Linear Technology LINEARCOM3000 LC3.IRTX Operation Manual page 6

Carriers
System is transmitting within the 2 ~ 8 MHz frequency band. It can transmit up to 8 different
carrier signals (depending on the transmitter type) Carriers 0 to 5 are according to IEC
61603-7.
Aspects of infrared distribution
A good digital infrared language distribution system ensures that all delegates in a conference
venue receive the distributed signals without disturbance. This is achieved by using enough
and well positioned radiators, so that uniform IR signal with adequate strength can be
received at any place of the conference venue.
When planning an infrared distribution system several aspects influencing the uniformity and
quality of the infrared signal should be considered. These are discussed in the next sections.
Ambient lighting
IRRC08 can be operated without any problem even if fluorescent lamps (with or without
electronic ballast or dimming facility) such as TL lamps or energy saving lamps are switched
on.
For venues with large, unscreened windows, more radiators should be added. For outdoor
use, a site test will be required to determine the required amount of radiators. With sufficient
radiators, the receivers will work well, even in bright sunlight.
Objects, surfaces and reflections
Just like visible light, infrared radiation is reflected from hard surfaces and refracted by
hyaloid (glassy or transparent appearance) objects. Both objects in the conference venue
and structure of the walls and ceilings will influence the distribution of infrared light.
Infrared radiation is reflected from almost all hard surfaces. Smooth, bright or shiny surfaces
reflect well. Dark or rough surfaces absorb a large part of the infrared energy. Normally
surfaces opaque to visible light are also opaque to infrared radiation. Shadows from walls
and furniture will influence the transmission of infrared light. This can be solved by using a
sufficient quantity of radiators. They should be positioned in a manner to provide an infrared
field strong enough to cover the whole conference area. Take care not to direct radiators
towards uncovered windows, or most of this radiation will be lost.
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