Orban OPTIMOD-FM 5518, Operating Manual

Page: 63 / 217

5518-FM DIGITAL INSTALLATION
2-25
6. Set analog output and configuration level.
(Usually, the analog output will not be used and you can skip this step. However,
the analog output can be useful in some facilities. See the notes in step 8 on
page 2-13.)
A) Navigate to
Setup > I/O C
ALIB
> A
NLG
O
UT
C
ALIB
> AO P
RE
-E
. Set the analog
output preemphasis to
P
RE
-
E (for preemphasis) or
F
LAT .
If you will use the analog output to drive a stereo encoder,
P
RE
-
E pro-
vides the best performance because the stereo encoder does not have to
restore the preemphasis. (Its magnitude and phase response may not per-
fectly complement that of the deemphasis applied by the 5518 to its
processed output when the 5518’s output is set
F
LAT . This can introduce
overshoots in the overall transmission chain.) However, if you cannot de-
feat the preemphasis in your stereo encoder or if you will use the analog
output for monitoring, set the output
F
LAT
.
If you are sending the analog output of the 5518 through a digital link
that uses lossy compression (like MPEG, APT-X, or Dolby), set the output
F
LAT
.
Lossy codecs cannot handle pre-emphasized signals.
B) Set the
AO S
OURCE to
FM
,
FM+D
ELAY
,
or
M
ONITOR
.
FM: This produces a fully peak-controlled output suitable for driving a
transmitter.
FM+Delay: This produces a fully peak-controlled output suitable for driv-
ing a transmitter. Up to 16 seconds of diversity delay can be applied to
this output. To set the amount of delay, refer to step (G) on page 2-24.
C) To set your on-air modulation, turn on the 100 Hz calibration tone and set it
to 100%.
The peak level at the analog output is now the same as the maximum
peak level under program conditions when the
AO P
RE
-
E
control is set to
P
RE
-
E and the
AO R
EF or
DO R
EF controls have been set correctly (step 22
on page 2-18 and step 23 on page 2-18).
This peak level should agree with the setting of the
AO 100%
control.
AO
100%
is equal to the RMS value of a sinewave whose peak value is equal
to the maximum peak output of the analog output under program con-
ditions if the
AO P
RE
-
E control is set to
P
RE
-
E
.
For example, when
AO P
RE
-
E
= +10.0 dBu, the peak output is 5.77 volts, which corresponds to a
sinewave whose RMS values is 4.08 volts. Program material peaks of fre-
quent recurrence will not exceed 5.77 volts peak.
See step (5.C) on page 2-24 for instructions on how to turn on the cali-
bration tone and set its frequency and level.
D) Using the
AO 100%
button, set the desired analog output level corresponding
to 100% modulation, using units of dBu (0 dBu = 0.775 Vrms).
The most accurate way to set this control is by observing a modulation
analyzer connected to your transmitter.
In the United States, F.C.C. Rules permit you to add 0.5% modulation for
every 1% increase in subcarrier injection. For example, if your subcarrier
injection totals 20%, you can set the total modulation to 110% (

82.5
kHz deviation). This implies that you must set the 5518’s composite out-