Ultrasonic interior movement detector

The ultrasonic interior movement detector (USIS) with the 2 ultrasonic interior sensors is installed in the roof operating unit. The 2 ultrasonic interior sensors monitor the passenger compartment. Both ultrasonic interior sensors are installed in the USIS funnel, which points to the passenger compartment.

The 2 ultrasonic interior sensors are motion detectors and together constitute a transmitter and receiver unit. One ultrasonic interior sensor works as the transmitter, the other as the receiver. Movement is detected if the reflection (echo) of the sound waves changes.

Fig 1: Identifying Ultrasonic Interior Movement Detector Components

Courtesy of BMW OF NORTH AMERICA, INC.