Dear Sal:
Thank you. I should have taken the trouble to think about the
difference.
Thinking back to the extensive tests of (analog) TV performance that
were performed in the 50s, makes the 64 dBu understandable. At that time,
the noise-figures of TV sets were, by modern standards, poor. It was also
found - without surprise - that people would tolerate a poor picture is the
sound was OK, thus followed the preferred ratio of video to sound carrier.

As noise figures fell, many of us became accustomed to satisfactory
performance using simple, indoor antennas. That is another way of saying
that the ERP standards of the 50s were overkill in the 21st century. With
the advent of DTV, outside antennas will once again become the norm.

What seems to be missing - at least until competitive pressure catches
up - is an effective way to compare NF of TV sets or converter boxes. One
needs a box that presents a small-signal DTV signal.

Again, thanks. 73, Mac N8TT
--
J. McLaughlin; Michigan, USA
Home:
"Sal M. Onella" wrote in message
...

"J. Mc Laughlin" wrote in message
.. .
... and some stations will be transmitting DTV on a third channel (not
the
present analog nor the present DTV channel)

I have also found that a number of stations have applied for changes (so
far
they seem to be ERP changes) to what is contained in the eighth FCC
report
of March 2008. One needs to go to the FCC site and enter call sign of
each
station to find the present information.

A surprise to me is that the coverage contour for analog TV is 64 dBu and
for DTV is 41 dBu - a difference of 23 db. However, the reductions of
ERP
do not seem to be that large. Stations that are now a bit weak may be
unusable after Feb. 2009.

73, Mac N8TT

The DTV RF signal needs to be about 17 dB out of the noise to work and
produce a nice, clean picture. Analog TV RF signal needs to be about 40
dB
out of the noise for a snow-free picture on screen. Holy crap, that's 23
dB! Coincidence? I think not.

In my case, I get generally horrible analog performance from Los Angeles
stations, 124 miles away. However, I usually have a half-dozen digital
pictures from there and they are, of course, perfect whenever they come
in.

By the way, the original question -- as if anybody really remembered it --
is answered he

http://rabbitears.info/market.php

That site has a grunch of data. See the links at the top. This guy is
working his butt off.

73,
"Sal" KD6VKW