Tire condition monitoring system

A wheel transmitter unit, mountable to a wheel, for a tyre condition monitoring system, comprising:

• a sensor for sensing one or more parameters associated with the wheel;
• a transmitter for transmitting data representing the sensed one or more parameters;
• a power supply for supplying power to the sensor and the transmitter;
• and
• a condition monitor arranged to respond to operating conditions of the wheel transmitter unit to vary the manner in which the transmitter unit transmits data, wherein the condition monitor is operable to monitor the sensed parameters at closely spaced instances and to apply power to the transmitter for the transmission of data when there has been a significant change in the sensed parameters since the previous transmission of data.

A wheel transmitter unit, mountable to a wheel, for a tyre condition monitoring system, comprising:

• a sensor for sensing one or more parameters associated with the wheel;
• a transmitter for transmitting data representing the sensed one or more parameters;
• a power supply for supplying power to the sensor and the transmitter;
• a condition monitor arranged to respond to operating conditions of the wheel transmitter unit to vary the manner in which the transmitter unit transmits data;
• and
• a processor for processing signals from the sensor representing the sensed one or more parameters to produce parameter data, the processor being operable in a plurality of different modes including a calibration mode in which parameter data is recorded for known wheel conditions and a normal operating mode in which data representing the one or more sensed parameters is transmitted by the transmitter, wherein, in the calibration mode, pressure and temperature data are recorded for two different pressure conditions under the same temperature condition.

A wheel transmitter unit, mountable to a wheel, for a tyre condition monitoring system, comprising:

• a sensor for sensing one or more parameters associated with the wheel;
• a transmitter for transmitting data representing the sensed one or more parameters;
• a power supply for supplying power to the sensor and the transmitter;
• a condition monitor arranged to respond to operating conditions of the wheel transmitter unit to vary the manner in which the transmitter unit transmits data;
• and
• a processor for processing signals from the sensor representing the sensed one or more parameters to produce parameter data, the processor being operable in a plurality of different modes including a calibration mode in which parameter data is recorded for known wheel conditions and a normal operating mode in which data representing the one or more sensed parameters is transmitted by the transmitter, wherein the processor is arranged to produce timing information as part of the data for transmission and the timing information comprises a mark signal and a space signal which are transmitted prior to the transmission of the data representing the sensed one;
• or more parameters.