| 摘要 |
PROBLEM TO BE SOLVED: To improve the reliability of judgment result that the telephone set is outside the service area by detecting a bit error rate, comparing it with a prescribed threshold and judging that a device is out of the service area of a radio base station when the detected result exceeds the threshold. SOLUTION: A decoding part 3 decodes a speech signal SA from a reception signal obtained through an antenna 1 and a reception part 2, compares a bit string which is previously set with an actual bit string obtained from the speech signal SA, detects the bit error rate and outputs bit error rate data DB. An out-of-area judgment part 4 compares the actual bit error rate obtained from the bit error rate data DB with the threshold which is previously set. When the actual bit error rate does not exceed the threshold, the out-of-area judgment part 4 outputs no signal and an adder 6 outputs only the speech signal SA to a speaker 7. When the actual bit error rate exceeds the threshold, the out-of- area judgment part 4 outputs an out-of-area signal SK and an alarm signal generation part 5 generates an alarm signal SAL and outputs it to the adder 6. |
