On Mon, 18 Apr 2005 23:50:43 UTC, Andy Wade
wrote:

tony sayer wrote:

They cannot take into account local obstructions like buildings and
other obstructions other than adding in an "urban clutter" factor which
can be very variable!...

Oh yes they can. The UK planning model for DTT uses real clutter data -
see for example:

http://www.bbc.co.uk/rd/pubs/whp/whp048.shtml

"The paper outlines the approach for predicting received field strength
with particular discussion of profile extraction, radial prediction and
the use of clutter data to take into account the effect of buildings and
trees."

My original point was that they had apparently taken a fixed point of
reference for my postcode area (rather than postcode). And that area
extends from here (about 25m a.s.l.) down to sea level. Houses at sea
level can't 'see' the transmitter to the south-east, so they gave data
for the transmitter that *can* be seen (lower power, lower antenna,
further away) to the west.

The clutter factor didn't enter into it for me; just contours.

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