[Towertalk] Terrain Analysis

[Ford Peterson]

Dink wrote:


> What I learned last week has taken me to a new
> area in my Amateur career. Terrain Analysis.
> Fascinating stuff.
>

SNIP...

>
> Am I working too hard at this? (I guess I could change the
> data to bigger steps and see if the graphs change.) My terrain
> has a lot of variation and I figured I couldn't be too
> detailed but does YT/YTAD really make use of that kind
> of detail? Does a range of intervals like I have selected
> mess up the calculations - should I stay fairly consistant
> instead?
>

Great minds think alike!  I've been investigating the very same topic for
the past week.

I found this software by VE2DBE...

http://www.cplus.org/rmw/english1.html

That is used to compute the HAAT and VHF/UHF coverage of mobile stations.
The nifty thing is, it uses the USGS topomap data available on the internet.

The data file contains the height above sea level in meters.  The cool thing
is that the USGS uses a radar mapping scheme that took a plot of every grid
everywhere.  The grid is 10 meters on a side.  Yes, every 10 meters.  You
can program the topographical profile granularity down to 1 meter resolution
if you like.  A map of your QTH, centered on your tower (GPS coodinates) and
you can figure your topomap for the terrain analysis.

I sent an email to the author a few days ago to see if the process could be
automated for various points on the compass, no response.

The maps are real nifty.  If you set the granularity to be small, you get a
map with color contours that change each time the altitude changes.

No, I don't have it all figured out yet, but the maps are cool.

If you figure a better way to grab the data, let me know.  I'm interested
too.

Ford-N0FP
ford@cmgate.com