System functions

The following aerial system functions are described:

• Aerial diversity for FM aerials
• Diagnosis function for aerial diversity

Aerial diversity for FM aerials 

To ensure the best possible reception, aerial diversity works as follows:

• One of the aerials (FM 1) receives the required radio station.
• If the signal from this aerial deteriorates, the system switches to one of the other aerials (FM 2, FM 3, FM 4) with a stronger signal.

> E93

Depending on the position of the convertible hardtop (closed or open), aerial diversity will switch to either the aerials in the rear window or the aerials in the rear left and rear right side trim for radio reception.

The Convertible Top Module (CTM) records the position of the convertible hardtop. The CTM transmits a signal through a direct wire to aerial diversity.

Diagnosis function for aerial diversity 

Aerial diversity self-diagnosis comprises a check of the aerial inputs based on DC current measurement. In diagnosis mode, the AM/FM tuner switches each FM aerial on individually in turn.

AM reception can be evaluated with the AM amplifier switched on and off. A comparison of the results will produce the diagnosis output.