Orban OPTIMOD-FM 5518, Operating Manual

Page: 54 / 217

2-16
INSTALLATION ORBAN MODEL 5518
To comply with FCC Rules, set the modulation reduction to one-half the
injection of the associated subcarrier. For example, if your subcarrier in-
jection totals 20% from two 10% subcarriers, set
M
ODULATION
R
EDUCTION
1
TO
“5%” and
M
ODULATION
R
EDUCTION
2
to 5%. This will reduce your audio
modulation to 90% (100% – 5% – 5%). When you add back the 20%
modulation due to the subcarriers, you get the required 110% total
modulation.
The Modulation Reduction function is active as long as signal is applied
to its associated GPI input.
C) Program the GPI input(s).
a) Navigate to
Setup > Next > N
ETWORK
&R
EMOTE
> R
EMOTE
I
NTERFACE .
b) Using the
Next
button, scroll the screen until you see the button
corresponding to the GPI terminal you wish to program.
c) Hold down this button and turn the knob until you see
M
OD
. R
EDUCTION
1
or
M
OD
. R
EDUCTION
2
as desired.
To program clock-based automation to activate modulation reduction, follow
the instructions found in “Using Clock-Based Automation” on page 2-27.
18. Turn the 5518’s ITU-412 MPX power controller off.
If the MPX power controller is turned on, turn it off. When on, it causes
gain reduction that makes it impossible to set the AI and DI reference
level controls correctly with test tones generated by the equipment driv-
ing the 5518’s input. See step 29 on page 2-22.
19. Recall the ST ENC NO LIM preset.
A) Press the
Recall
button on the 5518’s front panel.
B) Turn the knob until
S
T
E
NC
N
O
L
IMIT is visible in the lower line of the display.
It is likely that the
S
T
E
NC
N
O
L
IMIT is already active because it is the only
factory preset in the 5518. However, user presets might exist unless your
5518 is brand new or has been reset to its factory defaults. (To set the
5518 to its factory defaults, see
If You Have Forgotten Your Passcode on
page 2-33.)
C) Press the
Recall Next
button.
The L/R protection limiting and composite limiter are now inactive. This
makes it easier to adjust modulation using a test tone.
20. Adjust the input to accept a flat or preemphasized signal.
Note for users of J.17 preemphasis: If you are using the digital input and
set it to
D
IGITAL
+J17
in step (7.B) on page 2-12, the 5518 will first apply
J.17 deemphasis to the digital input signal. It will then preemphasize it at
50 or 75 µs or leave it unchanged, following the setting of the
I
NPUT
P
RE
-
E
MPH CONTROL , as adjusted in the steps immediately below.
The J.17 option is rarely used; it applies mainly to NICAM links. You can
set most OPTIMOD-FMs to emit a J.17-preemphasized signal with or