2. For both the Digital and Analog inputs, an “Audio failure” is defined as “any audio level remaining at or
below -37.5dBFS for at least 7 seconds”.
3. Audio must have actually been ‘detected’
first on an input before the Hunt process can function. Said
another way, if the Omnia is sitting on the workbench with no audio applied and the Auto and Hunt options
are enabled, nothing will happen. The Omnia needs to see valid audio FIRST before it can detect the
absence of audio and begin the Auto switch phase.
Note that the Input meters and Input Menu Source indications will change to follow the Input Source that is
currently selected whether it be manually selected by the user or controlled by the Auto Switch function.
High-Pass Filter
In most FM systems, subsonic frequencies in the input audio program should usually be rolled off to prevent
difficulties with certain exciters and STL systems. The Omnia-6EX has a third-order (18dB/Octave) high pass filter
with five selectable cutoff frequencies from 60 Hz down to 20 Hz. The factory default is “Out”, which means that
audio frequencies to well below 2Hz are passed through the system without attenuation. You may select one of the
other values that may be more appropriate for your system.
Phase Rotator
This section consists of two, cascaded second order 200 Hz all pass filter sections. Phase Rotators (also known as
Phase Scramblers) are commonly utilized to make asymmetrical waveforms (such as voice) more symmetrical. This
ensures that clipping occurs equally on positive and negative peaks, making better use of the symmetrical nature of
the FM modulation process. Phase rotation can make talent voice sound cleaner, but since it disturbs the phase
integrity of musical signals, music might sound more faithful to the original source if phase rotation is not used. Off
can be chosen if previous phase rotation has been performed in your system (in a microphone processor for
example) or to preserve the phase integrity of the original program as described above.
Pre-Emphasis (FM Mode Only)
For the transmission side of conventional FM broadcasting, some form of high-frequency boost, or pre-emphasis is
used. The most commonly used values of pre-emphasis are 50 and 75 µs (microseconds). For North and South
America, 75 µs is used. In Europe, Australia and New Zealand, 50 µs is employed. The factory default pre-emphasis
setting is 75 µs. The pre-emphasis selection affects the operation of the audio processing and is applied to the
composite, discrete, and digital outputs. The pre-emphasized signal at the Left/Right and digital outputs can be
restored to flat, if needed, by the De-Emphasis parameter selection.
To set the Pre-Emphasis, rotate the jog-wheel to highlight one of the three choices: Off, 50 µs or 75 µs. Click the
jog-wheel to set the pre-emphasis selection.
Note: Normally, the Off selection under the Pre-emphasis options would not be used in conventional FM
transmission applications, but is provided in instances where processing of a flat signal is desired. One example
would be when preprocessing prior to a satellite uplink in distributed radio networks.
Omnia-6ex Use and Operation Manual – V: 1.10
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