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[aprssig] PHG and HAAT

Stan Coleman [NØYXV] n0yxv at gihams.org
Fri Oct 14 20:34:10 UTC 2005

Ok I think I've finally figured out the difference. I thought we were talking
about APRS PHG and not FCC HAAT. Since this form is about APRS I just figured
we were talking about APRS. In APRS PHG land you can't and never would have to
enter a negitive number. Seams to me like half of the posters for this subject
have been talking about FCC HAAT and not APRS HAAT. I think Bob's right it's
not designed to be perfect because nothing would be perfect. PHG is only a
rough guess designed to let others know roughly what your range is.

As for using digi's that can hear me as an indicator of PHG (or range) would be
bad in my area as we have a couple of really tall digis in Western Iowa (and
Omaha NE) that can hear me here in Central Nebraska. While there are several
digi's in Nebraska that I simply skip over. Wouldn't work to draw a circle
around my tower large enough to cover Iowa as those are tall enough to hear me
although closer stations can' t. It would also make the back side of my circle
look really out of wack.

Quoting "Curt, WE7U" <archer at eskimo.com>:

> 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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