Multiplex Power Threshold - Orban OPTIMOD-FM 8500S Operating Manual

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OPERATION ORBAN MODEL 8500S

Multiplex Power Threshold

Your Optimod provides a means to limit the integrated multiplex power to the ITU
standard by a closed-loop technique that allows you to use any preset and to create
customized presets freely. The multiplex power controller is adjusted via the ITU412-
9 control (see step 1 on page 2-22). Set it OFF if your country does not enforce the
standard.
The control is located in the Setup > S screen because the regulation
E
TEREO NCODER
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 your Optimod. Set-
ting the control at "0" will correctly control the multiplex power when there is no
overshoot after the 8500S. This will typically be true when you are using your Opti-
mod's built-in stereo encoder to drive the transmitter directly.
Section 1 of this manual has an extensive discussion of overshoot in transmission
paths. See page 1-16 and following pages.
Many paths have overshoot, and this forces you to reduce the average modulation
Figure 3-3: Multiplex power over 15 minute observation interval
with Multiplex power controller active, measured at the Optimod's composite output