Listen Technologies LT-82LA, LR-42, LR-44, LA-351 Key Concepts of Designing a Stationary IR System

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System Overview

Key Concepts of Designing a Stationary IR System

1Each LT-82 transmitter used can power two LA-140 radiators

Each LT-82 transmitter used can power up to two LA-140 radiators. If you design a system that requires more radiators than the transmitters can power, you need to order additional LA-205 power supplies. Each LA-205 can power up to two LA-140 Radiators.

2Up to four LT-82 transmitters can be interconnected to create up to a four channel system

Up to four LT-82 transmitters can be interconnected to create up to a four channel system. For the system, there are two RF outputs provided for connection to the radiators. Each of these two outputs is referred to as the “Radiator Daisy Chain.” RG-58 coaxial cable is used to interconnect the RF in the radiator daisy chain. You can connect as many radiators in the daisy chain as you need.

NOTE: Adding additional transmitters will decrease radiator coverage.

3Each radiator requires one RF (RG-58 coax) connection and one power (CAT-5) connection

Each radiator requires one RF (RG-58 coax) connection and one power (CAT-5) connection. The RF connection can come from a transmitter or from another radiator. The power connection can come from

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4Listen has provided mounting hardware for most LA-140 mounting situations

To make it easy for you to design, specify and install a system, Listen has provided mounting hardware for most mounting situations including wall, ceiling, corner, desk, tripod and mic stands. To double the radiation power you can vertically or horizontally mount two radiators together using the LA-342 dual radiator mounting brackets. This includes coaxial RF and CAT-5 power cables.

5It is possible that the RF signal arrives to different radiators at different times

Due to the higher modulation frequencies, it is possible that the RF signal arrives to different radiators at different times. This delay can cause the IR carriers to add “out of phase” and cause the signal to drop out. To solve this problem, Listen has provided a delay compensation adjustment on each radiator.

This design guide will help you calculate the setting for this adjustment.

6As the number of channels increases, the effective radiated coverage declines

As the number of channels increases, the effective radiated coverage declines. For example, a two channel system will have half the coverage of a single channel system. If is important to increase the number of radiators for multiple channel systems.

7The coverage patterns provide coverage of the system assuming no reflection

7KHFRYHUDJHSDWWHUQVSURYLGHGE\/LVWHQSURYLGHFRYHUDJHRIWKHV\VWHPDVVXPLQJQRUHÁHFWLRQ,Q addition, the radiator has been under-rated to account for system degradation as the IR emitting LEDs age over time. It is important to design the system based on these coverage patterns and not by trial and error. The reason for this is that the coverage pattern will be stronger when the radiator is new.

A system that has adequate coverage today may not have adequate coverage in the future if not

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8The maximum length of CAT-5 power cable

CAT-5 power cable should never exceed 1000 feet from the source power supply.

9The maximum length of coaxial RF cable

Coaxial RF signal cable should never exceed 1000 feet from the source transmitter.

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