2825R TWO DIVER RACK MOUNT COMMUNICATOR USER MANUAL
2825R-UM
REV 3.0
17
fall rapidly. It is a good idea to leave the unit on for five minutes before relying upon
the battery condition indicator.
5.4
Modes Of Operation
The 2825R has the ability to operate in either 2-Wire or Full Duplex (4-Wire). Both the diver
and tender can be connected in either mode and a combination of modes can be used. If
either the diver or the tender is wired in 2-Wire mode, the tender must use a push-to-talk,
either the PUSH-TO-TALK ALL SWITCH or PUSH-TO-TALK JACK, when talking to the diver.
2-Wire communication is defined as a single communication path, normally the diver is the
priority signal path
– tender listens to diver. Signal reversing is accomplished by pushing the
PUSH-TO-TALK BUTTON
– diver hears tender. Often times a 4-conductor communication
cable is used with two wires tied together as a pair for redundancy, this is still a 2-Wire
system. 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 communication. One advantage of 2-Wire is that
the tender's microphone is not active unless one of the two push-to-talk controls, PUSH-TO-
TALK BUTTON or PUSH-TO-TALK JACK, are active. This eliminates any possible acoustic
feedback between the tender's microphone and the PANEL SPEAKER. It also prevents noise
from the surface reaching the diver and allows the tender to communicate with other
members of the surface crew without involving the diver.
Full Duplex (4-Wire) 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 BUTTON.
This keeps the tender'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 diver nor the tender are cut off when the other is talking. Because the diver's
microphone is not connected in parallel with the earphone, the diver is louder and potentially
clearer in Full Duplex (4-Wire) mode. More information on this mode can be found in Section
7, FULL DUPLEX (4-WIRE) - WHAT, WHY AND HOW.
5.4.1
2-Wire Operation
To connect the diver in 2-Wire mode, connect the communication umbilical wires to
the DIVER MICROPHONE binding post jack on the 2825R as shown in the wiring
drawing in section 4.9. If the umbilical uses a banana plug, simply insert the plug
into the binding post jack. Verify that it is firmly and completely seated. This may
require that the external plastic nut be tightened down. If the umbilical uses bare
wires, loosen the external plastic nut of the binding post jack. Either insert the bare
end of the wire into the hole in the metal shaft of the binding post or firmly wrap the
wire around the shaft. Tighten the nut until the bare wire is firmly fastened by the
nut. The nut should not be fastened on the insulation of the wire nor should any of
the bare wires touch.
The earphone connection is not used by the divers. The earphone jacks can be
used to operate a remote speaker. Both diver and tender conversations will be
heard.