Telematic Communication Box (TCB): Microphone

Depending on the series and the vehicle equipment, two microphones (microphone and microphone 2) are installed in the left and right sides of the roofliner. The microphone installation location can vary depending on the vehicle type. The microphone on the driver's side is always used for an emergency call.

The microphones work with full duplex transmission. This means that the audio frequency signals are activated for both parties. It is thereby possible to speak and listen during the same call.

The microphone on the driver's side is connected to the Telematic Communication Box (TCB). The microphone signals are forwarded to the headunit for the hands-free mode of the telephone system.

The microphone 2 for speech processing (if part of the equipment) in the roofliner on the passenger's side is then directly connected to the headunit.

Fig 1: Identifying Microphone Components

Courtesy of BMW OF NORTH AMERICA, INC.