Orban OPTIMOD-FM 8600Si, Operating Manual

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2-8
INSTALLATION ORBAN MODEL
The 8600Si is a “multirate” system whose internal sample rate is 64 kHz and multi-
ples 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 HD-processed signal is adjustable 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 AES3id 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>RATI
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>RATI
on the Optimod.
In Rating Encoder mode, if a valid AES3 signal is not detected at its AES3id 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.
Because of the importance of proper ratings encoder operation, your Optimod will
flash a warning on its screen and on PC Remote if it enters the fallback mode. This
will help detect potential failures in the ratings encoder hardware.
Composite Output and Subcarrier Input
There are two composite outputs . They carry the encoded stereo signal, the stereo
pilot tone, and any subcarriers that may have been applied to the 8600Si’s subcar-
rier inputs .
These are unbalanced, with the shell connected directly to chassis/circuit ground.
Each output’s level is independently adjustable from –12 dBu to +16.0 dBu.
The output impedance of composite 1 output and composite 2 output can be set to
0
Ω
or 75
Ω
via jumpers J7 and J8 respectively (located on the Composite/SCA daugh-
terboard). As shipped, the link is on pins 3 and 4, yielding 0
Ω
impedance. To reset a