Movement Sensor

Fig 1: Locating Mass Movement Sensor

Courtesy of VOLVO CARS CORPORATION

The Mass Movement Sensor detects movement in the passenger compartment using radio waves at 2.450 GHz. The Doppler effect principle is used to determine if the frequency of the received microwave has been modified in comparison to the transmitted microwave. Any change in frequency is interpreted as a movement in the car. When movement is detected, a trigger signal is sent to the upper electronic module which activates the alarm.

The movement sensor is located in the headlining in the center of the car. This allows the sensor to cover as large an area as possible.

There are diagnostics for the movement sensor.