摘要 |
A measuring unit inputs a detection received signal and measures a received RSSI value as the detection received signal. A first comparator inputs a plurality of received RSSI values measured by the measuring unit and compares them with a predetermined threshold value. A signal difference deriving unit derives a relative relationship among the plurality of RSSI values. A second comparator compares the relative relationship with a predetermined value. If the first comparator and the second comparator detect any malfunction, a decision unit receives notification accordingly from the first comparator and the second comparator and finally judges the malfunction of communication functions associated therewith.
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