Orban OPTIMOD 8400 - Delay Difference between Digital-Channel and FM Outputs; HD I;O Setup Controls

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INSTALLATION ORBAN Model 8400
feed a digital channel with pre-emphasis, you must allow extra headroom to compensate
for the unpredictable peak level changes that the pre-emphasis induces.
If the HD output is driving a channel without pre-emphasis, it will control peak levels
with an uncertainty of less than 1 dB. However, you may want to allow headroom to
compensate for data reduction-induced peak overshoots at the receiver, which might oth-
erwise cause clipping. In our experience, 2 dB is typically adequate for this task.
If not factory-installed, the HD kit comes with stand-alone instructions on how to field-
install it.
Delay Difference between Digital-Channel and FM Outputs
In order to make the receiver analog/digital crossfade free from comb filtering, the time
delays in the HD Radio’s analog and digital channels must have a fixed and predictable
offset, correctly implementing the HD Radio receiver’s “time diversity” processing. The
8400’s HD output’s delay is automatically adjusted so that it always exactly 10.500ms
longer than the FM output’s delay, regardless of the FM output’s delay (which can vary
depending on processing settings). Therefore, the HD Radio exciter should be preset to
compensate for this 10.5 ms offset between the FM output and HD output. Once this has
been done, the time diversity delay will always be correct even if you choose a different
8400 preset.
HD I/O Setup Controls
Located in Input/Output Screen 5
Section Label Control Name Values
Monitoring
Phone Src HD/FM Mon
Meter Sel FMOutLevel/HD GR
HD HF EQ Pre/Post
Analog Output
Out Source HDpre/HDpost/FM Mon
Out Level –6… +24 dBU
Digital Output
St./Mono Stereo/MonoL/MonoR/MonoSum
Out Level 0… –20 dBFS; 0.1 dB steps
Samp Rate 32kHz/44.1kHz/48 kHz
Word Leng 14/16/18/20/24 bits
Dither In/Out
Sync Internal/Sync In
Format AES/SPDIF
Monitoring
Phone Src (“Headphone Source”) determines the source feeding the 8400’s front-panel
headphone jack. You can select the digital-channel feed or the signal that feeds the FM
analog outputs. The latter will be either the fully processed FM feed or the FM low-delay
monitor feed, depending on how the FM analog output is configured.