Re: HD Signal Level Needed ??

Friday, May 11 2007, @2:44 PM (-0700 GMT)

Thank you David and Alan... Great input! :)

Well, I guess I'll know for sure in a week or two when the DB8 and the
CM7775 get here.

I hadn't thought about the fact that the UHF only DB8 is so SMALL
compared with the analog type huge yagis I'm used to thinking about. I
think the DB8 is (roughly) one meter square, not much bigger than a
Direct TV or Dish Network parabolic dish. Maybe, just maybe, my
neighbors would not scream and hollar if I put it at the far back side
of the house, on the roof, and just barely high enough to clear the
roof line? Hmmm The testing will settle it one way or the other.
:)

Thank you,

Jim
San Clemente, CA about 2 miles from 'Tricky Dicks' Western White house




On Fri, 11 May 2007 19:25:57 GMT, Alan F <afiggatt1@xxxxxxxxxxxxxx>
wrote:

Jim wrote:
Friday, May 11 2007, @ 7:25 AM (-0700 GMT)

Alan,

Thank you for the VERY descrikptive and meaningful post. Very GOOD
info!

I'm really amazed to learn that I need LESS signal with digital than
analog. That real was not what I expected. I'm an 'old school'
RF/Microwave engineer and really thought the opposite. To me, the
bandwidth of an HD signal seemed to spell out that it would 'take
more' to receive. :) Oh well, its GREAT to learn new things! I'm
amazed that, based on looking at my 'number crunching,' that you feel
an attic antenna WILL work in my situation. Gee, that would be GREAT.
I could fight the HOA, and, as I've been told by others in this group,
they WOULD lose, but then I want to be a 'good neighbor' and many may
be angry with me if I 'junk up' the neighborhood with a rooftop
antenna. :)

Are you pretty confident about the signal levels you mentioned? Can I
really expect a decent picture with signal levels in the -80 to -114
dBM range at my HD sets antenna input? It seems low to me, but again,
I'm thinking in analog terms. :) If that's really TRUE, I should be
able to get usable OTA reception.

I can't say that the antenna in the attic will work for sure. Just too
many variables, given your range to the broadcast towers, to say one way
or the other. You could have a building or tall clump of trees in the
way or the construction materials used in the house & roof cut the
signal down too much. The only way to find out, short of spending a lot
of money on a professional installer who would bring a spectrum analyzer
& test antennas, is to get a CM 4228 - Frys Electronics is known to
carry them, a 50' long RG-6 cable, set it up on the back deck or
upstairs first, then the attic and give it a go. I think it would be fun
for a RF engineer to try.

I went back to tvfool.com and entered my exact long & lat and 40' for
the antenna. Shows the local digital stations I get with a CM 4221 in
the attic of my townhouse as ranging from -68 to -108 dBm. For some of
those weaker stations at 43 miles, my antenna is looking lengthwise down
the row of townhouses through the top of 3 THs which are slightly
uphill. I would get better results if I put the antenna on the roof, but
the roof is way up there and I would have to get a professional
installer to put it up there with a rotator.

I may someday put the antenna on the roof, just to get a few more
remote stations. While I have a HOA, they don't try to restrict antennas
on the roof. I imagine if it were not for the FCC, I'm sure there are
control freaks at my HOA who would love to ban antennas above the roof
line. I personally think an antenna on the roof is a beautiful and
functional sight. :D

One caveat with tvfool.com is that it may show a number of low power
digital stations that are not on the air yet. Most Class A & low power
stations will have to wait until they shut off their analog signal
before they can fire up their digital signal in what is called a digital
flash cut conversion. The digital entries for the LP station started to
show in the FCC database a few months ago, but those digital LP stations
are not likely to go on the air until close to the shutdown day on
February 17, 2009. For the countdown clock, go to www.dtv.gov.

One thing I should've mentioned in my original post: I want to 'dump
Cox' but what I really meant was to dump their local channel HD and
their DVR. I've heard that Cox compresses quite a bit and that OTA HD,
if I can get it, will provide a better picture. Is this true? I want
to keep Cox's 'Basic Cable' and their 'Expanded Basic' so as to
continue to receive things like 'The History Channel,' 'Fox News,'
etc. I would use a TiVo Series 3 for OTA HD recording.

Thanks to you, Mr. Shag'nNasty, and other posters for GOOD input. Why
don't we meet here in S.C. at a local pizza place for a pitcher ? :)

Jim
San Clemente

You have to check with the local threads for the LA area to see how
much compression Cox does there. The large cable companies - Comcast,
Time Warner, Cox - all consists of many territories cobbled together
from different cable companies they took over / brought out over the
years. In one area, they may have newer equipment and more bandwidth so
they don't need to re-compress the HD locals. In other areas, they are
bandwidth limited until they shut down most of the analog channels.

Look for the LA threads under the sticky: "United States Thread index"
here:
http://www.avsforum.com/avs-vb/forumdisplay.php?s=&daysprune=30&f=45.
avsforum.com is one of the best net resources for all things HD.

Many cable companies do not provide all the HD locals, which is
another reason to put up an antenna. In my case, I switched to Verizon
Fios from Adelphia/Comcast last fall and get all the Washington DC HD
locals via Verizon. When I moved in to my townhouse in 2005, Adelphia
did not provide the local PBS, WB and UPN stations on the HD tier, so I
put up an antenna (had fun experimenting with it too). They added the
DC PBS station a few months later, but that was it. I am also able to
get the Baltimore HD stations with the antenna which is a nice plus.
Comcast officially took over the local Adelphia system (Loudoun county,
VA) last August and still does not have the local CW or My Network
stations in their HD line-up. So if I was stuck with Comcast or either
of the 2 satellite providers, I would have to use an antenna to get CW
or My Network in HD. With the antenna, I get stations - both HD and SD -
& sub-channels that are likely to never show up on cable, DBS, or Fios.

One warning about the Series 3 Tivo and that is you should research
whether your Cox system is planning to use "switched Digital Video". Do
a search for it.

Whew, this was a long post. I hope this helps, not only yourself, but
other readers who may be thinking about putting up an antenna! Good luck.

Alan F





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