CHAPTER 13: OPTICAL OUTPUT
MDU Solutions
®
– DVIS/DVISm - Digital Video Insertion System & Mini Digital Video Insertion System - Installation & Operation Manual
13-3
6. On the GUI
RF Output
tab, Figure 13-5, set the Attenuation value to 10dB. This will be the starting value to achieve
an optimal measured level at the
Modulator Output
RF port of +48dBmV. You may need to adjust the attenuation
value up/down due to tolerances and the 1dB attenuator steps.
7. After any attenuation settings changes, click the
Submit
button to save and apply the change before it is reflected
in the measured output.
8. Make any further attenuator refinements in the GUI under the
RF Output
tab to achieve an optimal level of +48dBmV
or as close as possible based on the 1dB attenuator steps.
WARNING
:
The
Modulator Output port will be the feed to the Optical Transmitter and must
never 48dBmV. A higher QAM level into the Optical Transmitter Card will overdrive the
transmitter and introduce distortions, i.e. degrade MER performance of resulting signal.
9. After having correctly set the QAM level at +48dBmV, disconnect the QAM Level Meter and connect a coaxial jumper
cable between the front panel
MODULATOR OUTPUT
port and the Optical Transmitter Card
RF IN
10. Connect the QAM Level Meter (still tuned to same QAM channel) to the Optical Transmitter Card -28dB RF Test Port,
RF TP
,
and m20dBmV.
NOTE: When +48dBmV is presented to the transmitter card the QAM level measured at the test
point shall be +20dBmV.
Use this test point while the DVISm is in operation to verify correct Optical Transmitter QAM drive level without disconnecting
the input cable to the optical transmitter
RF IN
.
6
7
Figure 13-5:
Set RF Attenuation
X
Remove this jumper
Install this jumper
9
Figure 13-6:
Install Jumper to Optical Transmitter
