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[aprssig] AVRS/APRS-Alert Updates

Lynn W. Deffenbaugh (Mr) ldeffenb at homeside.to
Fri Sep 30 21:15:03 UTC 2011


And I learned the hard way that reversing the bearing isn't a matter of 
swapping it 180 degrees.  That'll look close to right for some spots on 
the globe but be frantically off for other pairs of coordinates.  You 
have to reverse the arguments to your Haversine calculation (or whatever 
you're doing) to get the proper bearing relative to the other side.

Lynn (D) - KJ4ERJ - Author of APRSISCE for Windows Mobile and Win32

On 9/30/2011 4:56 PM, Keith VE7GDH wrote:
>
> I just tried this, but for the callsign I entered, it showed 68 km 
> south of
> Vancouver BC instead of 68 km north of Vancouver. Ah... km. Does it
> perhaps use km north of 49N and miles for sout of 49N? I'm south of 
> 49N, but most definitely in Canada.
>
> Another example... I entered the digi THYNNE and it returned information
> that it was 95.24 km WSW of Chilliwack. In fact, it is NE of Chilliwack
> by about that distance. It seems to be providing the reversed direction.
> Not a huge problem when someone knows the geography, but it could
> be confusing for a visitor.
>
> Try sending LOCATE VE7GDH to AVRS and it will return 18 km west
> of Duncan. I am most definitely east of Duncan.
>
> 73 es cul - Keith VE7GDH
> -- 
> "I may be lost, but I know exactly where I am!"
>
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