Hi Vytenis. Several things:
You need to use the arrival angle data at
http://www.arrl.org/notes/9876/, which are updated using the latest
version of VOACAP, which has some significant changes, particularly
at low angles. The YT data you used date from 2000.
Because of the size of the United States, a statistical file for
"LY-US" is necessarily going to involve compromises. I don't know
whether N6BV used the center of the USA for his VOACAP runs to
develop those tables, or if he somehow averaged statistics for
multiple USA areas.
1000 KM is a fairly significant distance between locations when
comparing propagation with a program such as VOACAP. I wish I could
hear some of the things that my friends in New England and Florida
hear on various HF bands at various times.
73, Pete N4ZR
At 05:52 AM 6/26/2009, Vytenis Sciucka wrote:
>I have found nice program HFTA on the ARRL Antenna book and relative
>article bu G3TXQ in the latest QST, May. I got an idea to make some
>calculations and evaluations of my QTH and antenna performance using
>this program and Enhanced Elevation-Statistical Files provided
>http://www.arrl.org/notes/antbook/yt-files.html Initially I assumed if
>I take yt files for locations closest to my QTH, data should be very
>similar to each other and I will be able to find numbers for me by
>extrapolation. But after I moved data from closest locations to me
>(OH, OK, SM and UA3 - <1000km) to Excel and draw it on the chart, I
>found elevation angles are bit different for each location. USA
>direction case you can find in
>Basically, I have two questions. Are these files somehow usefull for
>my LY location. And only if not, is there any way to modify,
>extrapolate or whatever to make them useful.
>Any idea how this data has been obtained?
>Thank you very much
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