Tyre pressure monitoring apparatus

摘要

A tyre pressure monitoring system comprises an initiator which is arranged to transmit an initiation signal, and at least one corresponding transducer associated with a tyre of the vehicle which responds to exposure of the initiation signal from the initiator and is adapted to respond by transmitting a return signal indicating that it has been woken by the initiator, in which the strength of the initiation signal emitted by the initiator is varied across a number of values within a range.