AST Digital Magazine June 2017 Digital-June | Page 7

Volume 13
Speaker locations are determined to ensure 100
percent emergency alert coverage with maxi-
mum intelligibility.
For the hearing impaired, visual lights and mes-
sage boards are used.
The acoustics of an indoor space is also affected
by the acoustical absorption of its boundaries,
and if the walls, floor and ceiling are covered by
absorptive or non-absorptive finishes.
June 2017 Edition
by ATI Systems use a central Communications
Control Unit (CCU), which has been designed to
ensure that all speakers are in perfect synchro-
nization.
In the case of indoor systems, the CCU is con-
nected to an ISU which controls and powers the
actual speakers.
In many cases, one will find non-absorptive fin-
ishes which will reflect sound off their surface,
creating additional considerations for echo and
reverberation.
By examining the individual contributions and re-
flections from each speaker location, multiple ar-
rival effects and shadow regions can be identified
to assist with speaker orientation and placement
in order to achieve optimal intelligibility and cov-
erage.
For indoor applications, ATI developed the Indoor
Speaker Unit (ISU) that is well designed for ex-
cellent acoustic characteristics and can reach the
design goals.
Indoor MNS Using the ISU to Maximize
Intelligibility
An important consideration for the intelligibil-
ity of messages delivered by any system that
uses multiple speakers is the perfect coordi-
nation of those devices.
If the speakers delivering the message are not in
complete synchronization, then different parts of
the message may arrive at listener’s locations at
different times, making it much more difficult to
understand.
This is particularly important for indoor systems,
which often include greater numbers of speak-
ers, installed closer together.
Warning and public address systems designed
ISU with cabinet door open to show electronics inside
The ISU provides up to 400 Watts of continuous
audio output power for reliable alert tone notifica-
tion, voice instructions and public address, and
can also be configured to provide activation of
visual alerting devices such as strobes and mes-
sage signs.
The ISU is monitored, controlled and activated
by the ATI Central Control Station, and can also
be optionally configured as a standalone voice
evacuation system to operate independently us-
ing a local control panel.
It utilizes a high efficiency Class-D amplifier, the
unit puts out 400 watts of power with 4 zoned,
Class-B supervised, 70V Speaker outputs to de-
liver the highest level of voice intelligibility.
The ISU uses a 24VDC NAC power supply to
drive the 4 Zoned, Class-B supervised outputs
up to 10 Amps It features the computing power