SECTION 3
FUNCTIONS & FEATURES
3.1 FUNCTIONS
The MK-7 Buddy-Line hard-wire system utilizes the “four-wire” approach. 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 ComRope (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 Interspiro Divator MKII “AGA” full-face mask (FFM) is what
most professionals prefer, according to our statistics. A hard-wire system requires
a physical connection (i.e., umbilical/ComRope) between the listener and talker.
The signal travels over the communication ComRope.
Most hard-wire intercoms can be congured for either two- or four-wire operations.
Four-wire communications is dened as a duplex communication route. Two wires
provide the uplink signal path, and two additional wires provide the downlink path.
Thus everyone can be online simultaneously (similarly to a telephone conference
call). Since the diver is never cut off the diver while talking, as is the case with
a two-wire system, the four-wire system is the safer of the two congurations.
Due to the increased efciency achieved with a four-wire system (duplex) and its
simplicity of use, the MK-7 is designed for four-wire operation only.
The standard MK-7 conguration 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 amplied by the upper
electronics module and routed through the ComRope. Connected to the ComRope at
the diver’s end is the earphone-microphone assembly (typically an EM-OTS-2 for
the new Guardian FFM or EMA-2 for the Interspiro FFM). The tender’s speech is
reproduced by the earphone part of the assembly. 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 ComRope, received by the upper electronic module, amplied,
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 electronics module.
- IMPORTANT SAFETY NOTES -
It is extremely important that the divers are dressed out in a manner that will
strain-relieve the ComRope. Commercial dive schools typically instruct students
to have the ComRope tethered to the diver’s harness or buoyancy compensator
with a quick release. If someone pulls on the ComRope and the diver loses control
of the ComRope, the pull is on the harness, not on the diver’s mask. This setup
prevents accidental removal of the diver’s mask.
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