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[aprssig] PHG and HAAT

Curt, WE7U archer at eskimo.com
Fri Oct 14 20:08:13 UTC 2005

On Fri, 14 Oct 2005, Stan Coleman [NØYXV] wrote:

> Ops sorry still can't figure out how you can get a negitive number. According to
> how to figure HAAT in previous posts you couldn't get lower than a zero. Maybe
> figuring HAAT is so simple I'm missing something. Would seem to me if you have
> to go up 450'in either direction you would need a 460' tower to have a HAAT of
> 10'. Since, and I'm assuming, you don't have a 460' tower the HAAT would simply
> be zero. Don't know how you could represent a negitive number in either PHG or
> any other scale you could invent.

HAAT stands for Height Above Average Terrain.  Mine is negative
450ft due to living at the bottom of a bowl with hills/mountains
extending out in all directions from me.  Why can't you have a
negative height above average terrain?  Makes sense to me.

Whether I can represent negative HAAT in PHG is beside the point:
PHG was invented by Bob for APRSdos and put into the APRS spec.  He
probably had no need to account for negative HAAT in PHG, as
anything below zero equates to zero for APRS purposes.  That would
suggest to everyone that they not try to use me for a digipeater, a
generally good idea.

Curt, WE7U.   APRS Client Comparisons: http://www.eskimo.com/~archer
"Lotto:    A tax on people who are bad at math." -- unknown
"Windows:  Microsoft's tax on computer illiterates." -- WE7U
"The world DOES revolve around me:  I picked the coordinate system!"

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