Orban Optimod-FM 8300 Operating Manual page 176

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OPERATION ORBAN MODEL 8300
The control is located in the S screen because the regulation
/ S E
ETUP 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 8300. 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 1-13 and following pages.
Many paths have overshoot. This forces you to reduce the average modulation to
avoid overmodulating the transmitter. Reducing average modulation will reduce the
multiplex power by the same amount, forcing the multiplex power below the ITU
requirement.
To compensate for this, match the ITU412-9 control to the peak overshoot of the
transmission system following the 8300. For example, if RF peak deviation exceeds
the peak deviation produced by the 8300's sinewave oscillator (set for 100% modu-
Figure 3-1: Multiplex Power over 15 Minute Observation Interval
with MPX Power Controller Active, measured at Optimod's Composite Output