Connecting A Ratings Encoder; Composite Output And Subcarrier Input - Orban OPTIMOD-FM 8500S Operating Manual

2-8
INSTALLATION

Connecting a Ratings Encoder

Composite Output and Subcarrier Input

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.
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. This embeds the ratings encoder between your Optimod's
left/right audio processing and stereo encoder, maintaining consistently high audio
drive levels into the ratings encoder while allowing your Optimod's composite lim-
iter to be used.
Activate the ratings encoder loop-through mode by setting the DO #2 Source con-
trol (Setup>I/O C
>DO2 C
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not detected at its SYNC input, your Optimod will automatically fall back to a direct
connection between the left/right audio processor output and the stereo encoder's
input, bypassing 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.
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 8500S'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
0Ω or 75Ω 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
given output to 75Ω, place the link on pins 1 and 2 of its associated jumper. (See the
schematic on page 6-38 and the parts locator diagram on page 6-34.)
Each output can drive up to 75Ω in parallel with 0.047μF before perform-
ance deteriorates significantly (see Figure 2-3 on page 2-9).
Connect the 8500S's composite output to the exciter input with up to 100 feet
(30.5m) of RG-58/U or RG-59/U coaxial cable terminated in BNC connectors.
Longer runs of coax may increase problems with noise, hum, and RF
pickup at the exciter. In general, the least troublesome installations place
) to R . In this mode, if a valid AES3 signal is
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