2820A-02 & 2820A-03 CHAMBER COMMUNICATOR USER MANUAL
2820A-02-UM
REV 1.0
15
5.3
OPERATING ON AC POWER
The communicator is normally operated on AC power using the internal battery as backup in
case of power failures. The internal power supply is designed with medical grade electrical
isolation to prevent possible injuries due to electrical leakage. If external power is supplied
through the EXTERNAL POWER connection on the MS connector, it should have the same
type of isolation to prevent possible electrocution.
5.4
MODES OF OPERATION
The Models 2820A-02 & 2820A-03 have the ability to operate in either 2-Wire or Full Duplex
(4-Wire). Both the chamber and the operator can be connected in either mode and a
combination of modes can be used. If either the chamber or the operator is wired in 2-Wire
mode, the operator must use a push-to-talk, either the PUSH-TO-TALK SWITCH or PUSH-
TO-TALK JACK, when talking to the chamber. Using either push-to-talk method will cut off
the entertainment speaker.
2-Wire
communication is defined as a single communication path, normally the chamber is
the priority signal path – operator listens to chamber. Signal reversing is accomplished by
pushing the PUSH-TO-TALK SWITCH – chamber hears the operator. Since only one person
can talk at a time, there is a level of discipline that goes with using 2-Wire mode in order to
obtain clear communications. One advantage of 2-Wire is that the operator’s microphone is
not active unless one of the two push-to-talk controls, PUSH-TO-TALK SWITCH or PUSH-
TO-TALK JACK, are active. This eliminates any possible acoustic feedback between the
operator's microphone and the PANEL SPEAKER. It also prevents noise from the outside
reaching the chamber occupants and allows the operator to communicate with other crew
members without involving the chamber occupants.
4-Wire
(Full Duplex) communication is defined as a dual communication path, a signal path
(a pair of wires) for up-link and a signal path (a pair of wires) for down link. A common
example of Full Duplex communication is the telephone. Full Duplex (4-Wire) has the
advantage of natural communication without having to use the PUSH-TO-TALK SWITCH.
This keeps the operator's hands free to perform other task. It does not require the same level
of discipline to achieve clear communications that 2-Wire does. It has the advantage that
neither the chamber occupants nor the operator are cut off when the other is talking. 4-Wire
does require the chamber occupant, as well as the operator, to wear headsets.
5.5
SETTING THE VOLUME CONTROLS
5.5.1
2-WIRE MODE
Turn power switch to ON, turn speaker switch to ON, and adjust all volume controls
to mid-scale. The operator has to depress PUSH-TO-TALK BUTTON in order to
the chamber occupants. Operator and chamber occupants talk to each other while
the operator adjusts volume controls. Adjusting the lock volumes is easier if the
other LOCK ON/OFF switch is turned off.
OPERATOR VOLUME
– While chamber occupant(s) are talking, the operator
adjusts this volume control to a comfortable hearing level at the PANEL SPEAKER
or operator headset.
Summary of Contents for 2820A-02
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