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OPTIMOD-PC
OPTIMOD-PC can add "high-pass" dither before any truncation of the
output word. The amount of dither automatically tracks the setting of
the W
L
ORD
OPTIMOD-PC's dither is first-order noise shaped dither that adds less
noise in the midrange than white PDF dither. However, unlike extreme
noise shaping, it adds a maximum of 3dB of excess total noise power
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], [SPDIF]
This control determines whether the status bits supplied at the digital
output are in Professional (AES3) or Consumer (SPDIF) 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 µs], [75 µs]
Normally, OPTIMOD-PC will feed transmission channels that do not use
preemphasis and you should set this control F
channel uses preemphasis. (An example is an analog microwave studio-
transmitter link in broadcast applications.) For these applications, you can
apply preemphasis before OPTIMOD-PC's look-ahead limiter so it will
control the peaks of the preemphasized audio. A deemphasis filter after
the look-ahead limiter then restores "flat" audio at OPTIMOD-PC's out-
put; it is assumed that the transmitter driven by OPTIMOD-PC will restore
the preemphasis before the signal is transmitted.
When in doubt, choose F
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. For analog television with FM aural carrier(s), use Optimod-TV
8382.
When operated with preemphasis, the look-ahead limiter should only be
used for light protection limiting with a low duty cycle. Otherwise, you
may hear pumping on material with a lot of high frequency energy like
control.
ENGTH
operation.
LAT
. Rarely, the transmission
LAT
2-23
INSTALLATION
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