Entertainment Systems: Description and Operation

GF82.60-P-3109-02QB TV Tuner, Function
- with CODE (860) TV tuner


Receiver modules for audio and video
The TV system operates with a total of 3 receiver modules for image and sound signal processing. The tuners used cover a reception range of 30 to 866 MHz. The reception range is divided up internally into 3 bands:
^ Very High Fidelity (VHF) low
^ Very High Fidelity (VHF) high
^ Ultra High Fidelity (UHF)

Each band has its own controllable pre-stage. The sound outputs are carried out symmetrically. The TV tuner box has 4 antenna inputs, into which the signals are ideally fed from the vehicle antennas complementing one another.
The antennas are not assigned to a particular tuner but can be used in the same way by each tuner. Each receiver unit can independently select the most suitable input signal.

Audio/picture antenna diversity work separately from each other in order to minimize unpleasant interference noises or the picture being erased during reception on the move. The audio quality is limited to mono.

Multi standard signal processing
The signals from the TV tuner (A2/42) mixed to the IF (intermediate frequency) level are demodulated in the following signal processing. Both positive and negative amplitude-modulated signals can be processed. The division of the reception path into separate picture and sound processing is already prepared before demodulation by suitable choice of filters which separate the spectrum into picture and sound shares.
The picture signal is demodulated by active carrier recovery in a synchronous demodulator which is particularly low-distortion and has excellent intermodulation characteristics.

The TV tuner (A2/42) is designed for mobile television reception in various countries. It is connected directly to the COMAND operating, display and control unit (A40/3), via which the complete control of the TV tuner (A2/42) also takes place. The picture signals are transmitted via RGB outputs. The TV tuner (A2/42) does not have either its own controls or displays.
Basic controls of the TV tuner (A2/42):
^ Multi standard color (PAL, NTSC, Secam) 50/60 Hz sound and channel lists
^ Search aid with a maximum of 40 stations which can currently be received. These can be assigned individually and alphabetically to 10 program memory locations.
^ Playing part of a track, function
^ Teletext with page memory
^ Top text optional
^ Digital picture memory
^ Digital video processing
^ Adaptive Video quality evaluation
^ 4-fold antenna diversity, audio and video are separate
^ Audio antenna diversity
^ Video antenna diversity
^ Frequency diversity
^ Finding an alternative frequency
^ Depiction as picture in picture