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INSTALLATION ORBAN Model 8400
In many cases, the source material has already been correctly dithered, so
you will not need to add dither and can set this control to
Out. However, par-
ticularly if you use the Noise Reduction feature, the processing can some-
times attenuate input dither to a point where it is insufficient to dither the
output correctly. In this case, you should add dither within the 8400.
I)
Set 8400 User Bits to receive or block user bits.
[pass] or [block]
If you want to transparently pass incoming user bits through to your 8400
digital output, set
User Bits to pass. Otherwise, set this parameter to block, in
which case the 8400 will transmit user bits as all zeros.
J)
Using a modulation monitor or modulation analyzer, adjust the outputs you are us-
ing (analog and/or digital) to make the modulation monitor read 100% modulation
(usually ±75 kHz deviation).
If you are using program material, make sure that the program material is
loud enough to produce peaks of frequent recurrence that hit the 8400’s peak
limiting system, thereby defining the maximum peak level that the 8400 will
produce. In the U.S., we recommend using 900μs peak weighting on the
peak modulation indicator, as permitted by F.C.C. rules. This will cause the
monitor to ignore very low energy overshoots and will result in the highest
peak modulation permitted by law.
In other countries, use a peak-indicating instrument as specified by the regu-
latory authority in your country.
If you are required to implement the average modulation limits specified by
ITU-R 412-7, you may seldom see peaks hitting ±75 kHz deviation. In this
case, we advise you to set the output level using the 8400’s reference 400Hz
tone.
In the United States, F.C.C. Rules permit you to add 0.5% modulation for
every 1% increase in subcarrier injection. For example, if your subcarrier in-
jection totals 20%, you can set the total modulation to 110% (±82.5 kHz de-
viation). This implies that you must set the 8400’s composite output level
for the equivalent of 90% modulation, not counting the subcarriers. (90% +
20% = 110%.) This will mean that pilot injection will be about 8% modula-
tion instead of the desired 9%. From the Input/Output: Composite screen,
adjust
Pilot Level control as necessary to produce 9% modulation (±6.75 kHz
deviation). This will ordinarily require you to set the
Pilot Level parameter to
“10%.”
In software versions below 1.0, the feature to change modulation level to
compensate for subcarriers is not yet implemented. If you are using such
software, we strongly urge you to upgrade to the latest version. You can
download it from www.orban.com
. Click “Downloads” and navigate to
the 8400 folder.
8. Configure Composite Outputs
[Skip this step if you are not using the composite baseband outputs.]
A) Navigate to the Input/Output: Composite screen.
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