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[aprssig] FCC's Calculation of HAAT

Chris Rose kb8uih at sbcglobal.net
Wed Dec 15 23:35:54 UTC 2004


Thanks Eric.

Chris 
KB8UIH

--- "Eric H. Christensen" <kf4otn at earthlink.net>
wrote:

> § 24.53 Calculation of height above average terrain
> (HAAT).
> (a) HAAT is determined by subtracting average
> terrain elevation from
> antenna height above mean sea level.
> (b) Average terrain elevation shall be calculated
> using elevation
> data from a 30 arc second or better Digital
> Elevation
> Models (DEMs). DEM data is available from United
> States Geological
> Survey (USGS). The data file shall be identified. If
> 30 arc second
> data is used, the elevation data must be processed
> for intermediate
> points using interpolation techniques; otherwise,
> the nearest point
> may be used. If DEM data is not available, elevation
> data from the
> Defense Mapping Agency’s Digital Chart of the World
> (DCW) may be
> used.
> (c) Radial average terrain elevation is calculated
> as the average of
> the elevation along a straight line path from
> 3 to 16 kilometers extending radially from the
> antenna site. At least
> 50 evenly spaced data points for each radial
> shall be used in the computation.
> (d) Average terrain elevation is the average of the
> eight radial
> average terrain elevations (for the eight cardinal
> radials).
> (e) The position location of the antenna site shall
> be determined to
> an accuracy of no less than ±5 meters in both the
> horizontal
> (latitude and longitude) and vertical (ground
> elevation) dimensions
> with respect to the National Geodetic Reference
> System.
> 
> 
> 73s,
> Eric KF4OTN
> kf4otn at amsat.org
> http://www.ericsatcom.net
> 
> Project OSCAR Member
> AMSAT-NA Member: 35360
> AMSAT Eastern North Carolina Area Coordinator
> 
> -----Original Message-----
> From: aprssig-bounces at lists.tapr.org
> [mailto:aprssig-bounces at lists.tapr.org] On Behalf Of
> Chris Rose
> Sent: Wednesday, December 15, 2004 17:56
> To: TAPR APRS Mailing List
> Subject: Re: [aprssig] bad PHG, or lots of big
> towers?
> 
> 
> I would still ask exactly what is average terrain?  
> 
> Is it the spot of ground the tower sits on or is it
> something else?
> 
> If a small mountain say 5k high sits in the middle
> of
> a plain somewhere, from where is the average terrain
> found?  
> 
> The base of the tower or the flat land at the base
> of
> the mountain?
> 
> Chris 
> KB8UIH
> 
> --- Steve Dimse <k4hg at tapr.org> wrote:
> 
> > On 12/14/04 at 9:38 AM Gerry Creager n5jxs
> <gerry.creager at tamu.edu>
> 
> > sent:
> > 
> > >Height Above Ground at the tower base.  So:
> What's
> > the Height Above
> > >Average Terrain?  That is, in my opinion, the
> > height that should be
> > >advertised.
> > >
> > Not just an opinion, the spec is very clear on the
> > fact that the H in PHG is
> > above average terrain...
> > 
> > Steve K4HG
> 
> 
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> 
> 
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