Bob Eager wrote:

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.

I was just responding to Tony's more general point about the use/non-use
of clutter data. Whether it's used in the public postcode predictor I'm
not sure, but that does tend to err on the pessimistic side, to avoid
disappointment due to marginal reception. As you say postcodes can be
too coarse a granularity - the % population served predictions are done
on the basis of 100m squares, IIRC, and they're working toward getting
that down to 50m. There might be other reasons why it doesn't offer TX
B as an option for you, such as not being free from excessive co-channel
or adjacent channel interference for =99% of the time.

It would be nice if there were a Web-based predictor that accepted an
NGR and RX antenna height and returned predicted field strengths for
candidate TXs together with a list of potential interferers and their
directions, etc. - but with all the spectrum planning people busy on the
Great Switch-over Plan, that won't happen.

--
Andy