Feature 5 | COMMUNICATIONS SYSTEMS
the radio), as well as the nature of the distress if this is keyed in, at the press of a single button. It can also be used for safety and distress communications with selected parties. VHF channels are preset and operators
do not themselves tune to the frequencies. Thus marine VHF operation is very simple, requiring only the actuation of a microphone switch for transmit and a few front panel controls for on/off, channel selection, transmit power selection, squelch, volume, dual watch (the system simultaneously monitors Channel 16 and one other as selected) and scan. Radios, typically light and compact, can be fixed or portable. Many low-end sets are hand-held portables operating from an internal battery. Marine VHF equipment is inexpensive
and easily installed, but some knowledge of radio procedure and a licence are required to operate in transmit mode. The latest marine VHF generation incorporates DSC and eventually, once most vessels have DSC-capable equipment, it will no longer be necessary for crews to monitor Channel 16 constantly for distress traffic. There are numerous VHF sets on the
market, including examples from most of the big names in marine electronics. Standard Horizon, known for its value
products, is one such company. Standard Horizon’s fixed-mount GX3000E model has D-class DSC and incorporates an independent Channel 70 receiver to provide assured awareness of any digital distress/safety traffic. The smaller GX1500E model is suitable for small craft such as rigid inflatable boats (RIBs), sports boats and small workboats. In either case, a single distress button
initiates broadcast of a digital MAYDAY that includes the vessel’s identity, distress status, lat/long position and time. These radios have waterproof front panels and can therefore be used in vessels with open cockpits. The higher-specification GX3000E has
a larger display and can be provided with a telephone handset-type remote control or a smaller ‘fist mike’ with basic controls incorporated. Having either enables the system to be used as a dual-station radio and intercom. A backlit LCD provides clear indication of the channel selected complete with channel name and repeated GPS information. Other features of these 25W sets include one-button access to Channels 16 and 9, dual watch enabling Channel 16 to be monitored along with another selected channel, programmable scanning along with priority scan, plus NMEA inputs and outputs. A 2.25inch
(5.7cm) 4.5W speaker is audible in even the poorest conditions. A powerful 30W loud hailer is integrated, offering listen back, an automatic fog signal facility and other features. The DSC element can be used for privately polling and displaying another vessel’s position. Navico Group member Lowrance
similarly extends DSC capability, taking it still further with a feature that exploits position polling to present the positions of up to three ‘buddy’ vessels on a chart display. Users of its LVR-880 fixed-mount VHF can access this ‘track-your-buddy’ feature by connecting the DSC, via NMEA 2000 connectors, to a chart plotter equipped with Lowrance LCX, LMS or GlobalMap charts. The LVR-880 also has a built-in stereo FM radio receiver for normal broadcast reception. In
a significant technological
development, manufacturers of fixed-mount VHF equipment have started to integrate automatic identification system (AIS) receivers into their products. For example, ICOM offers AIS versions of its IC-M505 VHF/DSC and IC-M603 VHF/DSC marine transceivers.
Waterproof handhelds In terms of the ubiquitous hand-held VHF, Standard Horizon drew interest to its stand at the 2008 Southampton Boat Show by demonstrating the submersibility of its transceivers. The floating handheld HX-750E was
shown for the first time at the show. It is a compact fully waterproof unit that floats on its back if dropped in the water, facilitating retrieval. The HX750E is powered by a 1150mAh Li-Ion battery and can transmit at 0.5W, 1W or 6W. The usual marine and international
Inmarsat C console. 52
channels are present and the unit has a waterproofed socket for an optional external speaker microphone. A sizeable LCD provides clear wide-angle viewing while a large rotary dial allows users to change channels even while wearing gloves. This handheld is very compact, however, even smaller units available are the less powerful HX 270E, HX370E and HX500E, all of which are equally submersible and affordable. However, ICOM claims to have been first to offer a handheld that is waterproof
Ship & Boat International November/December 2008
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