Sound Off - Sail Magazine

Sound Off

Not everyone knows that you can use a Digital Selective Calling (DSC) VHF radio to call friends on other boats without using channel 16. It’s a great feature, particularly if channel 16 is very busy or if you want your call to be somewhat private. Here’s how it works. If I want to call a friend on Jubilee, I select a working channel—channel 72, for example—and check to see
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hr.sm.0207.SS.VHF1

Not everyone knows that you can use a Digital Selective Calling (DSC) VHF radio to call friends on other boats without using channel 16. It’s a great feature, particularly if channel 16 is very busy or if you want your call to be somewhat private. Here’s how it works.

If I want to call a friend on Jubilee, I select a working channel—channel 72, for example—and check to see whether it is free of radio traffic. If it is, I press the call/set key on the front panel of my radio to access its DSC menu; some DSC radios may have a different procedure, so check your instruction manual. I then scroll down the menu, highlight the individual option, and press the call/set key again to bring up a directory of boats I have entered into the unit’s memory. On my unit I program the individual letters and numbers into the unit using the call/set key and the channel-selector knob.

In addition to knowing the Marine Mobile Service Identity (MMSI) number of the receiving station before you can use this calling feature, you must also program your own MMSI number into your radio. Your MMSI number is listed on your boat’s FCC radio license. If you don’t have an FCC license, you can get an MMSI number from www.boatus.com or from www.seatow.com.

When your radio is properly programmed, using it to call someone is as easy as using a cell phone. In this case I select Jubilee from the list and press the call/set key to send a digital transmission that triggers a response on Jubilee‘s radio and identifies your boat as the hailing station. Although my radio remains dialed to channel 72, this hailing transmission occurs on channel 70.
The transmission sets off a loud ring tone on Jubilee, alerting them that my call is coming in. The ring tone is much easier to notice than a voice call on channel 16. Jubilee’s crew can accept my call by following the menu commands on their radio’s display panel. When they have done so, my unit will ring and will auto-switch to the preselected channel shown on the display. With both DSC radios now switched automatically to the preselected channel, we are free to talk.

If the other boat doesn’t respond to my call within 8 seconds, my radio will automatically send a follow-up transmission. If there is no answer to that call, it will display a “no response” message on its screen, and I can either keep trying or exit the menu.

It also works the other way. For example, if I miss an incoming DSC call, my unit will display an alert message on its screen telling me that a specific boat has called; obviously, my unit must be turned on for this to happen. If it is and I don’t answer, the call, including the time it was received, is also automatically logged in my radio’s “call waiting” directory.

Using the VHF without having to hail on channel 16 is a big advantage. DSC radios let you bypass the clutter and confusion. Niels R. Jensen

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