[aprssig] Position Ambituity in APRS!

William McKeehan mckeehan at mckeehan.homeip.net
Tue Jan 8 18:17:20 EST 2008

On Tue, January 8, 2008 6:01 pm, Robert Bruninga wrote:
>> please bear with me thru a few more questions...
>> So how do you define "approximately at 35N and 83W"? Seems to
>> me that's a well defined area as described by my box.
> No, it is preferred to be a circle of the right ambiguity size
> centered on approximately 35N and 83W.  The word "approximately"
> is because it should be randomized there.  Probably within say
> half or less of the radius of ambiguity...

If you eliminate the "randomized" portion, where would you plot a station that
gave you 35N and 83W as it's position? 3400.00N and 08300.00W ?

>> So if my APRS packet says 35  .  N\083  .  W,
>> I could actually be at 3467.85N\08272.45W ?
> Unfortunately, neither of those is a valid posit.  Minutes can
> only be 00 to 59.  But assuming you meant 3457.85N\08253.45W,
> then yes, the coordinates of  35N and 83W are closest to that
> position.

Yes, I was thinking in base 100, not 60 when I made up those numbers.

[big snip]

William McKeehan

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