Listen Technologies Stationary LA-350 - Manual (Page 14)

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Design GuideDesign Guide Design Guide
System Overview
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.
Key Concepts of Designing a Stationary IR System
1
Each LT-82 transmitter used can power two LA-140 radiators
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.
2
Up to four LT-82 transmitters can be interconnected to create up to a four channel system
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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3
Each radiator requires one RF (RG-58 coax) connection and one power (CAT-5) connection
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.
4
Listen has provided mounting hardware for most LA-140 mounting situations
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.
5
It is possible that the RF signal arrives to different radiators at different times
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.
6
As the number of channels increases, the effective radiated coverage declines
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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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The coverage patterns provide coverage of the system assuming no reflection
CAT-5 power cable should never exceed 1000 feet from the source power supply.
8
The maximum length of CAT-5 power cable
NOTE: Adding additional transmitters will decrease radiator coverage.
Coaxial RF signal cable should never exceed 1000 feet from the source transmitter.
9
The maximum length of coaxial RF cable