[aprssig] Position Ambituity in APRS!
Scott Miller
scott at opentrac.org
Tue Jan 8 12:21:24 EST 2008
For what it's worth, OpenTRAC has a positional ambiguity represented as
a 16-bit integer in meters - enough for a radius of up to 65 km. Though
in looking at the spec, I think it needs to be more clearly defined what
the 'estimated error radius' is.
One of these days I'll have time to work on it some more. I'm getting
there - as of yesterday, I'm no longer officially employed full time for
the first time since... well, since I got my first full-time job. Not
that it affects the number of hours I work each week, but now I get to
spend a few more of those hours on APRS and radio stuff!
Scott
N1VG
Steve Dimse wrote:
>
> On Jan 8, 2008, at 6:55 AM, Steve Dimse wrote:
>
>> For ambiguities that do not cross the poles or equator (the only case
>> allowed by the protocol), the border away from the equator is shorter
>> than border towards the equator, making it a trapezoid.
>
> To be correct, this statement should be
>
> For ambiguities that do not reach or cross the poles or cross the
> equator, the border away from the equator is shorter than border towards
> the equator, making it a trapezoid.
>
> Minor difference, but I think the protocol does allow ambiguity to reach
> (but not cross) the poles, and the linear projection of this would be a
> triangle.
>
> Steve K4HG
>
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