[opendtv] Re: VHF Stations Seek Solutions for Reception Problems, by Doug Lung

A couple bad tests with DTV at WRAL and KCIU apparently trumped a dozen 
positive on-air tests with analog:
http://www.tvtechnology.com/article/67946
http://cat.inist.fr/?aModele=afficheN&cpsidt=1845203
http://ieeexplore.ieee.org/Xplore/login.jsp?url=http%3A%2F%2Fieeexplore.ieee.org%2Fiel5%2F30%2F17220%2F00793638.pdf&authDecision=-203

holl_ands

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--- On Mon, 6/29/09, Dale Kelly <dalekelly@xxxxxxxxxxx> wrote:

From: Dale Kelly <dalekelly@xxxxxxxxxxx>
Subject: [opendtv] Re: VHF Stations Seek Solutions for Reception Problems, by 
Doug Lung
To: opendtv@xxxxxxxxxxxxx
Date: Monday, June 29, 2009, 3:48 PM

Bert wrote:
 "Doug Lung always has interesting insights":
I've known Doug for a number of years and he has always been a reliable
source of information and analysis.

 "One of them is use of circular polarization":
CP simply works and at all frequencies, though possibly better at some than
others. I have constructed and/or tested a large number of CP facilities for
VHF and UHF TV as well as for FM radio. It significantly improves reception
where marginal antennas exist and where CP receive antennas are used.
Before CP. FM radio was virtually useless in automobiles until that
transmission mode was adopted by broadcasters.

It has been said by some, but with no supporting evidence that I know of,
that CP won't work well for DTV. However, I know of no reason why it will
not improve reception in all services and it seems to me that DTV mobile
simply will not work without it.

Dale


-----Original Message-----
From: opendtv-bounce@xxxxxxxxxxxxx
[mailto:opendtv-bounce@xxxxxxxxxxxxx]On Behalf Of Manfredi, Albert E
Sent: Monday, June 29, 2009 7:58 AM
To: opendtv@xxxxxxxxxxxxx
Subject: [opendtv] Re: VHF Stations Seek Solutions for Reception
Problems, by Doug Lung


Dale Kelly posted:

http://www.tvtechnology.com/article/83128

Doug Lung always has interesting insights. One of them is use of
circular polarization.

The situation here, specifically with WJLA-TV on VHF Channel 7, has been
steadily improving at our location. I wish I knew what they had done.

From no reception on the 12th at noon, to constant pixellation and no
sound that same evening, to sound with constant image problems in the
days that followed, last week we finally got solid reception in the
upstairs system (the one with RS double bowtie and 3rd gen receiver),
and last night I got virtually solid reception donwstairs too (the dual
Antenna Direct DB4s in fireplace).

Only minor adjustments done at our end. A slight turning of the RS
antenna upstairs, and a bit of VHF relector assistance downstairs.

When it works, VHF is nice for its consistency. It seems that whatever
the reception quality is tends to remain the same over long periods of
time. Compared with UHF, when operating close to the margin, which tends
to drop off entirely then come back.

Bert

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