HD Signal Level Needed ??

Thursday, May 10 2007, @1:13 PM (-0700 GMT)

Gentlemen,

I would like to present the following calculations for your critique
and comments. Is what I explain below right or wrong? If I'm wrong,
where is my mistake?

I live in San Clemente, CA, roughly 60 miles southeast of the Los
Angeles area TV transmitters. I do NOT have a "line of sight" (LOS)
situation; I'm behind low rolling hills and roughly 100 feet down
BELOW true LOS. I have an LG HD LCD TV presently connected to Cox
Cable. I would like to DUMP Cox and go "OTA." Is it possible? Is it
worth spending roughly $200 to find out? I live in an HOA area and
can't "do" a rooftop mount. My best placement possibility for the
antenna is either in the attic or near a northwest pointing window, on
the 2nd floor of our 2-story house, at a height of about 25 feet above
ground.

I did a careful investigation of my situation using www.tvfool.com.
This site gives me, (or so they say anyway), the theoretical received
TV signal level, in dBM, for my exact location. The signal level
prediction is based on the topology that exists between my home and
Los Angeles and their knowledge of the Los Angeles stations
transmitter power and radiation pattern.

As a "first cut," I assumed a "zero height" for my antenna above
ground as a "worst case." The calculations I got back from the web
site gave the following as the two STRONGEST TV stations: They were
KTLA-DT Channel 31 and KNBC-TV Channel 36. Their predicted signal
levels, at ground level, were -110.3 dBM and -112.9 dBM, respectively.
Very WEAK signals!

Now, since I can mount an antenna by a window or in the attic, at a
height of about 25 feet. I did the calculations again. the signal
levels at 25 feet above ground, instead of "0" feet were, -108.3 dBM
and -111.1 dBM, respectively, representing a gain of 1 to 2 dB. Before
you say: "But," I recognize that an attic mount would likely be worse
than by a window and the 1 or 2 dB "gain" would likely be a 3 dB loss
instead. Enough said on THAT. Still very WEAK signals.

Just for fun, I then assumed I could put the antenna on a tower at a
height of about 121.8 feet, for LOS, and look, line of sight, right at
the Los Angeles transmitters. It's interesting to note that, for LOS,
the signal levels rise considerably, to -58.1 dBM and -60.7 dBM,
respectively. About a 40 dB loss due to the dumb hills! Gee, do you
think my HOA would complain about a tower 121.8 feet high? Why?
Hahahahah. Maybe I could paint it green so it would "blend in?"

Now, if I were to use an Antennas Direct DB8 8-Bay Bow-Tie antenna,
with an approximate gain, (according to them), of about 15.8 dB, my
received signal levels for the two stations mentioned should increase,
using the 25 foot data, to about -92.5 dBM and -95.3 dBM,
respectively.

Then, if I use a Channel Master 7777 Low Noise Pre-Amp, having an
approximate gain of 26 dB, and a Noise Figure of 2.0 dB, the output
signal levels should increase to about -66.5 dBM and -69.3 dBM,
respectively. Signal levels half way reasonable now?? I wonder?

I'll approximate the loss in RG6 cable, at UHF, and a 50 foot length,
as about 2.5 dB. This should give signal levels, down at my TV in the
family room, of about -69 dBM and -71.8 dBM, respectively. Not TOO
bad, huh? Could be worse, but might not be enough?

O.K., so now here is the crux of the matter... My LG TV Owners Manual
was not, it so appears, written by someone with ANY degree of
technical knowledge. All it really TELLS me about their receiver is
that "It will receive Channels so and so, and the antenna input is 75
ohms." DUH! What an incomplete spec! Geez! What is the receiver
sensitivity? What signal level is NEEDED to produce a good quality
picture? What is the noise figure of the ATSC tuner? I'm given nothing
to work with.

So, gentlemen, at long last, here is a most important question of all:
What is the typical signal level, in dBM, needed to give a good
quality HD picture? How much signal do I need? Is a signal level of
about -70 dBM, (the average I'm seeing above), too LOW? Do I have to
have (say) -60 dBM at least? I don't know. does anyone/ Is there a web
site where the sensitivity of HD TV's are rated or compared?

About all I can imagine is that, because of the broader bandwidth
involved in HD, I'll need MORE signal than I would with analog for a
good picture.

Thank you! Comments appreciated. I'd like to TRY doing this, but not
if I don't have a snowballs chance in hell of receiving a decent
picture.

Jim
San Clemente, CA

Thursday, May 10 2007, @2:52 PM (-0700 GMT)

Thank you Elmo... I've been following the earlier thread on the
HOA situation. I agree that you are right, but I do not want the
hassle.

One point that I'm not sure was brought up on THAT thread is the
question of what is the situation when you BOUGHT your home in an HOA
area? Our tract is new and all buyers were required to 'sign away'
their rights on roof top antennas when they bought here in the last
few years. It would seem to me that, despite "the government trumps
the HOA," that when you AGREE to the "covenants" of a tract, when
buying there, that you are screwed? I'm not sure, but suspect a roof
top antenna woulds be a MAJOR battle.

Jim

On Thu, 10 May 2007 17:18:57 -0400, "Elmo P. Shagnasty"
wrote:

In article ,
Jim wrote:

I live in San Clemente, CA, roughly 60 miles southeast of the Los
Angeles area TV transmitters. I do NOT have a "line of sight" (LOS)
situation; I'm behind low rolling hills and roughly 100 feet down
BELOW true LOS. I have an LG HD LCD TV presently connected to Cox
Cable. I would like to DUMP Cox and go "OTA." Is it possible? Is it
worth spending roughly $200 to find out? I live in an HOA area and
can't "do" a rooftop mount.

Yes, you can. The feds--FCC--trumps your HOA.

Jim wrote:
Thursday, May 10 2007, @1:13 PM (-0700 GMT)

Gentlemen,

I would like to present the following calculations for your critique
and comments. Is what I explain below right or wrong? If I'm wrong,
where is my mistake?

I live in San Clemente, CA, roughly 60 miles southeast of the Los
Angeles area TV transmitters. I do NOT have a "line of sight" (LOS)
situation; I'm behind low rolling hills and roughly 100 feet down
BELOW true LOS. I have an LG HD LCD TV presently connected to Cox
Cable. I would like to DUMP Cox and go "OTA." Is it possible? Is it
worth spending roughly $200 to find out? I live in an HOA area and
can't "do" a rooftop mount. My best placement possibility for the
antenna is either in the attic or near a northwest pointing window, on
the 2nd floor of our 2-story house, at a height of about 25 feet above
ground.

I did a careful investigation of my situation using www.tvfool.com.
This site gives me, (or so they say anyway), the theoretical received
TV signal level, in dBM, for my exact location. The signal level
prediction is based on the topology that exists between my home and
Los Angeles and their knowledge of the Los Angeles stations
transmitter power and radiation pattern.

As a "first cut," I assumed a "zero height" for my antenna above
ground as a "worst case." The calculations I got back from the web
site gave the following as the two STRONGEST TV stations: They were
KTLA-DT Channel 31 and KNBC-TV Channel 36. Their predicted signal
levels, at ground level, were -110.3 dBM and -112.9 dBM, respectively.
Very WEAK signals!

Now, since I can mount an antenna by a window or in the attic, at a
height of about 25 feet. I did the calculations again. the signal
levels at 25 feet above ground, instead of "0" feet were, -108.3 dBM
and -111.1 dBM, respectively, representing a gain of 1 to 2 dB. Before
you say: "But," I recognize that an attic mount would likely be worse
than by a window and the 1 or 2 dB "gain" would likely be a 3 dB loss
instead. Enough said on THAT. Still very WEAK signals.

Just for fun, I then assumed I could put the antenna on a tower at a
height of about 121.8 feet, for LOS, and look, line of sight, right at
the Los Angeles transmitters. It's interesting to note that, for LOS,
the signal levels rise considerably, to -58.1 dBM and -60.7 dBM,
respectively. About a 40 dB loss due to the dumb hills! Gee, do you
think my HOA would complain about a tower 121.8 feet high? Why?
Hahahahah. Maybe I could paint it green so it would "blend in?"

Now, if I were to use an Antennas Direct DB8 8-Bay Bow-Tie antenna,
with an approximate gain, (according to them), of about 15.8 dB, my
received signal levels for the two stations mentioned should increase,
using the 25 foot data, to about -92.5 dBM and -95.3 dBM,
respectively.

Then, if I use a Channel Master 7777 Low Noise Pre-Amp, ...

You do not need LOS to get distant stations. According to tvfool.com I
have LOS to only 1 stations with the antenna in my attic with the rest
as 1 or 2 edges, but I get 17 digital stations with a CM 4221 with a CM
7777 pre-amp in my attic. My solid stations fall into the -80 to -114
dBm range based on a height of 12 meters. Based on your detailed
analysis, an attic or rooftop mount is needed. If you own your roof, the
HOA can not legally stop you from putting an antenna there provided it
fits over your roof area and falls in certain size limits.

The CM 4228 is an excellent choice for the LA area. It is one of the
best long range directional UHF antennas around and has decent pickup
for upper VHF 7 to 13 channels. You will need the upper VHF reception
after the analog shutdown in 2009 as several LA stations will switch
their digital channel to their current upper VHF analog channel.
tvfool.com is a great new resource, but it does warn you that the
numbers are not that exact. If you have not done so, check the FAQ and
3D visualization sticky threads at this avsforum.com forum:
http://www.avsforum.com/avs-vb/forumdisplay.php?f=25. You might want to
get the LA kmz file in the 3D visualization thread and try with Google
Earth.

Don't expect the LG manual to give specs that deep for the tuner. I
have seen manuals that don't even explain that ATSC = digital tuner.
Actually for digital, you need less signal than you do with a NTSC
analog station. That is my experience anyway. I get noisy pictures for
some distant but high power analog stations, but nice solid clean
pictures for the digital signal from the same broadcast tower. There are
many variables in this in UHF vs VHF vs ATSC inherent lower ERP for the
same coverage and so on, but many people have had excellent results for
long range digital reception now that most stations are finally at full
digital power. (If Bob Miller posts to this thread, ignore him as he is
the forum kook).

If I were you I would first try the CM 4228 in the attic without a
pre-amp to see what stations you can get. Run the RG-6 cable down the
stairs or through windows for a test setup. The LA broadcast towers are
way up there at over 6000 feet which gives them a height advantage seen
in few cities. If you get stations with dropouts then get the CM 7777
pre-amp which is probably the right one for your range from the towers.
Also, don't fix the antenna in place in the attic at the outset, but
instead arrange it so you can move the antenna around. Attic will often
have dead zones, so you need to try to find a good spot before you give
up on the attic. My CM 4221 is mounted on a large flat piece of scrap
wood with a attic mounting bracket bolting the PVC pipe mast to the
wood. I can move my antenna around by sliding it across the beams.

From your numbers, I suspect you will probably have to put the antenna
outdoors on the roof, but try it in stages. Fry's reportedly carries the
CM 4228 antenna, so you may be able to buy it locally which should give
you the option of returning it if it does not work.

Good luck and good OTA signal hunting!
Alan F

Jim wrote:


One point that I'm not sure was brought up on THAT thread is the
question of what is the situation when you BOUGHT your home in an HOA
area? Our tract is new and all buyers were required to 'sign away'
their rights on roof top antennas when they bought here in the last
few years. It would seem to me that, despite "the government trumps
the HOA," that when you AGREE to the "covenants" of a tract, when
buying there, that you are screwed? I'm not sure, but suspect a roof
top antenna woulds be a MAJOR battle.


It is not unusual to have a few restictions in CC&Rs that are trumped by
law after they are written. The HOA has no obilgation to remove them,
but they have a duty to not enforce them.

On Thu, 10 May 2007 14:00:18 -0700, Jim wrote:

I live in San Clemente, CA, roughly 60 miles southeast of the Los
Angeles area TV transmitters. I do NOT have a "line of sight" (LOS)
situation; I'm behind low rolling hills and roughly 100 feet down
BELOW true LOS. I have an LG HD LCD TV presently connected to Cox
Cable. I would like to DUMP Cox and go "OTA." Is it possible? Is it
worth spending roughly $200 to find out?

People in San Diego get the LA digital stations. Should be a piece of cake
where you are. 5ft tripod mount with a 5 ft mast and Channel master CM5228
on the roof will get you both LA and San Diego stattions.

I live in an HOA area and can't "do" a rooftop mount.

Yes you can, but it would probably work OK in the attic if you don't want
to stand up for your rights.

--
Want the ultimate in free OTA SD/HDTV Recorder? http://mythtv.org
http://mysettopbox.tv/knoppmyth.html Usenet alt.video.ptv.mythtv
My server http://wesnewell.no-ip.com/cpu.php
HD Tivo S3 compared http://wesnewell.no-ip.com/mythtivo.htm

"Jim" wrote in message
...

Thursday, May 10 2007, @2:52 PM (-0700 GMT)

Thank you Elmo... I've been following the earlier thread on the
HOA situation. I agree that you are right, but I do not want the
hassle.

One point that I'm not sure was brought up on THAT thread is the
question of what is the situation when you BOUGHT your home in an HOA
area? Our tract is new and all buyers were required to 'sign away'
their rights on roof top antennas when they bought here in the last
few years. It would seem to me that, despite "the government trumps
the HOA," that when you AGREE to the "covenants" of a tract, when
buying there, that you are screwed? I'm not sure, but suspect a roof
top antenna woulds be a MAJOR battle.

Jim


When the FCC ruling came down I had satellite service which at the time
couldn't offer local programming. Left with a choice between getting the
locals for free OTA or paying the cable company I decided to install a
rooftop antenna. I had tried an attic installation and because of the
elevation of my home it didn't bring in all the channels.

Shortly after installing the antenna at the least obvious place on my roof
at the rear of the house where there are no neighbors behind me to object I
received a letter via registered mail. It was from the HOA stating that
while they could see their way to allowing the dish that either the antenna
came down or they would take legal action. In reply I sent them a copy of
the FCC rulings with the interesting passages highlighted.

Given the FACT that they would have to shoulder the burden of paying both
attorneys until the issue was resolved and with no chance of prevailing in
the action, that was the last I heard from them on the matter. While they
could take the time to draft a threatening letter they could or would not
take the time to retract their demands either written or verbal. Given their
lack of basic courtesy in the manner and the fact that I went out of my way
to place the antenna in the least objection place I was much less sensitive
to their concerns when I replaced the antenna.

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.

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



On Thu, 10 May 2007 22:09:59 GMT, Alan F
wrote:

Jim wrote:
Thursday, May 10 2007, @1:13 PM (-0700 GMT)

Gentlemen,

I would like to present the following calculations for your critique
and comments. Is what I explain below right or wrong? If I'm wrong,
where is my mistake?

I live in San Clemente, CA, roughly 60 miles southeast of the Los
Angeles area TV transmitters. I do NOT have a "line of sight" (LOS)
situation; I'm behind low rolling hills and roughly 100 feet down
BELOW true LOS. I have an LG HD LCD TV presently connected to Cox
Cable. I would like to DUMP Cox and go "OTA." Is it possible? Is it
worth spending roughly $200 to find out? I live in an HOA area and
can't "do" a rooftop mount. My best placement possibility for the
antenna is either in the attic or near a northwest pointing window, on
the 2nd floor of our 2-story house, at a height of about 25 feet above
ground.

I did a careful investigation of my situation using www.tvfool.com.
This site gives me, (or so they say anyway), the theoretical received
TV signal level, in dBM, for my exact location. The signal level
prediction is based on the topology that exists between my home and
Los Angeles and their knowledge of the Los Angeles stations
transmitter power and radiation pattern.

As a "first cut," I assumed a "zero height" for my antenna above
ground as a "worst case." The calculations I got back from the web
site gave the following as the two STRONGEST TV stations: They were
KTLA-DT Channel 31 and KNBC-TV Channel 36. Their predicted signal
levels, at ground level, were -110.3 dBM and -112.9 dBM, respectively.
Very WEAK signals!

Now, since I can mount an antenna by a window or in the attic, at a
height of about 25 feet. I did the calculations again. the signal
levels at 25 feet above ground, instead of "0" feet were, -108.3 dBM
and -111.1 dBM, respectively, representing a gain of 1 to 2 dB. Before
you say: "But," I recognize that an attic mount would likely be worse
than by a window and the 1 or 2 dB "gain" would likely be a 3 dB loss
instead. Enough said on THAT. Still very WEAK signals.

Just for fun, I then assumed I could put the antenna on a tower at a
height of about 121.8 feet, for LOS, and look, line of sight, right at
the Los Angeles transmitters. It's interesting to note that, for LOS,
the signal levels rise considerably, to -58.1 dBM and -60.7 dBM,
respectively. About a 40 dB loss due to the dumb hills! Gee, do you
think my HOA would complain about a tower 121.8 feet high? Why?
Hahahahah. Maybe I could paint it green so it would "blend in?"

Now, if I were to use an Antennas Direct DB8 8-Bay Bow-Tie antenna,
with an approximate gain, (according to them), of about 15.8 dB, my
received signal levels for the two stations mentioned should increase,
using the 25 foot data, to about -92.5 dBM and -95.3 dBM,
respectively.

Then, if I use a Channel Master 7777 Low Noise Pre-Amp, ...

You do not need LOS to get distant stations. According to tvfool.com I
have LOS to only 1 stations with the antenna in my attic with the rest
as 1 or 2 edges, but I get 17 digital stations with a CM 4221 with a CM
7777 pre-amp in my attic. My solid stations fall into the -80 to -114
dBm range based on a height of 12 meters. Based on your detailed
analysis, an attic or rooftop mount is needed. If you own your roof, the
HOA can not legally stop you from putting an antenna there provided it
fits over your roof area and falls in certain size limits.

The CM 4228 is an excellent choice for the LA area. It is one of the
best long range directional UHF antennas around and has decent pickup
for upper VHF 7 to 13 channels. You will need the upper VHF reception
after the analog shutdown in 2009 as several LA stations will switch
their digital channel to their current upper VHF analog channel.
tvfool.com is a great new resource, but it does warn you that the
numbers are not that exact. If you have not done so, check the FAQ and
3D visualization sticky threads at this avsforum.com forum:
http://www.avsforum.com/avs-vb/forumdisplay.php?f=25. You might want to
get the LA kmz file in the 3D visualization thread and try with Google
Earth.

Don't expect the LG manual to give specs that deep for the tuner. I
have seen manuals that don't even explain that ATSC = digital tuner.
Actually for digital, you need less signal than you do with a NTSC
analog station. That is my experience anyway. I get noisy pictures for
some distant but high power analog stations, but nice solid clean
pictures for the digital signal from the same broadcast tower. There are
many variables in this in UHF vs VHF vs ATSC inherent lower ERP for the
same coverage and so on, but many people have had excellent results for
long range digital reception now that most stations are finally at full
digital power. (If Bob Miller posts to this thread, ignore him as he is
the forum kook).

If I were you I would first try the CM 4228 in the attic without a
pre-amp to see what stations you can get. Run the RG-6 cable down the
stairs or through windows for a test setup. The LA broadcast towers are
way up there at over 6000 feet which gives them a height advantage seen
in few cities. If you get stations with dropouts then get the CM 7777
pre-amp which is probably the right one for your range from the towers.
Also, don't fix the antenna in place in the attic at the outset, but
instead arrange it so you can move the antenna around. Attic will often
have dead zones, so you need to try to find a good spot before you give
up on the attic. My CM 4221 is mounted on a large flat piece of scrap
wood with a attic mounting bracket bolting the PVC pipe mast to the
wood. I can move my antenna around by sliding it across the beams.

From your numbers, I suspect you will probably have to put the antenna
outdoors on the roof, but try it in stages. Fry's reportedly carries the
CM 4228 antenna, so you may be able to buy it locally which should give
you the option of returning it if it does not work.

Good luck and good OTA signal hunting!
Alan F

"Jim" wrote in message
...

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.

The problem in Chicago is many of the digital stations are running on an
adjacent channel. For example CBS analog ch2 is on digital ch3 running
1/10th the power. There are similar situations on many of the UHF channels.
Many of the problems with putting a lot of gain the amplifier is the analog
adjacent channel overloads the tuner when tuning the weaker digital channel.
These problems will all end after the digital transition. You may be in a
similar situation in S. California.

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.

-114 is getting to the low end of signal usability. Subjectively, signal
level that would give a watchable but snowy analog picture will deliver a
perfect digital reception.

(snip)
Jim
San Clemente

David

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.

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"
he
http://www.avsforum.com/avs-vb/forum...sprune=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

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
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.

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"
he
http://www.avsforum.com/avs-vb/forum...sprune=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