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 TM 55-1905-242-14
0008 00
COMMUNICATION SYSTEMS
General
Several communication systems are installed on the LCM-8 Mod 2 that permit both internal, external, and emergency
communication. Internal communication, within the LCM-8 Mod 2, is accomplished with a loudhailer system. External
communication is accomplished with VHF/FM (very high frequency/frequency modulation) radios, SSB (single sideband)
radio, SINCGARS (single channel ground to air radio system) radio, navtex receiver, and by data transmission via modem.
Emergency communication is accomplished by the DSC radios, watch receiver, Emergency Position Indicating Radio Beacon
(EPIRB), Search and Rescue Transceiver (SART), and survival radio.
Internal Communication
Loudhailer
A Raytheon RAY 430 loudhailer system is installed on the LCM-8 Mod 2. The loudhailer receives 12 Vdc power from a
dedicated 24 Vdc to 12 Vdc transformer mounted under the pilothouse chart table. This system permits 2-way communication
between the pilothouse, the weather deck, and the accommodation module. The operator may broadcast to either the
weather deck or the accommodation module from the pilothouse station and may then choose to listen to those areas. No
provision is made for direct communication from the weather deck or the accommodation module back to the pilothouse.
External Communication
VHF/FM Radio
Pilothouse VHF/FM Radio
A Ross DSC 500 VHF/FM radio is installed in the pilothouse console and provides communication between the LCM-8
Mod 2, other vessels, and shore stations. The radio receives 12 Vdc power from a dedicated 24 Vdc to 12 Vdc transformer
mounted under the pilothouse chart table. VHF/FM is a "line-of-sight" communication method, and is, therefore, suitable
only for short range communication.
The Digital Selective Calling (DSC) feature provides distress alerting and safety calling. With DSC, a distress call can be
placed by pressing a single key. This distress call will be received by all DSC-equipped vessels in range and will sound alarms
on each one. When interfaced with the GPS, the DSC feature can automatically broadcast the vessel's location along with the
distress call, making it easier for other vessels to render assistance.
In addition to its safety features, the DSC feature also permits scrambled communications between two or more DSC units.
Handheld VHF/FM Radio
Two Standard Horizon HX350S handheld VHF/FM radios are provided with the LCM-8 Mod 2. When not in use, the radios
are stored in charger/stands located in the comms rack in the accommodation module. While in their charger/stands, the
radios' batteries are recharged. The charger stands receive 110 Vac power from the power strip and the 220 Vac to 110 Vac
transformer mounted near the comms rack. The handheld VHF/FM radios do not have DSC capability.
SSB Radio
Two SEA 330 HF/SSB radios are installed on the LCM-8 Mod 2. One unit is installed in the pilothouse, and the other is
installed in the comms rack. The radios share a SEA 3301 controller mounted in the comms rack and an antenna coupler/
tuner mounted on the forward corner of the accommodation module top, starboard. The radios receive 24 Vdc power from
the vessel's 24 Vdc electrical system through the command & control distribution box.
A SEA 7000 MF/HF DSC controller and a SEA 7001 watch receiver are also included in the SSB radio system. The DSC
controller adds DSC capability to the SSB radio. The DSC features for the SSB radio are identical to those for the VHF/FM
radio. In addition to these features, however, the DSC controller for the SSB system can print its output to a serial printer
located on the comms rack. The watch receiver monitors all six SSB distress frequencies and alerts to any distress signals
received. The watch receiver makes it possible to monitor distress signals from non-DSC sources.
0008 00-3
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