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[aprssig] SET 2009 APRS report

Dave Skolnick dskolnick at gmail.com
Mon Oct 5 12:43:44 UTC 2009


> APRS was active from 9AM to about 11AM.  During that time, in AA
> County, we observed 8 fixed stations, 7 mobiles, 3 boats and 4
> objects.  In addition, the APRS.FI site map overlayed the
> positions of several dozen Marine Mobile ships, boats and craft
> with VMS transponders giving an excellent virtual display of the
> tactical situation in the area.

Perhaps this is just a vocabulary issue, but what aprs.fi shows are
Automatic Identification System (AIS) transponders. See
http://www.navcen.uscg.gov/enav/ais/ . Interestingly (and relevant to
the WB4APR vision of APRS) is that the spiffier units allow the ship
operator to click on a target and transfer the MMSI (a unique
identifier) to a DSC marine VHF radio and directly contact that ship.
The operator has the name, destination, course and speed, and other
information from the AIS display (which often integrates radar and
chartplotter information). Accordingly the system provides both
greater situational awareness and supports communication. AIS is
installed on all ships greater than 300 tonnes and on towing vessels
by international agreement. A slightly derated version (completely
compatible) has recently become available for recreational craft so
you should see more AIS targets on aprs.fi in coming months.

VMS to me means Vessel Monitoring System that provides similar
location services on a less frequent basis using cellular and Iridium
links (depending on distance offshore). VMS is mostly used by fishing
fleets.

> My briefcase APRS GO
> kit should contain an AC power 1-to-3 adapter so I can plug into
> already full outlets.

Someone (Belkin?) makes a reasonably priced 1-to-3 that has a swivel
on the plug (making fitting into the host outlet easier) AND has two
USB ports for charging anything that runs on 5V and has a compatible
charging cable (bluetooth headsets, phones, iPods, etc). I have one at
the charging station in my boat and in my sailing go-bag.

> APRS display of Marine Traffic in the Chesapeake Bay and
> surrounding waters was a bonus that should be part of the
> Marine Band operating position.

Have you reached out to MD DNR and the Annapolis Harbormaster to
extend emergency operations and exercises to those agencies? I can
arrange an introduction to Ric Dahlgren if you don't know him already.

73 es sail fast, dave KO4MI
S/V Auspicious WDC9882



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