3
VMA 191
Part N
o
: 9228.8x/ .9x
Audio/ Video Modulator
A/V
→
ATV (AM)
A
LINE
1. Safety and operating instructions
When assembling, starting-up and adjusting the modules, it is necessary to consider the system specific references in
the manual instruction!
The modules may only be installed and started up by authorized technical personnel!
When assembling the modules into the receiving points, the adherence of the EMC regulations is to be secured!
The assembly and wiring have to be done without voltage!
With all work the defaults of the DIN EN 50083 have to be considered! Especially the safety relevant execution of the
DIN EN 60728-11 [1] is necessary!
The devices come under protection classification I. It is absolutely necessary, therefore, to insert the mains plug into a
socket with protective contact
2. Device variants
VMA 191
9228.82 A/V
→
IFI
→
ATV (AM) Norm B/G
VMA 191
9228.85 A/V
→
IFI
→
ATV (AM) Norm M
VMA 191
9228.91 A/V
→
IFI
→
ATV (AM) Norm D/K 1
*
VMA 191
9228.92 A/V
→
IFI
→
ATV (AM) Norm D/K 2
*
VMA 191
9228.94 A/V
→
IFI
→
ATV (AM) Norm D/K 4
*
* D/K 1:
standard
D/K with sound carrier 6.5 MHz and 6.25 MHz
D/K 2:
standard
D/K with sound carrier 6.5 MHz and 5.74 MHz
D/K 4:
standard
D/K with sound carrier 6.5 MHz
3. General
The Audio/ Video Modulator VMA 191 is a module of the head end system A-LINE which is conceived as a complete system for
big and middle-sized networks. The VMA 191 generates an analogue TV signal in whole cable frequency range.
4. Functional description
The video processing contains a video low pass with a sound trap, a group delay-pre-equalization, clamping circuit and a
switchable video AGC. The video AGC function requests one white pulse per field in any line within the source signal (white level
adjustment control); alternatively AGC has to be deactivated. The magnitude of the residual carrier is determined by video ampli-
tude of the input signal in this case. The audio processing contains a symmetric input amplifier, an audio low pass, a level setting
element and a switchable audio summing unit in the 9228.85 respectively a switchable stereo/ dual tone-coder otherwise. These
unit respectivly coder allows remote accesses manually, VPS controlled or via corresponding contacts into the audio socket
(see chapter 5.6). There is the possibility to configure an asymmetric audio input. An electronically switch connects pin 4 and 5
inside the device on ground. Analog video and audio signals are fed to separate modulators and summarized at IF mixer. After IF
filtering follows the conversion in the wanted output channel by the help of a duplex frequency conversion. The operation of high
level mixers and fractional N-PLL‘s assure a high output performance. The output channel is free adjustable between 45…862
MHz. The modulator is adjacent channel fitted. For level error reporting a reference level is generated internally and is compared
with current value permanently. After each programming of the level and/or frequency values an automatic measurement of the
reference level takes place. The monitoring of the input signal is done at the output of the VMA 191. If the IF loop is activated the
IF input is weighted.
The integrated management unit consists of the data interface for PC/LAN/WAN (IP/ Ethernet interface / RJ 45). The management
of the module can be done via PC/Laptop (see programming). The status of the module will displayed with LEDs (see section 5.2
”Meaning of the LED signals”). The IP address of each device can be edited and adjusted to the respective LAN.
