To solve the problem of a communication failure due to crosstalks, in a tire monitoring system of a vehicle.

When an initiator 11 transmits a request signal to a sensor unit 30 of a tire 2, a comparison signal is transmitted from an initiator 12, corresponding to the tire 3 at a different timing, such as, timing immediately after the request signal is transmitted so as to prevent crosstalks that cause the sensor unit 30 of the tire 3 at a near position to respond to the request signal. Each sensor unit 30 measures the first physical quantity, such as, receiving strength of the request signal correlated with a first distance from the initiator 11 to the sensor unit, and the second physical quantity, such as, receiving strength of the comparison signal correlated with a second distance from the initiator 12 to the sensor unit, compares the first and second physical quantities, and implements an operation corresponding to the request signal, if it is determined that the second distance is larger than the first distance.

COPYRIGHT: (C)2011,JPO&INPIT