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[aprssig] The best resolution of position from APRS

Curt, WE7U archer at eskimo.com
Tue Jan 3 15:19:25 UTC 2006


On Tue, 3 Jan 2006, J. Lance Cotton wrote:

> The best resolution is to use compressed mode. Unfortunately, several
> months ago, Bob said that no one should use it at all, lest the be
> tempted to use it on an Object or Item which wouldn't be decoded by the
> Kenwoods.

True.  Xastir supports compressed positions and compressed
objects/items.  I encourage people to flip on compressed mode for
those types in Xastir for search and rescue work due to the
increased resolution.  Might be useful for events as well, as
otherwise you only get something like 60' resolution for placing
objects on your map.  Depending on the type of event, that may or
may not be enough.


> If we all used compressed position packets (on all but items and
> objects), all of our packets would be so much shorter and the 144.39
> channel could support more users (or rather could better support the
> existing ones!)

I run nothing but compressed packets from my home station.  If
someone wants to see what they look like, look for packets from
we7u-3.


> And we'd get the advantage of increased numerical precision, if not
> accuracy (depends on the GPS).

Objects/items are usually placed via a mouse on a desktop client, so
GPS accuracy has little to do with them.  For mobiles though, it
helps to eliminate the regular 60' grid of points that mobiles can
occupy, easily seen at close-in zoom levels for parked mobiles
who've left their tracker on.

--
Curt, WE7U.   APRS Client Comparisons: http://www.eskimo.com/~archer
"Lotto:    A tax on people who are bad at math." -- unknown
"Windows:  Microsoft's tax on computer illiterates." -- WE7U
"The world DOES revolve around me:  I picked the coordinate system!"




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