Orban Optimod-PC 1101, Operating Manual

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OPTIMOD-PC INSTALLATION
2-25
when compared to white PDF dither. It is therefore a good compromise
between white PDF dither and extreme noise shaping.
In many cases, you will not need to add dither because the source mate-
rial has already been correctly dithered. However, particularly if you use
the Noise Reduction feature, the processing can sometimes attenuate in-
put dither so that it is insufficient to dither the output correctly. In this
case, you should add dither within OPTIMOD-PC.
E) Set digital output format.
[AES3], [S/PDIF]
This control determines whether the status bits supplied at the digital
output are in Professional (AES3) or Consumer (S/PDIF) mode.
It does not affect the output level or source impedance, both of which
correspond to the AES3 standard.
5. Set preemphasis curve on which the look-ahead limiting operates.
[Flat], [50
µ
s], [75
µ
s]
Normally, OPTIMOD-PC will feed transmission channels that do not use
preemphasis and you should set this control
F
LAT
. 50
μ
S and 75
μ
S preem-
phasis are only useful if the 6300 is protecting a transmission link that
uses preemphasis (like certain satellite uplinks) or if you are using a
TVAxxx preset to drive an analog aural transmitter (i.e., one that pro-
duces a preemphasized FM aural carrier in analog television transmis-
sion). Use
F
LAT
preemphasis for Eureka 147, DRM, HD Radio, digital tele-
vision, netcasts, and any other channel that uses a lossy codec. When in
doubt, use
F
LAT
preemphasis.
For these applications, you can apply preemphasis to OPTIMOD-PC’s five-
band compressor’s sidechain (to make the five-band compressor “preem-
phasis-aware, allowing it to be used as a high-frequency limiter) and be-
fore OPTIMOD-PC’s look-ahead limiter so the limiter will control the
peaks of the preemphasized audio. A deemphasis filter after the look-
ahead limiter restores “flat” audio at OPTIMOD-PC’s output; it is assumed
that the transmitter driven by OPTIMOD-PC will restore the preemphasis
before the signal is transmitted. Note that the five-band compressor is
better than the two-band compressor in preemphasized applications be-
cause the two-band compressor cannot perform high frequency limiting.
When in doubt, choose F
LAT
operation.
Unlike OPTIMOD-FM and OPTIMOD-TV, OPTIMOD-PC cannot emit the
preemphasized signal, which would allow the transmitter’s preemphasis
filter to be bypassed. Instead, you must always use the transmitter’s built-
in preemphasis filter.
Because its processing is configured to be most effective with “flat me-
dia,” OPTIMOD-PC cannot provide extreme loudness for preemphasized
radio channels. Use one of Orban’s Optimod-FM processors for this appli-
cation.