Orban OPTIMOD-FM 5700i, Operating Manual

Page: 88 / 335

2-32
INSTALLATION ORBAN MODEL
The most accurate way to set this control is by observing a modulation
analyzer connected to your transmitter.
If you have (inappropriately) set AO S
OURCE
: M
ONITOR
in step (B) above,
the peak level will not be well controlled because no peak limiting has
been applied to this signal. This will also be true if you have defeated the
final clipper (step 6 on page 2-28).
If you are using program material, make sure that the program material
is loud enough to produce peaks of frequent recurrence that hit the
5700i’s peak limiting system, thereby defining the maximum peak level
that the 5700i will produce. In the U.S., we recommend using 900
μ
s peak
weighting on the peak modulation indicator, as permitted by F.C.C. rules.
This will cause the monitor to ignore very low energy overshoots and will
result in the highest peak modulation permitted by law.
In other countries, use a peak-indicating instrument as specified by the
regulatory authority in your country.
If you are required to implement the average modulation limits specified
by ITU-R 412-9, you may seldom see peaks hitting
±
75 kHz deviation. In
this case, we advise you to set the output level by using the 5700i’s refer-
ence 100Hz tone.
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 5700i’s composite out-
put level for the equivalent of 90% modulation, not counting the subcar-
riers. (90% + 20% = 110%.) The pilot injection will thus be about 8%
modulation instead of the desired 9%. Adjust the
Setup > S
TEREO
E
NCODER
> Next > P
ILOT
L
VL
control as necessary to produce 9% modu-
lation (
±
6.75 kHz deviation). This will ordinarily require you to set the
P
ILOT
L
VL
parameter to “10%.”
11. Set digital output and configuration level.
[Skip this step if you will not be using the digital outputs.]
[See the notes in step 10 immediately above.]
A) Navigate to
Setup > I/O C
ALIB
> D
IG
O
UT
1 C
ALIB
.
B) Set the DO P
RE
-E control to P
RE
-E (for pre-emphasis), P
RE
+J17 , J.17 or F
LAT
.
C) Set the DO R
ATE
to 32, 44.1, 48, 88.2, or 96 kHz.
The 5700i’s fundamental sample rate is always 32 kHz, ensuring that the
output bandwidth is always strictly limited to 16 kHz and that the proc-
essed signal can be passed through a 32 kHz uncompressed STL without
addition of overshoot. However, the internal sample rate converter sets
the rate at the 5700i’s digital output. This adjustment allows you to set
the output sample rate to ensure compatibility with equipment requiring
a fixed sample rate.
D) Set the
P
ILOT
S
YNC
.
The
P
ILOT
S
YNC
control determines the reference frequency source to
which the 19 kHz pilot tone frequency is locked. (To do this, the DSP clock