| 摘要 |
PROBLEM TO BE SOLVED: To speedily detect that equipment exists outside a communication service area to reduce power consumption, to speedily detect a channel and to simplify a processing for restoring equipment into the communication service area. SOLUTION: A received frequency control part 23 switches the frequency of a reception signal at a step width wider than the interval of a frequency where the center frequency of a channel can be set. A level measuring part 22 measures the strength of the received signal on the basis of a base band signal. Data showing the measured strength of the reception signal is stored in a storage part 24. Then, an operation control part 25 discriminates the presence or absence of a channel realizing communication from the measuring result of the strength of the reception signal stored in the storage part 2. The operation control part 25 discriminates the presence or absence of the channel by using a prescribed threshold T2 smaller than a threshold T1 for detecting that the center frequency of the channel matches the frequency of the received signal from the strength of the received signal. |
