Northern Airborne Technology AA83-100 - Manual (Page 7)

SM10 Rev. 4.10 AA31 ICS Mode Controller Manual
Section 1 Description
1.1 Introduction
This manual contains information on the AA31-001 and AA31-002 ICS Mode
Controllers. All derivative products will be covered by manual supplements, which can
be obtained from NAT as required.
Information in this section consists of purpose of equipment, features and specifications.
1.2 Purpose of Equipment
The AA31 ICS Mode Controller provides a convenient, centralized method of organizing
the aircraft audio system into multiple intercom circuits for independent or common
operation. This function is especially valuable for EMS and law enforcement
applications, where several independent operations occur within the aircraft that often
require isolation from each other, while retaining the ability to share common
communication.
The AA31 can provide ICS switching for three or four NAT Audio Controllers, or other
NAT products incorporating an ICS TIE LINE. The AA31 also has provisions for driving
external annunciators and interfacing for ICS Calling.
1.3 Features
Front panel annunciators provide positive indication of the ICS mode selection. The
LED on the right of the ICS Function Knob lights green to indicate ICS Function is ALL
COMMON. The LED on the left of the ICS Function Knob lights amber to indicate that
any of the ICS functions is in the ISO (isolated) position.
The AA31 has four annunciator outputs, one output for each ICS Function. The outputs
on the AA31-002 can drive the Isolated Warning inputs on a NAT Audio Controller. The
outputs on the AA31-001 and AA31-002 can drive external lamps.
The AA31 provides load matching so that the ICS Levels will not change as the ICS
Function is changed. When the AA31 isolates an Audio Controller’s ICS Tie Line, it
connects a resistor, equal to the load of the ICS Tie Line, in place of the isolated Audio
Controller.
The REAR CALL annunciators illuminate when a rear call signal is activated.
ICS Function switching is a passive circuit, so it will continue to operate with no power
to the AA31. The annunciators and outputs will fail without power.
Feb 4, 2005 Page 1-1
ENG-FORM: 800-0108.DOT
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