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[aprssig] PHG and HAAT, more.

Gerry Creager N5JXS gerry.creager at tamu.edu
Fri Oct 14 14:46:54 UTC 2005


Topo data, in fact, street level data, are somewhat difficult outside 
the US.

I'm working on getting a new SRTM dataset in house.  If I can get that 
in, and working properly, I'll go ahead and add a web-mapping interface 
to allow looking at topo data and if I'm REALLY given enough time, maybe 
a real HAAT calculator with display based on web-mapping.

QUESTION:  Do we have anyone interested in learning Mapserver (open 
source web mapping tool) who'd be interested in doing this in THEIR 
spare time since most of my spare time is heading into work or D-STAR 
experimentation?  I can provide Mapserver hosting, and some help on the 
interface specs, if there's a taker:  Off-line responses, only please.

I think something like an international HAAT calculator would be very cool.

73, gerry

Dave Baxter wrote:
> Re:-
> 
> -*Snip*-
> 
>>>HAAT by the FCC definition (and I am quoting from memory and might
> 
> have parts of this wrong) are that you draw 36 radials out at 10 degree
> intervals from your location.  You then take 50 evenly spaced elevation
> data readings between 3 and 16 km along each of the lines.  These get
> averaged and a number is derived.  I have many locations along these
> radials from my house that are four to five hundred feet above my
> elevation when I trace out the lines to 16 km away.  This is how you get
> a negative number.  The Height is above the average terrain around you
> in a 16 km radius.  This is why it gets difficult to just guess at the
> number by looking around you in a hilly area.  In your transmitter is
> located in a deep valley you will most likely have a negative number for
> your HAAT.
> -*End Snip*-
> 
> Thanks for that..  (Wow.. km's too!)
> 
> Seems to me, that it's totally useless in parts of the world, such as
> Wales, Scotland, Switzerland and other "non flattish" places such as
> parts of California and other similar areas, even within the USA...
> 
> It also needs people to be able to read and understand a map (even have
> one in their possession that shows height data) something that is
> becoming very rare in these days of web based mapping, sadly.  Anyone
> know of a web based mapping system that shows the terrain height at the
> cursor, outside of the USA?..
> 
> If you have Memory Map, or a similar system loaded, you can draw the 36
> radials, and read the height out along the "paths" the system thinks
> they are.
> 
> More flames I suspect...  (Oooo. I just love stirring these things up!
> But it get's people thinking again.)
> 
> Dave G0WBX.
> 
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-- 
Gerry Creager -- gerry.creager at tamu.edu
Texas Mesonet -- AATLT, Texas A&M University	
Cell: 979.229.5301 Office: 979.458.4020 FAX: 979.847.8578
Page: 979.228.0173
Office: 903A Eller Bldg, TAMU, College Station, TX 77843




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