OPTIMOD-FM DIGITAL
OPERATION
3-15
With the
FM
HD
C
ONTROL
C
OUPLING
set to
I
NDEPENDENT
,
there are several ap-
proaches to minimizing brightness and conditioning the signal to work well at low
bitrates.
Use little or no high frequency boost in the HD equalization and band mix sec-
tions.
Set the
HD
BAND
4>5
COUPLING
to
100%.
Set the
HD
B5
THRESH
to match the codec and its bitrate. Adjust the threshold
until you find a good compromise between presence and high frequency codec
artifacts. We find the range from -6.0 to +6.0 dB to be useful.
Use a moderate Band 5 attack time. 25 ms works well.
If necessary, lower the
HD
B4
THRESH
.
See
About the 8600S’s HD / Digital Radio Processing
complete description of the HD setup and subjective adjustment controls.
BS.1770 Compliance for Digital Radio
The 8600S includes an ITU-R BS.1770 Loudness Meter and Safety Limiter in the digi-
tal radio processing path. The Safety Limiter should only be activated if the regula-
tory authority in your country requires constraining BS.1770 Integrated Loudness to
a specified threshold. See step 12 on page 2-35.
Because it only offers processing for analog radio, model 8600SFM does
not include a BS.1770 Safety Limiter.
Input/Output Delay
The sophisticated look-ahead algorithms in the 8600S have one significant cost—the
input/output time delay is longer than that of an analog processor and can cause
problems if the if an off-air pickup is used to feed talent headphones.
To make intelligent decisions about how to process, the 8600S needs to look ahead
at the next part of the program waveform. (Slowly changing bass waveforms re-
quire particularly long look-ahead delays.) As digital on-air processing advances fur-
ther and further from its analog roots, this is the inevitable price of progress.
The amount of delay depends on several things. Because of their unprecedentedly
sophisticated processing, “MX” presets introduce delays of approximately 265 ms,
which makes real-time monitoring through headphones impossible for talent. The
8600S offers a low-delay headphone monitoring output to solve this problem, which
also occurs in HD Radio installation where the diversity delay is typically 8-10 sec-
onds.
If a non-MX preset is active, the delay is usually low enough to allow talent to moni-
tor live through headphone although a learning period may be required.
Summary of Contents for OPTIMOD-FM 8600S
Page 1: ...Operating Manual OPTIMOD FM 8600S Digital Audio Processor Version 2 1 Software ...
Page 7: ...Operating Manual OPTIMOD FM 8600S Digital Audio Processor Version 2 1 Software ...
Page 56: ......
Page 166: ......
Page 254: ...3 88 OPERATION ORBAN MODEL 8600S ...
Page 326: ......
Page 328: ...6 28 TECHNICAL DATA ORBAN MODEL 8600S CONTROL BOARD PARTS LOCATOR ...
Page 352: ...6 52 TECHNICAL DATA ORBAN MODEL 8600S ...