Omnia 6 Use and Installation Guide – Version 1.00a
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Chapter 4
This chapter presents installation and operation information specific to the Omnia-6fm. A
Parameters Worksheet, located at the rear of this manual, may be photocopied to record
the parameter settings used for specific processing presets.
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 and your stations' loudness
on the dial. 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 no other transmission link between the processor and the
exciter to degrade the tightly controlled peak output levels, modulation performance and therefore
competitive loudness, will be maximized. The drawback to this setup is that the processor is located in what
is usually a remote, acoustically noisy, and electrically unfriendly environment. Omnia6-fm remote control
can be used to make processing changes from elsewhere.
If you plan to set up the processor at the studio, consideration must be given to these STL factors:
Analog STL Use
• Is the STL path a clean shot? If the path is noisy, or is plagued by fades, multipath, or other types of
interference (especially if a composite STL is used), unwanted noise will be added to your signal,
robbing you of loudness.
• Is the STL a Discrete or Composite system? 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 into the system. Most stand-alone stereo
generator/encoders employ some form of low pass filter and safety clipper. These sections can add
significant distortion and modulation overshoot if not set up properly. If a composite STL is used,
the multiplexed output of the Omnia-6fm can be connected directly to the STL. At the transmitter
location, the composite receiver can be directly connected to the exciter.
• Overshoots: Some analog STL systems, especially those manufactured before 1990, can generate
significant overshoots due to several possible design deficiencies. Subsonic “bounce” can be caused
by an AC coupled modulator/demodulator in the STL system, and this alone can cause 1 - 2 dB of
lost loudness. One method of verifying that a composite STL system is free of overshoots is to
connect an oscilloscope to the STL receiver and monitor the composite waveform, paying special
attention to the integrity of the low frequency square waves. Of particular interest is the “square-
ness” of the low frequency waveforms, and whether there is any noticeable “grass” or “peaky”
looking waveforms exceeding the peak level of the low frequency signals. The top of the low
frequency waveforms should look very “flat.” If the top appears to “tilt” in any manner, then there is
a low frequency deficiency in the STL system. (We’d offer further information here on the “how and
why” this occurs, but that could consume a whole chapter by itself!) Simply stated, the problem
