| 摘要 |
A tyre condition monitoring system comprises a unit (1) having a sensor (2) for sensing pressure and temperature. The unit (1), which is mountable in a wheel of a vehicle comprises a voltage controlled oscillator (4) and a code generator (5) arranged such that a coded signal is generated in a time period related to the value of the pressure or temperature sensed by the sensor (2). The coded signal is transmitted from the unit (1) by a transmitter (8). In order to conserve power the unit (1) comprises a power supply (15) which is activated by a timer (16) from time to time causing the coded signal to be transmitted. A counter (11) monitors when the coded signal has been transmitted and, once transmitted, causes the power supply to be deactivated. A monitor circuit (18) continuously monitors for an unacceptable condition. An override circuit (19) responsive to the monitor (18) or to an external stimulus can also activate the power supply.
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