Orban OPTIMOD-FM 8700, Operating Manual

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OPTIMOD-FM DIGITAL OPERATION
3-85
Recalling that the MPX POWER LEVEL meter is calibrated so that it indicates 0 dB
when the composite output of the 8700i is a sinewave at –11.92615 dB below 100%
modulation, we conclude that our subcarrier at 4% injection will add 0.10694 dB to
the multiplex power. Another calculation (not shown) indicates that 10% injection
will add 0.62889 dB to the MPX power.
Multiplex Power Threshold: The 8700i provides a means to limit the integrated mul-
tiplex power to the ITU standard by a technique that allows you to use any preset
and to create customized presets freely. The multiplex power controller is adjusted
in the
I
NPUT
/
OUTPUT
> U
TILITIES
screen by the M
ULTIPLEX
P
OWER
T
HRESHOLD
control. Set
it O
FF
if your country does not enforce the standard.
The control is located in the I
NPUT
/
OUTPUT
> U
TILITIES
screen because the regulation
applies to all operation of the processor in a given installation.
If your country enforces the standard, you should set the control to complement the
amount of peak overshoot in the transmission system following the 8700i. Setting
the control at “0” will correctly control the multiplex power when there is no over-
shoot after the 8700i. This will typically be true when you are using your Optimod’s
Figure 3-7: Multiplex power over 15 minute observation interval
with Multiplex power controller active, measured at the Optimod’s composite output