About 8400Hd - Orban OPTIMOD 8400 Operating Manual

OPTIMOD-FM
2. Using a terminal program connected to the 8400's serial port #2:
A) Connect to your 8400 by following the instructions in Administering the 8400
through Serial Port #2 on page 2-46.
B) Follow instructions in steps 3 and 4 starting on page 2-49 to set the IP address and
subnet mask.

About 8400HD

The 8400 HD ("High Definition Digital Radio") option's output is designed to feed
streaming, netcasting, and digital radio channels, with particular emphasis on the iBiq-
uity® High Definition Radio system (formerly known as "IBOC"—"In-Band On-
Channel") approved for use in the United States.
The 8400 HD option consists of two circuit boards that are installed in your 8400 above
the existing DSP and input/output boards. The added DSP board implements the digital-
channel look-ahead limiter and other miscellaneous signal processing functions. The digi-
tal-channel input/output board adds an AES/EBU output, an AES/EBU sync input, and
left and right analog outputs. The analog outputs can be configured to emit the 8400's
low-latency monitor signal or to emit the signal that is processed for the HD digital chan-
nel.
An advanced-design look-ahead limiter that operates in parallel with the FM peak limit-
ing processes the signal at the added AES/EBU output. The look-ahead limiter (which
receives the 8400's "monitor" signal) is optimized to make the most of the limited bit-
rate codec (96 kbps) used in the High Definition Radio system's digital channel. By es-
chewing any clipping, the digital-channel output prevents the codec from wasting pre-
cious bits encoding clipping distortion products, instead allowing the codec to use its en-
tire bit budget to encode the desired program material.
The look-ahead limiter includes a parametric high frequency shelving equalizer that can
be placed either pre-gain reduction or post-gain reduction. You can use it to equalize tex-
ture disparities between the analog and digital channels and to reduce codec artifacts at
high frequencies.
15 kHz band limiting of the digital output also reduces codec artifacts. While the codec
used in the High Definition Radio system can provide a satisfying experience for the con-
sumer, at 96 kbps it is not audibly transparent—transparency would require a higher bit-
rate. By not wasting bits encoding the 15-20 kHz frequency range (which few radio lis-
teners can hear), the codec instead provides higher quality encoding of the crucial 20-
15,000 Hz band.
The HD output is designed to feed digital channels without pre-emphasis, which include
almost all such channels. The only high-quality digital channels using pre-emphasis of
which we are aware are NICAM channels (which use J.17 pre-emphasis) and some older
CDs (which use EIAJ—50µs/15µs shelving pre-emphasis). If you use the HD output to
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INSTALLATION