In article ,
"Eisboch" wrote:

It would seem that the next logical evolution for VHF communications is for
it to go to a totally digital format, rather than the analog system it
remains. Digital will allow more available bandwidth for each frequency,
would open up the possibility of full duplex communications and would
provide clearer communications.

Digital would not necessarily be more efficient on bandwidth. And at the
end of the range, digital detoriates faster than analog.

Plus: The really important messages are already digital - a distress
call goes out in 5 seconds, including position (connect a GPS!) and your
identity (MMSI). In 10 seconds you manage to even detail what's wrong.
The radio will try until you get an acknowledge. And you get an
acknowledge rather quickly most of the time.

US lags somewhat behind Europe, but the USCG has a project Rescue 21
getting DSC going.

Read it all up under the keywords GMDSS, DSC, distress call.

Another very useful addition in VHF is AIS.

In order to reduce false distress calls, you have to pass either SRC
(short range certificate, VHF only) or LRC (long range certificate, VHF,
MF/HF) exams.

Hope this gives enogh pointers.

Marc

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