Functional description

Up to 2 aerials are in operation for the phase diversity. The aerial amplifier relays the amplified signals of the radio station received to the head unit via two separate signal lines. The first signal line carries the signals for AM and FM. The second aerial lead carries the 2nd FM signal. The radio signals are digitized in the headunit. Then the two radio signals are superimposed and added. The radio signals are mixed so the generated output signal has a better signal quality than the best of the individual input signals.

There are also aerial lines for the DAB aerial (frequency range: band III) The aerial amplifier amplifies the high-frequency signals (HF signals) from the individual aerials. The amplified aerial signals are transmitted to the head unit via separate leads.

The aerial amplifier was remote-fed. This means: The corresponding components in the aerial amplifier are supplied with voltage from the downstream device (e.g. headunit) by means of inadvertent power feed via the aerial line.

Inadvertent power feed is an electronics term. Inadvertent power feed means that the device receives its power supply from remote systems (e.g. aerial amplifier) via leads which are actually for the purpose of transmitting the signal. This makes use of the fact that the aerial signal is transmitted as AC voltage. The superimposed direct current voltage supply has no effect on the signal.

Courtesy of BMW OF NORTH AMERICA, INC.