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Chapter 4: Omnia-3fm Turbo
This chapter presents additional installation and operation information specific to the Omnia-3fm Turbo
processor. An Omnia-3fm Turbo Block Diagram is shown below, and a Parameters Worksheet is included at the
end of this chapter. Use the Parameter Worksheet as a master sheet for photocopying so that the parameter
settings for any custom presets can be recorded. Presets can also be saved to your computer and printed using
the Omnia-3fm Turbo Remote Control software.
Processor Location
Believe or not, this is an important consideration! Where you choose to locate the processor—at the studio or at
the transmitter—can have a profound impact on the overall performance. We present a few considerations that
will aid in making this decision.
In most applications, installing the processor at the transmitter site provides a solid coupling between the
processor and the FM exciter. Since there is nothing between the processor and the exciter to degrade the
tightly-controlled output, modulation performance will be maximized. The drawback to this setup is that the
unit is located in a remote location that is usually a very noisy environment. However, having the unit located
afar is mitigated by Omnia-3fm Turbo’s remote control capability.
If the plan is to set up the processor at the studio, consideration must be given to these STL factors:
• Is the STL path a clean shot? If the path is noisy, especially if an analog composite STL is used,
unwanted composite noise can be added to the processed signal through the STL receiver, and that can waste
modulation and degrade sonic performance.
• Is the STL Discrete or Composite? Analog or Digital? If a discrete system is used, there must be a
provision for a stereo generator/encoder at the transmitter. In that instance, it is imperative that this stereo
generator/encoder not introduce any distortion or overshoot to the system. Most stand-alone stereo
generator/encoders employ some form of low pass filter and safety clipper. These sections can add distortion
and overshoot if not set up properly. This applies to the ones built into digital exciters as well. If a composite
STL is used, the multiplexed output of Omnia-3fm Turbo can be connected directly to the STL. At the
transmitter location, the composite receiver can be connected directly to the exciter. If the STL is discrete
digital and it employs “compression” (a data-reduction codec), the Omnia-3 must be located at the transmitter
site to avoid the overshoots, distortion and audible side-effects of feeding a codec with a tightly peak-controlled
and pre-emphasized signal. Newer discrete digital designs are un-compressed (linear) and can accept the pre-
emphasized output of the processor well.
• Overshoots: Some analog STL systems are known to generate overshoots due to their design
deficiencies. One known culprit is the “bounce” that can be created by an inefficient modulator/demodulator of
the STL system. This can steal 1 - 2 dB of modulation, and that’s lost loudness. A method to verify that a
composite STL system is free of overshoots is to connect a oscilloscope to the STL receiver and monitor the
composite waveform, paying special attention to the integrity of any low frequency square waves. Of interest is
the “squareness” of the low frequency waveform, and if there is any noticeable “grass” or “peaky” looking
waveforms that would exceed the peak level of the low frequency signals. The low frequency waveform should
