T&T: New VHF

[Peter Bennett]

Saturday, October 11, 2008, 8:46:15 AM, Michael wrote:

ML> For the plotter to show the polled position, doesn't this mean that the VHF
ML> now becomes a 'talker' on the NMEA net?

Yes.

ML> If so, isn't only one talker allowed on the net?  In this case I'm assuming
ML> the plotter is already a talker [e.g., it's sending position and waypoint to
ML> the autopilot] and the net is NMEA 0183.

Yes.  You will need two separate NMEA-0183 circuits: the existing one,
where the plotter talks to the radio, autopilot and radar, and a
second one where the radio talks to the plotter.

ML> Also, doesn't the plotter have to have the discrete capability to display
ML> the NMEA sentence output by the VHF?

Yes, the plotter would have to understand the radio's message, and
know how to handle it.

ML> If there is a multiplexer in the net, then isn't that the only way that more
ML> than one talker can be accommodated?

A multiplexer is used when two or more talkers want to talk to the
same group of listeners.

ML> Is there a NMEA sentence associated only with the VHF output of polled unit
ML> position, course and speed?  If so, what is it?

There probably is, but I don't know what it is (yet).

Some DSC-capable radios do not have an NMEA-1083 output.  If you do a
position request, the response will just be shown on the radio's
display.

ML> Someone please straighten me out on this.
ML>  
ML> Mike Loy
ML> PACHIS
ML> 47' McKinna FB Sedan
ML> cell (843)514-6663

-
Peter Bennett, VE7CEI    Vancouver, B.C., Canada
Ennos 31 "Honeycomb"
GPS and NMEA info: http://vancouver-webpages.com/peter 
Vancouver Power Squadron: http://vancouver.powersquadron.ca