[TowerTalk] HFTA first impressions

[George Fremin III]

On Sun, Nov 09, 2003 at 05:22:48PM -0800, Jim Lux wrote:
> 
> 2) The instructions on getting DEM data are mindbendingly complex and
> confusing, especially with respect to properly installing it in the right
> directories, etc.  The microDEM program is quite slick (probably too
> powerful for this application, by the way), but all that capability means it
> takes a lot of configuring.  A program like RadioMobile does this MUCH
> better.
> 
> 3) The instructions given for creating the terrain profile files do not
> work.  The version of MicroDEM on the CDROM doesn't save the profiles
> created in the viewshed analysis. It doesn't allow you to click the "save
> radials" option, which is grayed out.  The HFTA pdf file tells you that you
> can enter the lat/lon for the viewpoint once you have clicked on the DEM
> data, but in reality, it's where the cursor is when you (double) click that
> determines the viewpoint.


Yes - using MicroDEM to get the terrain data is a bit hard.
But the method I used before this program is MUCH more 
time cosuming and trouble - drawing lines on USGS maps
and reading off the elevations makes you really appricate 
how much faster and easier it is to use MicorDEM.


> 4) It would have been much better if they had simply provided a single
> program that you enter the lat/lon of the station, how many radials, how
> far, what post spacing, etc. in a dialog, and it would spit out the required
> text files.  Sure, it's cool to use a sophisticated mapping program, but
> there's a lot more that can go wrong.

That would be nice - do you know of such a program?  I think N6BV or 
someone else would have to write one.  Instead Dean provides instructions
to use MicroDEM to get the data - and I think he also still gives 
you the option of getting the elevation data off of a map.


> 5) There is no documentation about how HFTA works, in either the program
> documentation, or in the Antenna Book.  There's a general description in the
> book of the diffraction analysis, but no theory, and what's important, no
> place to go look for a better description.  The textbook cited on GTD is all
> well and good, but I wasn't looking forward to rederiving how HFTA might
> work from first principles.

Sounds like it would be a good idea - I think alot of this was
covered several years ago in a QEX article that N6BV wrote.



-- 
George Fremin III - K5TR
geoiii at kkn.net
http://www.kkn.net/~k5tr