[opendtv] Re: Reception range

For those interested, I posted a copy of "basic" WBFF coverage stats (analog and digital) here:
<http://www.yousendit.com/transfer.php?action=download&ufid=120B2E741B8CCF33>

Manfredi, Albert E wrote: 
Richard Hollandsworth wrote:

The RADIO MOBILE implementation of LR-ITM, with a modern
graphic interface, is available as a free download for
Windows op sys:
http://www.cplus.org/rmw/english1.html
However, the clutter loss model is inadequate and does not
readily support input of local parameters, such as
indoor/attic loss, sensitivity loss due to antenna VSWR
and system noise figure calculation. It is also difficult
to define a multiplicity of different TX and RX antenna
gain patterns and to calculate co-channel and adjacent
channel interference effects.

Lots of interesting info in your post, Richard. What's missing, though,
is that I wasn't looking for an absolute prediction of receivability of
a TV station. I was trying to figure out why one station, WBFF-DT, was
so different from all the others. This was a comparative analysis. Any
number of shaky assumptions, especially at the receiver end, cancel out.
They are equally right or equally wrong for all data points.

Aside from the one Annapolis example, all other stations were from
Baltimore, located very close together in Baltimore. Which means that a
lot of assumptions about the terrain, trees, etc. between source and
destination also cancel out. We're talking almost 50 miles away, as the
crow flies. Azimuths don't change that much from that distance. As
confirmed also by antennaweb.

I already knew that multipath was not a major issue for these stations,
by checking their analog channel. The distant stations do not suffer too
much from multipath, probably because the reflections are just too weak.

What I showed fairly convincingly, I think, is that all the marginal
stations from far away resulted in almost identical signal strength at
the receiver, which was about -73 dBm threshold level. In absolute
terms, this number could be off by several dB. It could be -80 dBm in
reality, for example. But what matters is that it was consistent for all
-- except WBFF-DT. Interestingly enough, even the Annapolis station
resulted in that signal strength at the receiver. So the Hata model did
quite well.

Mark Aitken's response is the one that mattered. The FCC had not updated
its table of stations operating under a STA. With the ERP for WBFF
corrected, everything is consistent for the marginal stations. Not only
that, but the correlation is also excellent for the stronger stations,
when comparing their transmitter configurations against the Accurian's
signal strength meter. So that pretty much settles it.

Bert
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Regards,
Mark A. Aitken
Director, Advanced Technology
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