Orban OPTIMOD-FM 8600, Operating Manual

Page: 305 / 397

OPTIMOD-FM DIGITAL TROUBLESHOOTING
5-7
Do not match levels by adjusting the output level of the output driving the HD ex-
citer. Only use this control to match the peak levels of the Optimod output to the
exciter . In other words, if the exciter is set to clip when it receives at –3 dBFS, adjust
the Optimod output level to –3 dBFS. This uses all of the headroom available in the
transmission channel, minimizing the amount of look-ahead limiting that the Opti-
mod needs to do.
If you have accidentally turned on the BS.1770 Safety Limiter, this will cause the
loudness to be lower than expected in HD Radio applications. Turn it off. See step 10
on page 2-32.
Digital Radio Loudness Cannot be Set Using the Digital Output 100% Peak
Level Control
When the BS.1770 Safety Limiter is
ON
, adjusting the HD-assigned
100% P
EAK
L
EVEL
C
ONTROL
sets only the output headroom, not loudness. See step 10 on page 2-32.
Loudness Drops Momentarily During HD Radio Analog/Digital Crossfades
The analog and digital channels in your transmission path have reversed polarity
with respect to each other and a phase cancellation is occurring in the radio during
crossfades. You can correct this with the
HD P
OLARITY
or
FM P
OLARITY
controls. See
page 3-75.
HD Frequency Response is Limited to 15 kHz
The
HD B
ANDWIDTH
control might be set to 15 kHz. See page 3-75.
Even if the
HD B
ANDWIDTH
control is set to 20 kHz, bandwidth will be limited to 15
kHz if the HD output’s sample rate is set to 32 kHz and/or if the sample rate of the
audio applied to the 8600’s digital input is 32 kHz. 20 kHz response requires sample
rates to be set to 44.1 kHz or higher.
You Cannot Set Any Output to Emit an HD Signal
From the main menu, Locate to
S
YSTEM
S
ETUP
> D
IAGNOSTICS
to see if your unit is an
8600FM. The 8600FM is the same as the 8600 except that the 8600FM does not pro-
vide digital radio processing. The 8600FM can be upgraded to an 8600 in the field by
installing the plug-in CPU board contained in the 8600UPG/HD upgrade kit, which
can be purchased from your Orban dealer.
The Left and Right Audio Channels are Reversed at the Digital 1 or Digital 2
Outputs only
Your unit’s DSP board has a firmware bug that can be fixed in software. Refer to AES
Output L/R Channel Reversal Bug on page 6-13.
Loudness is unexpectedly low from the analog FM processing chain
The MPX Power Controller and/or analog FM processing chain BS.1770 Safety Limiter
may have been turned on accidentally. See step 12 on page 2-24 and step 13 on
page 2-25 .