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[aprssig] The best resolution of position from APRS

Wes Johnston aprs at kd4rdb.com
Wed Jan 4 02:56:17 UTC 2006


See http://www.kd4rdb.com/kd4rdb/k2jlb-7%20photo.jpg for a visualization
of the granularity of mic-e format.  I'm pretty sure the kenwood radios
will decode compressed positions from stations, but not for objects.

And just to be sure we (ie the masses on aprs sig) have terms right....
mic-e is not the same as compressed, although neither is human readable.

The thing I get a kick out of... is when MIC-e was developed, who
would've thunk that we'd have a GPS capable of 2m positons.  Kinda like
 Bill Gates saying "Who'll use all of 64k anyway?".

Wes

Curt, WE7U wrote:
> 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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