[TowerTalk] HFTA Accuracy / Usefulness

[Pete Smith]

Jim's making sense too - I always use 1-meter data from the USGS seamless 
database, so it makes no sense to enter fractional meters or feet in the 
terrain profile.

73, Pete

At 02:30 PM 3/20/2009, Jim Brown wrote:
>On Fri, 20 Mar 2009 11:29:29 -0400, Scott McClements wrote:
>
> >pecifically, would a 3D trace over a wider angle produce better
> >results?
>
>As an EE, I learned long ago that I will learn far more from
>finding many points on any curve than only one or two. It's far
>easier to understand the elephant with observations through many
>widely spaced pinholes. I ran HFTA over every 5 degrees of
>azimuth. Although my terrain is rather complex, I did NOT see the
>sort of inconsistency that Steve (N2IC) described.
>
> >Why is it just 2D?
>
>One very good reason is the level of detail in the avaiable
>terrain data, and how that relates to the wavelengths involved.
>Another equally good one is the nature and complexity of the math.
>It makes no sense to use a more complex calculation if the
>underlying data has less detail than the calculation. HFTA models
>the interaction of horizontally polarized waves with the earth,
>especially diffraction.
>
>I work in pro audio, where we must do a lot of work to understand
>how sound waves interact with enclosed spaces (like concert halls,
>theaters, etc), and I have done a LOT ofr complex FFT analysis of
>that sort of thing. N6BV's recent post in this thread makes
>perfect sense to me.
>
>73,
>
>Jim Brown K9YC
>
>
>
>
>
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