Orban Optimod-FM 8300 Operating Manual page 120

3-2
OPERATION

Escape button provides an escape from current screen and returns user to the
next higher-level screen. Repeatedly pressing Escape will always return you to
the Idle screen, which is at the top level of the screen hierarchy.

Input meters show the peak input level applied to the 8300's analog or digital
inputs with reference to 0 = digital full-scale. If the input meter's red segment
lights up, you are overdriving the 8300's analog to digital converter, which is a
very common cause of audible distortion.

AGC meter shows the gain reduction of the slow two-band AGC processing that
precedes the multi-band compressor. Full-scale is 25 dB gain reduction. You can
switch the meter so that it reads the gain reduction of the Master (above-200
Hz) band, the Bass (below-200Hz) band, or the difference between the gain re-
ductions in the Master and Bass bands. The meter mode always reverts to
when the user leaves Full Modify.
M
ASTER
The latter reading is useful for assessing the dynamic bass equalization
that the AGC produces and it helps you set the AGC BASS COUPLING
control.

Gate LED indicates gate activity, lighting when the input audio falls below the
threshold set by the AGC gate threshold control (via the Full Modify screen's
AGC G control). When this happens, the AGC's recovery time is slowed to
ATE
prevent noise rush-up during low-level passages.

Gain Reduction meters show the gain reduction in the multi-band compressor.
Full-scale is 25 dB gain reduction.
When the Multi-Band structure is operating, all the meters indicate gain
reduction. When the Two-Band structure is operating, the two leftmost
meters indicate gain reduction in the Master and Bass bands, while the
rightmost meters indicate the gain reduction in the two-band high fre-
quency limiter.

Multiplex Power / HD Gain Reduction meter is switchable via the M
control in S
F
UNCTION
the ITU412 Multiplex Power controller. It shows how much the MPX Power Con-
troller has reduced the clipper drive, thereby reducing the average power in the
processed audio. It will show no gain reduction unless the MPX Power Controller
is turned on. In HD GR mode, the meter indicates the larger of the gain reduc-
tions in the left and right channel look-ahead limiters for the HD Radio / digital
radio / netcast processing chain.

Composite meter shows the output level of the stereo encoder before the
composite output attenuators. The meter's reading is calibrated in percent
modulation.
. In M
P
ETUP ULTIPLEX OWER
ORBAN MODEL 8300
mode, it indicates the action of
ETER