Orban OPTIMOD-FM 8600Si, Operating Manual

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1-2
INTRODUCTION ORBAN MODEL 8600Si
The rest of Section 1 explains how OPTIMOD-FM fits into the FM broadcast facility.
Section 2 explains how to install it. Section 3 tells how to operate OPTIMOD-FM. Sec-
tion 4 through Section 6 provides reference information.
OPTIMOD-FM was designed to deliver a high quality sound while simultaneously in-
creasing the average modulation of the channel substantially beyond that achiev-
able by “recording studio”-style compressors and limiters. Because such processing
can exaggerate flaws in the source material, it is very important that the
source au-
dio be as clean as possible.
For best results, feed OPTIMOD-FM unprocessed audio . No other audio processing is
necessary or desirable.
If you wish to place level protection prior to your studio / transmitter link (STL), use
the Orban Optimod 6300 or Optimod-PC 1101 or 1101e. These processors can be ad-
justed so that they substitute for the AGC circuitry in OPTIMOD-FM, which is then
defeated.
The 8600Si simultaneously processes for analog FM and digital channels like the
iBiquity™ HD Radio™ system, DAB, DRM, or netcasts. The 8600Si’s HD output pro-
vides look-ahead peak limiting that is optimized to make the most of limited bit-
rate codecs used in many digital radio systems. By eschewing any clipping, the HD
output prevents the codec from wasting precious bits encoding clipping distortion
products, allowing the codec to use its entire bit budget to encode the desired pro-
gram material.
Thanks to a base sample rate of 64 kHz throughout the 8600Si’s processing, the HD
output can be set for audio bandwidths between 15 and 20 kHz. Many codecs oper-
ate better when fed 15 kHz audio because this enables them to use their available
bit bandwidth most efficiently by concentrating on the part of the audio spectrum
that is critical to perceived audio quality. This is particularly true for low rates, like
32 kbps. However, at higher sample rates, full 20 kHz bandwidth provides the same
bandwidth as typical source material, so you may prefer to use it for rates of 96 kbps
and above.
The 8600SFM, which does not include digital radio processing, can be upgraded to
an 8600Si in the field via the 8600SiUPG upgrade kit, which can be purchased from
your Orban dealer. It is unnecessary to remove the 8600SFM from the rack when per-
forming the upgrade.
User-Friendly Interface
•
An LCD and full-time LED meters make setup, adjustment and programming
of OPTIMOD-FM easy — you can always see the metering while you are adjusting
the processor. Navigation is by dedicated buttons, soft buttons (whose functions
are context-sensitive), and a large rotary knob. The LEDs show all metering func-
tions of the processing structure (Two-Band or Five-Band) in use.