Orban Optimod-PC 1101, Руководство по эксплуатации

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2-26
INSTALLATION ORBAN MODEL 1101
OPTIMOD-PC can process audio for transmission on a preemphasized ana-
log television aural carrier because this application requires lighter proc-
essing than FM radio. OPTIMOD-PC’s TVAxxxx factory presets have been
created for this application. See
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
sibilance and cymbals. The cure is lowering the
L
IMITER
D
RIVE
control un-
til the problem is no longer audible.
If you find that lowering the
L
IMITER
Drive causes too much loudness
loss, you can use the Band 5 compressor as a high frequency limiter to
compromise between loudness and limiting artifacts. Set B5
D
ELTA
R
ELEASE
to +6 and B5 S
TEREO
C
OUPLING
to O
FF
. Adjust B5 T
HRESHOLD
control until you
see gain reduction on the Band 5 GR meter with problematic material.
Continue to lower the B5
T
HRESHOLD
control until you no longer hear gain
pumping. Instead, you will probably hear some high frequency loss. This
loss is less subjectively objectionable than gain pumping.
You can use the AGC+LIMITER and TVA factory presets as examples of
how to do this. See AGC+[FLAT, 50
μ
s, 75
μ
s] LIMIT on page 3-24.
6. In Dolby Digital® applications only, set output and Dialnorm parame-
ters.
These parameters are only relevant to applications where OPTIMOD-PC is driving
a Dolby Digital transmission channel. They allow you to ensure that your audio
has the correct loudness compared to other correctly set up Dolby Digital chan-
nels. To make your transmission compliant with the EUBR128 and ATSC A/85
loudness control standards (and thus with the CALM Act), you must execute the
procedures in this step.
The 1101 works easily with Dolby Digital® transmission systems if you do one
crucial thing: You must tell the 1101 what value of Dolby Digital Dialnorm meta-
data you are transmitting to your audience. This will prevent your transmission
from being too loud or quiet compared to other correctly set up Dolby Digital
transmissions.
ATSC A/85 recommends using a Dialnorm value of –24 dB and EBU R128 recom-
mends –23 dB. The Dialnorm value is also the target loudness (in units of LKFS
[ATSC] or LUFS [ITU-R]) as measured on an ITU-R BS.1770-2 compliant loudness
meter.
Your Dolby Digital transmission’s loudness will automatically be correct if:
•
you use a “TV” factory preset (see Sound for Picture Presets on page 3-32),
•
you have adjusted the 1101’s Processor Mixer drive level so that the processing
operates with normal amounts of gain reduction (step 4 on page 2-36),
•
you have assigned the D
IALNORM
O
UTPUT
( in the C
ONFIGURATION
tab of the I/O
mixer
)
to the 1101 output driving the Dolby Digital channel