Listen Technologies Stationary LA-350 - Manual (Page 11)

5
Design Guide Design Guide
Infrared Technology Overview
Infrared or “IR” technology uses infrared light to transmit audio without wires. This type of transmission is
advantageous to RF transmission because it is secure, it is not susceptible to RF interference, and one receiver
can be used for multiple rooms within a facility. The transmitter accepts an audio signal and then frequency
modulates an RF carrier at 2.3, 2.8, 3.3 and/or 3.8MHz. This carrier along with DC power (to power the
radiator) is supplied to the radiator via cables. The carriers are then radiated into the room using IR emitter
diodes. This is the same technology used by the remote control of your TV set. A receiver then receives the IR
light and demodulates the carrier.
1 2 3 4
Audio Source
IR Transmitter
Radiator
Receiver
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a facility so users will not have drop outs of the IR signal. This design guide will help you do this.
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achieve greater coverage. For example, when emitting in a very large room (like an exhibit hall) you will
notice that you need to point the receiver directly at the radiator to pick up the signal. However, when
the radiator is placed in a smaller room (for example 50 ft 2 /14.6 m 2 square) with white walls you will
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directions, increasing coverage.
• Listen systems use higher modulation frequencies that make the system less susceptible to light
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interference from sources that create IR light such as sunlight and plasma displays.
• Listen products are compatible with other manufacturers who use the same modulation frequencies
(2.3, 2.8, 3.3, 3.8 MHz).