Antenna amplifier module, function - GF82.62-P-3105-04R

Filtering and amplification of AM, FM, TV, and RRCL signals 

Right antenna amplifier module (A2/65). 

In the right antenna amplifier module (A2/65) the FM frequency bands (FM3 and FM4) and TV frequency bands (TV3 and TV4) are filtered out and amplified. In addition to this the RRCL frequency band is filtered out.

Demodulation and digitization of the RRCL signal 

The demodulator is located in the right antenna amplifier module (A2/65).

During demodulation the useful signal (RRCL signal) is generated from the RF signal.

The useful signal is digitized and sent over a separate data line to the overhead control panel control unit (N70). The RRCL signal is sent over the overhead control panel control unit (N70) to the CAN interior (CAN-B).

Left antenna amplifier module (A2/64) 

In the left antenna amplifier module (A2/64) the FM (FM1 and FM2) and TV (TV1 and TV2) frequency bands are filtered out and amplified and the AM signal filtered out.

Antenna diversity, function 

The diversity processor integrated into the left antenna amplifier module (A2/64)  serves for switching over between the FM antennas (FM1 up to FM4) in the windshield depending on the reception to obtain best possible reception.

• First the radio (A2) or the COMAND operating, display and control unit (A40/3) receive the signals of the active FM antenna by the left antenna amplifier module (A2/64)
• The radio (A2) or COMAND operating, display and control unit (A40/3) uses the incoming FM signals to generate the IF reference signal. This reference signal is transmitted to the left antenna amplifier module (A2/64) via a separate line
• After demodulation of the IF signal the diversity processor in the left antenna amplifier module (A2/64) checks whether the signal is free of interference. If interference is present it automatically switches on to the next of the four FM antennas in the windshield.
• Thereby the switchover speed depends on the frequency of the interference occurring. This prevents continuous switching between the antennas in areas where the FM reception is very poor which itself could result in interference to reception.
• A DC signal on the IF line in the left antenna amplifier module (A2/64) is switched to AM reception or to FM diversity.
• In the AM mode the FM diversity is not needed. The FM background reception is accomplished via the main FM 1 antenna
• For diagnosis purposes the DC signal in the left antenna amplifier module (A2/64) can be used to switch off AM reception.