Someone on the list recently suggested using Google Earth as a means to
deriving topographic information for HFTA.
I have a related observation to put out to the group that appears to be
My QTH is located in a subdivision with strict antenna codes. However, I was
able to work an arrangement to lease land in an abandoned sand pit directly
behind my house, and I have located my towers on the leased land. It was a
perfect solution to a difficult problem. However, the sand pit is an ancient
river bed which was pushed up to become the top of a mountain by some long
ago geological upheaval and my actual QTH is located a few feet below what
remains of the top of the mountain. However, owners of the sand pit removed
a significant amount of sand from the pit essentially shaving the top of the
mountain off and hauling it away in trucks.
Now my point here is that if you scan my property and the sand pit with
Google Earth, Google Earth shows the elevations of the mountain before the
top was removed by the sand pit operation. Where the pit is clearly located,
Google says the elevations keeps increasing to reach a peak at the center of
the sand pit (where anyone's eyes will immediately show that the sand pit is
flat and leveled by the removal of the "old' peak of the mountain).
Thus, it is as though Google Earth uses algorithms based on "old" data, or
uses interpolation from grade contours, but it certainly does not use up to
date contour information. This is not a problem for most people, I guess,
but it is an anomaly for indiscriminant use of those contours.
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