Reception modules for audio and video
The TV system operates with a total of 3 reception modules for picture processing and sound signal. 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 signals are fed from the car antennas which complement each other ideally.
The antennas are not allocated to a particular tuner but can be used in the same way by any tuner. Each receiver unit can independently select the most suitable input signal.
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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.
Multistandard signal processing
The mixed signals from the TV tuner (MOST) (A2/10) at the intermediate frequency (IF) level are demodulated in the following signal processing. Both positive as well as 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 the 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.
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The TV tuner (MOST) (A2/10) is designed for mobile television reception in various countries. It is connected to the COMAND operating, display and control unit (A40/3) via the Media Oriented System Transport (MOST), which is also used for complete control and data transfer. The TV tuner (MOST) (A2/10) does not have either its own controls or displays. It is directly operated via the COMAND operating, display and control unit (A40/3) or via a remote control. Basic controls of the TV tuner (MOST) (A2/10):
Multistandard 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 with 10 program memory locations
Play function
Video text with page memory
Top text optional
Digital picture memory
Digital video processing
Adaptive Video quality evaluation
4-fold antenna diversity, with separate audio and video
Audio antenna diversity
Video antenna diversity
Frequency diversity
Finding alternative frequencies
Representation as picture in picture