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Jambo Jump Page 3

Electronics - September 2002 - Electronic Q&A
Electronics September 2002
By Ben Ellison


Jambo Jump
Electronics Q & A
   
 
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I recently installed a VHF radio with DSC. Now how do I test it? S.M., via e-mail
Unfortunately, testing that red button which is supposed to send an automated distress signal simply can't be done. In fact, doing so could constitute a crime. However, you can check out other DSC aspects of your new radio and thus be fairly confident that the distress function will work if ever needed.

For starters, be sure that your radio is getting proper position data through its NMEA connection to your GPS. This should be fairly obvious, though it varies from manufacturer to manufacturer. If you have a Standard Horizon or Simrad unit--and, of course, your GPS is powered up and locked in--the radio should show your present latitude and longitude on its screen (see photo). A Raymarine DSC radio will beep at you on startup if it is not getting valid position data and display "NMEA" when the data is good. Icom has a similar screen indicator, only it reads "GPS."

You might also check that your MMSI (Maritime Mobile Service Identity) number is properly programmed into the radio. Most units have a way to display it on screen, which is usually explained in the manual. If you haven't actually gotten a number yet and yours is a recreational vessel that stays in U.S. waters, you can get a free MMSI from BoatUS, Maritel, or Sea Tow. Otherwise, you'll need an FCC ship's license. Be careful entering the number into your set, as some only allow one try without dealer assistance.

Finally, you should call someone using DSC. This can be harder than it sounds, as nondistress DSC calls are directed to one or more specific MMSIs and most of us are not yet trading them as we do cell numbers. That day will come, but in the meantime, many commercial yacht towers are DSC-equipped and willing to give you their MMSI over a voice channel and then participate in a radio check. (After all, this technology can really simplify their work.)

All passenger-carrying vessels and ships now monitor DSC and may be willing to help, and the Web site www.boatered.com is compiling a database of agreeable DSC-enabled boaters. One way or another--and you may end up pounding the docks--you should be able to find someone within VHF range willing to work DSC with you. Then you'll need to consult your manual for the details of initiating a one-to-one digital call on a working frequency like 68. Once you're communicating, try the nondistress position-requesting and receiving functions most of these sets have.

During this process, you will no doubt notice that the VHF manuals have gotten thicker and the screen menus more complicated. An old-fashioned radio check on channel 16 was a relative snap (and is still worth doing). However, if your DSC testing goes well, the chances are excellent that if you ever have to lift that guard shield and hold down the distress button the required five or so seconds, your radio will beep every other DSC-equipped party in the area with your location and MMSI. Your radio will keep sending the call until it is digitally acknowledged, and all the sets will also switch to 16 for voice communications. While the U.S. Coast Guard won't be fully monitoring DSC VHF for a few more years, it's more likely every day that someone will relay the message to them; then they can consult the master MMSI database for your full contact and boat data and initiate rescue operations fully equipped with information.      --B.E.

Got a marine electronics question? Write to Electronics Q&A, Power & Motoryacht, 260 Madison Ave., 8th Fl., New York, NY 10016. Fax: (917) 256-2282. E-mail: PMYElectronics@primediamags.com. No phone calls please.

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This article originally appeared in the January 2003 issue of Power & Motoryacht magazine.

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