Orban OPTIMOD-FM 8600, Operating Manual

Page: 96 / 397

2-36
INSTALLATION ORBAN MODEL 8600
[In] or [Out]
It is wise to leave this control set to
I
N
.
When set to
I
N
, the 8600 adds “high-pass” dither before any truncation
of the output word. The amount of dither automatically tracks the set-
ting of the
W
ORD
L
ENGTH
control. This is first-order noise-shaped dither
that reduces added noise in the midrange considerably by comparison to
white PDF dither. However, unlike extreme noise shaping, it adds a max-
imum of 3 dB of excess total noise power when compared to white PDF
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 con-
nected 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
8600’s peak limiting system, thereby defining the maximum peak level