SECTION 3
FUNCTIONS & FEATURES:
3.1 Functions:
The MK-7 BUDDY-LINE
®
hard-wire system utilizes the “four wire” ap-
proach. It is a closed loop comparable to a telephone system. A typical
hard-wire system consists of a surface intercom, a headset with a boom
microphone, a Com-Rope
®
(set up for four wires, shielded or true spiral
four), a diver microphone/earphone assembly, a mask microphone, and some
sort of diving mask with accommodations for a microphone. The MKII-G
AGA full-face mask is what most professionals prefer, according to our
statistics. A hard-wire system requires a physical connection (i.e., umbili-
cal/Com-Rope
®
) between the listener and talker. The signal travels over the
communication Com-Rope
®
.
Most hard-wire intercoms can be configured for either two- or four-wire
operations. Four-wire communications is defined as a duplex communica-
tion route. Two wires provide the uplink signal path, and two additional
wires provide the downlink path. This allows everyone to be online simul-
taneously (similar to a telephone conference call). Since you never cut off
the diver while talking, as is the case with a two-wire system, the four-wire
system provides the safer approach of the two configurations. Due to the
increased efficiency achieved with a four-wire system (duplex) and its sim-
plicity of use, the MK-7 is designed for four-wire operation only.
The standard MK-7 configuration functions as follows: After the system is
powered up and all connections are properly made, the tender’s speech is
picked up by the boom microphone located on the headset. The voice is
amplified by the upper electronic module and routed through the Com-
Rope
®
. Connected to the Com-Rope
®
at the diver’s end is the earphone/
microphone assembly (typically an EMA-2). The tender’s speech is repro-
duced by the earphone part of the EM cable. When the diver speaks, his
voice is picked up by the mask microphone located inside the mask being
used. The voice is routed through the Com-Rope
®
, received by the upper
electronic module, amplified, and then routed to the tender’s headset. If a
second diver is on-line he will hear and talk as well in the same manner.
The volume of the tender and diver(s) is controlled by separate volume
controls on the outside of the upper electronic module.
3
