There is never any voice on 70, only data, at least in theory. DSC radios
won't let you do voice on 70. Dunno about older radios. For the emergency
button, 16 is working channel. For individual calls, the calling human sets the working
channel prior to the call. The radio does not check that the working channel is free.
It's normal analog voice comms on the working channel.


"Ted" wrote in message ink.net...

"Wayne.B" wrote in message ...
On Sat, 25 Feb 2006 02:23:31 GMT, "ted" wrote:

I'm not sure why they dont implement DSC on all VHF marine channels. Maybe
they will in the future after it is proven on channel 70.

You miss the point. Channel 70 is the calling channel for DSC, not
the working channel, just as channel 16 is the calling channel for
voice.


Perhaps I did miss something here. Are you saying that there is never any voice on channel 70, but only a digital data exchange
and then both ships radio's change freqency to a working channel? Who decides which working channel to switch to? Does the radio
check to make sure the channel is not in use first? I assume that the voice communication on the working channel is analog and can
be heard by traditional radio equipment?