| 摘要 |
PROBLEM TO BE SOLVED: To provide a tire air-pressure monitor capable of accurately and certainly monitoring a communication state between a transmitter and a receiver. SOLUTION: Each time a transmitter 3 provided in a tire 2 of a vehicle 1 transmits data, the transmitter 3 generates a variable value sequentially updated according to a predetermined order, i.e., a second count value C2. The second count value C2 is transmitted as a part of the transmission data. A receiver 4 decides whether reception dropout occurred before present reception or not, according to whether the second count value C2 included in reception data is updated according to the predetermined order or not. The receiver 4 decides that the communication is abnormal when a reception dropout number E is not less than four that is an upper limit value, while deciding that the communication is normal when the reception dropout number E is less than four. As a result, the presence of the abnormality in the communication can be easily and certainly decide.
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