Orban OPTIMOD-FM 8700, Operating Manual

Page: 98 / 390

2-36
INSTALLATION ORBAN MODEL 8700i
dither. Thus, it is a good compromise between white PDF dither and ex-
treme noise shaping.
J) If you are using the AES2 output, repeat steps (D) through (I) for this output.
Its controls are located on the I
NPUT
/O
UTPUT
> O
UTPUT
2 screen.
K) If you are using the Ratings Encoder Loop-through feature, perform the fol-
lowing steps (see
Connecting a Ratings Encoder on page 2-8):
a) Set the
AES2 O
UT
S
OURCE
control to
AGC>R
ATINGS
or
L
IMIT
>R
ATINGS
.
b) Connect your Optimod’s AES2 output to the input of the ratings encoder.
c) Connect the ratings encoder’s output to your Optimod’s S
YNC
I
NPUT
.
Depending on whether you choose AGC >R
ATINGS
or L
IMIT
>R
ATINGS
, the
S
YNC
input is repurposed automatically to drive the input of the FM/HD
split point or your Optimod’s stereo encoder. AGC applies a controlled
audio level to the encoder and allows you to use one ratings encoder for
both FM and HD;
L
IMIT
applies the highest possible audio level to the rat-
ings encoder but requires two ratings encoders if you are transmitting
HD.
d) Set the AES2 output S
AMP
R
ATE
to 48 kHz.
e) Set the AES2 output W
RD
L
ENGTH
to 24-bit.

In Ratings Encoder Loop-through mode, you cannot use your Optimod’s
S
YNC
I
NPUT
to receive a sync reference signal. You can still lock your Opti-
mod’s output sample rate to a signal applied to its AES3 input.

The Ratings Encoder Loop-through mode has a standard fallback strategy:
To prevent an audio mute, your Optimod will automatically bypass the loop-
though if there is no valid AES3 signal at your Optimod’s Sync Input. When
this happens ratings encoding does not occur, so warnings will flash on both
the Optimod’s front panel and in PC Remote (if previously connected to your
Optimod). Nevertheless, we recommend monitoring the presence of valid
ratings encoding via the monitor supplied by the ratings provider.
L) Using a modulation monitor or modulation analyzer, adjust the outputs you
are using (analog and/or digital) to make the modulation monitor read 100%
modulation (usually

75 kHz deviation).
If you are using program material, make sure that the program material
is loud enough to produce peaks of frequent recurrence that hit the
8700i’s peak limiting system, thereby defining the maximum peak level
that the 8700i will produce. In the U.S., we recommend using 900

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 412-7, you may seldom see peaks hitting

75 kHz deviation. In