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[aprssig] What is this big box?

Bob Bruninga bruninga at usna.edu
Sun Sep 30 23:25:29 UTC 2007


>> Noticed [Bob's car in a box] on my display this afternoon:
>> What does it mean?
http://picasaweb.google.com/joseph.durnal/General/photo#5116094600815595186

> He's got position ambiguity turned on, so the 
> box shows the entire square that could contain 
> his actual position.

Yes, that is my van, and my foot ripped out the GPS cable months ago.  Until I find time to make a new cable, I set my position about half way between work and home and set a 10 mile ambiguity.  So usually I am somewhere in the box which is my general sand box..

> Just don't ask if that's the appropriate 
> way to deal with ambiguity!

What he means by that is that position ambiguity is a religion...  it gets debated everytime someone brings it up. And now that you bring it up...

Actually, that is a nice display.  There is no mistake by anyone viewing it that it is "not normal".

My preference, however would be to make the following improvements to make it more in keeping with the original intent of position ambiguity...

1) Do not display the actual ICON, but display a big Question mark ICON instead, to further imply unknowns in the position.

2) Display the box as is is fine. But place that [?] icon and callsign randomly within the middle half of the square.

The reason for this is that there might be several people in the same box with ambiguity.  So you dont want them to all be on top of each other.  You want to visually grasp how many ambiguous positiosn are in the box at a glance.

A good example is Dayton.  You have a hundred or so APRS folks walking around the flea market with their D7's.  But it is a pain to carry a GPS and wires to actively report your position, and also it does not work indoors (half your time at the arena).

So you turn off the GPS, set your position to the middle of the HARA Arena, and set 0.1 mile ambiguity.  Now you will show in the immediate vicinty of the arena, your position will still transmit, but your position will not be absolutely wrong as it would be if you did it any other way.

Hope that helps.
Bob, Wb4APR




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