Orban OPTIMOD-FM 8600, Operating Manual

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2-8
INSTALLATION ORBAN MODEL 8600
Per the AES3 standard, each digital input or output line carries both the
left and right stereo channels. The connection is 110
Ω
balanced. The
AES3 standard specifies a maximum cable length of 100 meters. While
almost any balanced, shielded cable will work for relatively short runs (5
meters or less), longer runs require used of 110
Ω
balanced cable like
Belden 1800B, 1801B (plenum rated), multi-pair 180xF, 185xF, or 78xxA.
Single-pair category 5, 5e, and 6 Ethernet cable will also work well if you
do not require shielding. (In most cases, the tight balance of Category
5/5e/6 cable makes shielding unnecessary.)
The AES3id standard is best for very long cable runs (up to 1000 meters).
This specifies 75
Ω
unbalanced coaxial cable, terminated in BNC connect-
ors. A 110
Ω
/75
Ω
balun transformer is required to interface an AES3id
connection to your Optimod’s digital input or output.
The digital input clip level is fixed at 0 dB relative to the maximum digital word. The
maximum digital input will make the 8600 input meters display 0 dB. The reference
level is adjustable using the Digital
R
EFERENCE
L
EVEL
control.
The 8600 is a “multirate” system whose internal sample rate is 64 kHz and multiples
thereof (up to 512 kHz). The outputs processed for analog FM are band-limited to
16.5 kHz, with a stopband that begins at 18 kHz. Therefore, the output can be
passed through a 44.1 kHz (or higher) uncompressed link without adding significant
overshoot. Because sample rate conversion is ordinarily a phase-linear process that
does not add bandwidth, the 8600’s output signal will continue to be compatible
with 44.1 kHz links even if it undergoes intermediate sample rate conversions (for
example, 44.1 kHz to 96 kHz to 44.1 kHz) at various points in the program chain.
The audio bandwidth of the AES output dedicated to the HD-processed signal is ad-
justable from 15 kHz to 20 kHz in 1 kHz steps.
Connecting a Ratings Encoder
This allows a ratings encoder having AES3 inputs and outputs to be driven from your
Optimod’s DIGITAL OUTPUT #2, while the rating encoder’s output drives your Opti-
mod’s SYNC INPUT. The ratings encoder may be embedded in one of two places:
•
At the output of the AGC before the analog-FM and HD processing paths split,
allowing a single ratings encoder to be used for both the analog FM and HD
channels while still receiving level-controlled audio. Set the
AES 2 S
OURCE
con-
trol to
AGC>R
ATINGS
in PC Remote or
AGC>RE
on the Optimod.
•
Between your Optimod’s left/right audio processing and stereo encoder, main-
taining consistently high audio drive levels into the ratings encoder while allow-
ing your Optimod’s composite limiter to be used. Set the
AES 2 S
OURCE
control
to
L
IMIT
>R
ATINGS
in PC Remote or
LIM>RE
on the Optimod.
In Rating Encoder mode, if a valid AES3 signal is not detected at its SYNC input, your
Optimod will automatically bypass the loop-through. While this will prevent dead
air, it means that ratings encoding will not be applied to your broadcast.