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[aprssig] whatever happened to....

Scott Miller scott at opentrac.org
Tue Aug 21 18:43:12 UTC 2007


gerheim at cox.net wrote:
> Doesn't increasing the ambiguity just round off the position data?  Then it would tend to jam all the stations into the same corner of the ambiguity rectangle.  (OK - or the _center_ of the ambiguity rectangle, depending on whether or not the data is truncated or rounded off.)  

Yes.  That's why I've never liked the scheme.  I'd much prefer a 
separate ambiguity magnitude indicator, so the client would know a 
center position and how 'fuzzy' to make it.

On a related subject, I'd really like to see some sort of flag that'd 
indicate a questionable position.  The T2 reports 'NO FIX' in the 
comment if there's no GPS fix (and that option is enabled), but it'd be 
nice to have a standard so that client software could still show a 
position but also indicate clearly that the station might NOT be there.

I think this is most critical for safety-related functions, like if 
you've got a bunch of storm chasers that you want to be sure are 
accounted for and not where they shouldn't be.  You need to first see 
that the position is current (within a defined time limit) and valid. 
If it's not valid, you still want the station to be able to report its 
last known position, since that's still useful information.

Scott
N1VG





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