Video Module
Video Module
Video module
As of 07/12, the new generation of the video module (VM) is utilized.
The video module (VM) is a mobile reception optimized TV receiver for the following digital terrestrial TV standards:
- DVB-T: Digital Video Broadcasting - Terrestrial
- ISDB-T: Terrestrial Integrated Services Digital Broadcasting
- DTMB: Digital Terrestrial Multimedia Broadcast
- CMMB: China Multimedia Mobile Broadcasting
Depending on the national-market version, television programmes, radio programs and in addition teletext, EPG (Electronic Program Guide, German Electronic Program Guide) and BML (Broadcast Markup Language) can be received.
Depending on the vehicle equipment and the national-market version, the following video modules are installed:
- Video module DVB-T (European version):
For TV mode while stationary
- Video module DVB-T RSE (European version):
For TV mode while stationary and while driving
- Video module ISDB-T (Japanese version):
For TV mode while stationary
- Video module ISDB-T RSE (Japanese version):
For TV mode while stationary and while driving
- Video module DTMB/CMMB (Chinese version):
For TV mode while stationary
- Video module DTMB/CMMB RSE (Chinese version):
For TV mode while stationary and while driving
The rear seat entertainment system (= RSE, stands for "rear seat entertainment") is an optional equipment (SA).
Functional description
The TV function is realized in the video module (VM). The TV picture is displayed on the Central Information Display (CID) and, depending on the vehicle equipment, on the rear monitor.
The video module modulates the high-frequency aerial signal (HF signal) that is fed over two or three aerial inputs, to a digital baseband signal.
During the process, both of the inputs are used for the reception of the actual dialled-in programs in the video module with the two aerial inputs. This mechanism, called MRC (maximum ratio combining), combines both reception paths. With it, an optimal mobile receiving power is achieved. Station searches are not performed in the background while driving (list of stations update).
The video module performs the station searches when in standstill (driving speed below 5 km/h) during suitable reception conditions.
During suitable reception conditions, the video module with three aerial inputs uses the third aerial input for the station search in the background and thereby continuously updates the list of stations. In the process, the allocation between the aerial input and the reception paths for the station search (MRC function) of the video module is continuously reconfigured and is not firmly assigned.
All video modules try to maintain the currently selected station when changing to another service area (called: DAB/FM changeover). For the video module with two aerial inputs, the DAB/FM changeover can lead to a momentary break in reception due to the system architecture. For a video module with three aerial inputs, the DAB/FM changeover is virtually unnoticeable for the user.
For the Japanese version, the service 1-Seg (1 segment mode) is also supported in the ISDB-T.
The following graphic shows the slot for the decoding card on the reverse side of video module with the video module in the Japan version as an example.
Structure and inner electrical connection
The video module (VM) is connected to the vehicle electrical system and the MOST via a 12-pin plug connection with a MOST interface.
The video module transmits the picture signals via CVBS lines to the connected devices (e.g. video switch).
The rear power distribution box supplies the video module with terminal 30B.
Pin assignments
The graphic above shows only the supply and bus connection. The current pin assignment is recorded on the wiring diagrams in the ISTA diagnosis system.
Nominal values
Observe the following setpoint values for the video module (VM):
Size Value
Supply voltage 9 to 16 V
Temperature range -40 to 95 °C
Diagnosis instructions
Failure of the component
If the communication to the video switch fails, run the standard checks (global testing procedure). If there is an internal control unit fault, the following behaviour is to be expected:
- Fault entry in the video module (VM)
We can assume no liability for printing errors or inaccuracies in this document and reserve the right to introduce technical modifications at any time.