Tire Pressure Sensor: Description and Operation

4432 - Wheel Transmitters

The wheel transmitter is secured to the metal valve with a self-locking Torx screw in the wheel rim. The additional weight of approx. 30 grams can be counterbalanced with counterweights, so that special wheels are not necessary. The wheel transmitter can also be re-used in case wheels are changed.

The following components are integrated in the wheel transmitter:
- Transmitting antenna
- Pressure sensor
- Temperature sensor
- Measuring and control electronics
- Battery

Pressure sensor, temperature sensor as well as the measuring and control electronics are integrated into one sensor unit.

Depending on the respective country version, two different carrier frequencies are used for radio transmission. The carrier frequency of 433 MHz is authorized in most countries. For some countries (e.g. in Asia or Africa) a carrier frequency of 315 MHz is used. The respective carrier frequency is printed on the sensors, antennas and control modules. It can also be identified by the part number. The tire pressure monitoring system only functions with system components that have the identical carrier frequency.

The North American market uses carrier frequency 433 MHz.

The following data is transmitted by the wheel transmitter:
- Individual identification number (ID)
- Current tire pressure (absolute pressure)
- Current tire air temperature
- Condition of the integrated battery
- As well as the status, synchronization and control data required for safe data transmission