except for one in the integer of the control signal transmission period of a base station, at the time of waiting FCM reception while a reception channel is switched at every prescribed detection time. ;SOLUTION: A reception channel is set to a down channel A with the control of a frequency control part 107 and FCM reception is waited. When the FCM reception cannot be executed after detection time which is previously decided, the reception channel is switched to a down channel B and is set. Since the FCM reception is not executed when on-vehicle communication equipment is out of a base station communication area, the reception channel is switched at every detection time and reception is continuously waited. The detection time is necessary to be longer than one slot time length since a signal is necessary to be continuously received in an FCM signal transmission period. FCM is received with the invasion of a vehicle to the communication area. A frequency judgment processing is terminated with the reception channel which is set at that time, a base station signal is received and communication is executed.;COPYRIGHT: (C)2000,JPO