Omnia Audio Omnia.11 - Manual (Page 46)

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FM Options
There are 3 groups of controls here Pre-Emphasis, BS-412 and Diversity Delay.
Pre-Emphasis 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, AES/EBU digital and
Livewire FM channel outputs. The HD channel
outputs are never pre-emphasized.
FM Options Submenu (Basic Tab)
The pre-emphasized signal at the Left/Right Analog XLR, AES/EBU digital and Livewire outputs can be restored to
flat, if needed (such as for monitoring), by the De-Emphasis control in each of the respective output groups.
There are three choices for pre-emphasis in the drop-down control: Off, 50 µs or 75 µs. Be sure to select the pre-
emphasis that is correct for your country.
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.
ITU BS-412 Power Limiter
In certain parts of the world, the average multiplex signal power must be controlled to reduce adjacent channel
interference. The currently enforced standard falls under the ITU BS-412 regulations. The Omnia.11 FM has a very
effective Multiplex Power Limiter that may be enabled to comply with these regulations.
Loudness Loss Warning!
If your country's regulatory agency does not require the use of the ITU BS-412 Multiplex Power Limiter, make
certain that the BS-412 “Engage” control is set to “Off”, or severe loss of loudness will result! For example, when
the ITU BS-412 Power Limiter is switched on and set at 0.0dB, there is approximately a FIVE dB loudness loss over
the limiter being switched off!
BS-412 Engage: This control enables (On) or disables (Off) the BS-412 Power Limiter. The default setting is Off.
Threshold: When On above, this control sets the average multiplex power from -3.0dB up to 9.0dB (in 0.25dB
steps) with respect to the original 0.0dB ITU BS-412 standard.
There is also a BS-412 Drive control located in the FM menu that is activated when this feature is engaged. This
adjusts the depth of limiting.