Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems.

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Default OTA tuner sensitivity

I made an interesting observation today and thought that I would
relate it
to the group. I use a set top converter in the shop to receive OTA
signals
from my antenna. I just put up the antenna this past Fall so I don't
have
much history with this particular antenna. However I can say without
hesitation that for the past 33 years at this same location as soon as
the
leaves start to come out in the Spring, our UHF reception would begin
to
degrade. We are in a deep fringe area so UHF reception has always been
boarder line on many channels. Obviously digital has made that
situation
even more difficult for us. With the new installation though, an old
Channel Master parabolic that I resurrected, with a Winegard GA8780
preamp,
things have improved quite a bit over the old Yagi we had been using.

So today I just finished up a three year old Samsung and auto
programmed it
off my antenna. I noted many more channels than my bench converter had
previously picked up and stored. So then I went to the converter and
manually entered the new channels. To my surprise I did get most, but
not
all of the new ones. So perhaps propagation has changed somewhat. I
don't
know. In any case there is definitely a difference in front ends on
these
two receivers.

There was this one channel in particular that looked fine on the
Samsung
but would intermittently very lightly "pixelate" when processed
through my
set top converter. I removed the 2 way splitter feeding the bench and
the
set and fed the bench directly thereby increasing the level to the
bench by
3DB. The weak channel was improved but still would break up, (but less
pronounced) on occasion.

What frustrates me is that except for the OSD "bar graph" signal
indicators
on most digital sets today, I really can't tell what the actual signal
strength of a particular station is anymore. It used to be so easy. I
would
connect up my old Sadelco analog meter to a cable or antenna coax and
simply read the carrier level. Now that we have two different types of
TV
broadcasting systems to deal with all my equipment is obsolete.
So I have two questions to pose to the group:
1. Has anyone noted consistent instances where one tuner is noticeably
"hotter" than the other? That is to say one set that will perform with
a
weak signal where the next being fed the same signal might break up?
This
slight difference in the front ends, which might never be detected on
cable
could affect antenna users in fringe areas like myself. In fact I
don't
know if I ever would have noticed this if I hadn't been running two
different sets in the shop at the same time).
2. If it's economically feasible I would like to be able to read
signal
level directly on a test instrument. This would be useful on antenna
jobs
as well as cable distribution systems. Is there such an affordable
instrument available for this purpose? Thanks, Lenny


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Default OTA tuner sensitivity

On Sat, 31 Dec 2011 15:42:18 -0800 (PST), klem kedidelhopper
wrote:

What frustrates me is that except for the OSD "bar graph" signal
indicators
on most digital sets today, I really can't tell what the actual signal
strength of a particular station is anymore.


Some TV's and converters have diagnostic displays that shows some
details. When you disclose exact model numbers of the receivers and
converters that you're testing, it might be possible to find the
diagnostic page.

It used to be so easy. I
would
connect up my old Sadelco analog meter to a cable or antenna coax and
simply read the carrier level. Now that we have two different types of
TV
broadcasting systems to deal with all my equipment is obsolete.


Baloney. My antique Sadelco 719B meter (the one with FOUR 9v
batteries), still works. It indicates the signal strength of the OTA
digital stuff just fine. It won't demodulate the audio, but the
signal strength is still usable. What model Sadelco are you using?

1. Has anyone noted consistent instances where one tuner is noticeably
"hotter" than the other? That is to say one set that will perform with
a
weak signal where the next being fed the same signal might break up?
This
slight difference in the front ends, which might never be detected on
cable
could affect antenna users in fringe areas like myself. In fact I
don't
know if I ever would have noticed this if I hadn't been running two
different sets in the shop at the same time).


Nope. That's because, like you, I'm using a tower mounted amplifier.
With such an arrangement, the RX sensitivity is almost totally
determined by the amplifier noise figure. You could compare a high
quality receiver with a piece of junk, and they would be about the
same sensitivity. Now, there are some things that will make a
receiver worse, such as digital noise in the receiver front end,
overload by adjacent channel stations, ability to deal with
reflections, etc. Hard to tell from here.

2. If it's economically feasible I would like to be able to read
signal
level directly on a test instrument. This would be useful on antenna
jobs
as well as cable distribution systems. Is there such an affordable
instrument available for this purpose? Thanks, Lenny


I wouldn't mind one of those myself. I used to own one of those
government subsidized converter boxes (Zenith DTT901), that had an on
screen diagnostic page. All CECB certified converters are required to
have an on screen signal strength meter. However, there's a catch.
Most converters do not show signal strength. They show "signal
quality" which is usually calculated from the BER (bit error rate) of
the decoded DTV signal. This is somewhat related to signal strength,
but can easily be trashed by adjacent channel junk, internal digital
noise, reflections, etc.

Another possibility would be to purchase a laptop or PC based ATSC
tuner, and use that as the receiver. With luck and diligence, you
might be able to find some kind of open source diagnostic program that
can be used as a tester. At a minimum, something that dumps PSIP data
from the station.

There's plenty of test equipment available:
www.ebay.com/sch/i.html?_nkw=digital+tv+signal+finder+-satellite
but most of them look rather lame.

Better:
http://www.horizonhge.com (in UK)


--
Jeff Liebermann
150 Felker St #D
http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
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Default OTA tuner sensitivity

"which is usually calculated from the BER (bit error rate) of
the decoded DTV signal."

Sweet. They are guaging the quality of the signal, for their
particular product, chipset, whatever. This gets me wondering, for
one, what if you ar einstalling an antenna without a rotor ? I happen
to know a few places in this city where the reflections are so bad
that you NEED cable. Just the lay of the land and a bunch of
buildings. It didn't work with analog, even though there is plenty of
signal strength. This is extremely bad folks, but I don't live there.
At my house analog was quite good. I did get some DX out of the attic
but because I needed multiple outlets, the amp just didn't do the out
of town stations justice. It's really not worth big bucks, basic
stripped cable is cheap enough.

But signal quality is a whole nother thing here. More processing power
could mean being able to decode a signal that would be unusable to a
lesser reciever. So how do we test this ? First of all there must be
adequate signal strength. Then as far as I can figure feed a signal
into an amp and then a splitter to two different recievers and find
out which one corrects and/or recovers from the errors the best. Split
AFTER the amp, you can screw with the signal level before the amp to
put the recievers through their paces.

There was already contrived a ghost eliminator for NTSC, though I have
never seen one I have read the specs on it and how it works, vertical
interval stuff again..... I thought they should be able to do it off
the old usual VITS but.......

So of course this device uses multiple time delays and nulls out
components based upon what was detected in the reference, yada yada
yada. This is all digital of course, well now WE ARE TALKING DIGITAL
so that should already be built I would think. The ability to correct
for multipath. Sorta lika a WAAY adaptable COMB filter.

So it is probably in that area in these recievers that determines the
optimum performance. Also some people need different parameters than
others. In this case, deep fringe, well it may be easier to deal with
if you get enough aerial, altitude and amplification, the three As.
But in an urban environment, more processing power would help more
than a kickass front end.

I think I could easily devise a setup to test these things, but I
wonder if it's worth it. Who would pay me ? Concievably some magazine
or something, one of the ones that review video equipment. OK that
makes sense except for one thing. People who read magazines to figure
out which TV to buy are not using convertor boxes. They got HD sets on
dishes or cable or internet TV or something. The only antenna in their
house may be on the router.

J
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Default OTA tuner sensitivity

klem kedidelhopper wrote:
I made an interesting observation today and thought that I would
relate it
to the group. I use a set top converter in the shop to receive OTA
signals
from my antenna. I just put up the antenna this past Fall so I don't
have
much history with this particular antenna. However I can say without
hesitation that for the past 33 years at this same location as soon as
the
leaves start to come out in the Spring, our UHF reception would begin
to
degrade. We are in a deep fringe area so UHF reception has always been
boarder line on many channels. Obviously digital has made that
situation
even more difficult for us. With the new installation though, an old
Channel Master parabolic that I resurrected, with a Winegard GA8780
preamp,
things have improved quite a bit over the old Yagi we had been using.

So today I just finished up a three year old Samsung and auto
programmed it
off my antenna. I noted many more channels than my bench converter had
previously picked up and stored. So then I went to the converter and
manually entered the new channels. To my surprise I did get most, but
not
all of the new ones. So perhaps propagation has changed somewhat. I
don't
know. In any case there is definitely a difference in front ends on
these
two receivers.

There was this one channel in particular that looked fine on the
Samsung
but would intermittently very lightly "pixelate" when processed
through my
set top converter. I removed the 2 way splitter feeding the bench and
the
set and fed the bench directly thereby increasing the level to the
bench by
3DB. The weak channel was improved but still would break up, (but less
pronounced) on occasion.

What frustrates me is that except for the OSD "bar graph" signal
indicators
on most digital sets today, I really can't tell what the actual signal
strength of a particular station is anymore. It used to be so easy. I
would
connect up my old Sadelco analog meter to a cable or antenna coax and
simply read the carrier level. Now that we have two different types of
TV
broadcasting systems to deal with all my equipment is obsolete.
So I have two questions to pose to the group:
1. Has anyone noted consistent instances where one tuner is noticeably
"hotter" than the other? That is to say one set that will perform with
a
weak signal where the next being fed the same signal might break up?
This
slight difference in the front ends, which might never be detected on
cable
could affect antenna users in fringe areas like myself. In fact I
don't
know if I ever would have noticed this if I hadn't been running two
different sets in the shop at the same time).
2. If it's economically feasible I would like to be able to read
signal
level directly on a test instrument. This would be useful on antenna
jobs
as well as cable distribution systems. Is there such an affordable
instrument available for this purpose? Thanks, Lenny


I didn't figger out from your post where you're located. Makes a
difference.
Here in the good ole USA, OTA HDTV sucks. Encoding was picked by
lobbyists, not engineers.

I'm only 10 miles from the transmitters, but there's a hill in the middle
and a two-story metal pole building in my neighbor's yard. It's
multipath city here. Ability to decode a channel also depends
on the season and how many leaves the intermediate trees have.

I have a combo VHF/UHF antenna on a rotor, but if you wanna record more
than one thing at a time, you can't be turning the antenna.

The Zenith DTT901's work pretty well, unless it's raining hard, but
the output isn't HD.

I have several older cable boxes that work on some channels.
It's particularly annoying on some boxes that there's no way to
add channels. If you need a different antenna direction to detect
a channel, you can't find all the channels with the auto scan.

The ATSC tuner card in the PC works the worst.
And it's not signal strength.
I put a variable attenuator in the antenna line and tweak it per channel
for fewest dropouts.

Before the big switch, when most of the ATSC channels were on UHF, signals
were much better. After the switch, when they went back to VHF ATSC,
it got much worse.

I put the signal on a spectrum analyzer. There's no correlation between
signal strength and stability of the picture. The "Bart's head" display
is supposed to be flat on top. There is a correlation between the flatness
of the top and the stability of the picture.

I have a friend in the industry. He won't disclose details, but he claims
that the math to de-multipath the signal exists. But it takes more
computing horsepower than you can get into a cheapo set top box with current
technology.

I'm unwilling to spend much money on this. The whole idea of free TV
is that it be FREE. I'd much rather have NTSC quailty than "no signal"
scrolling across the screen of what I thought I'd taped.
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Default OTA tuner sensitivity

On Jan 1, 5:00*am, mike wrote:
klem kedidelhopper wrote:
I made an interesting observation today and thought that I would
relate it
to the group. I use a set top converter in the shop to receive OTA
signals
from my antenna. I just put up the antenna this past Fall so I don't
have
much history with this particular antenna. However I can say without
hesitation that for the past 33 years at this same location as soon as
the
leaves start to come out in the Spring, our UHF reception would begin
to
degrade. We are in a deep fringe area so UHF reception has always been
boarder line on many channels. Obviously digital has made that
situation
even more difficult for us. With the new installation though, an old
Channel Master parabolic that I resurrected, with a Winegard GA8780
preamp,
things have improved quite a bit over the old Yagi we had been using.


So today I just finished up a three year old Samsung and auto
programmed it
off my antenna. I noted many more channels than my bench converter had
previously picked up and stored. So then I went to the converter and
manually entered the new channels. To my surprise I did get most, but
not
all of the new ones. So perhaps propagation has changed somewhat. I
don't
know. In any case there is definitely a difference in front ends on
these
two receivers.


There was this one channel in particular that looked fine on the
Samsung
but would intermittently very lightly "pixelate" when processed
through my
set top converter. I removed the 2 way splitter feeding the bench and
the
set and fed the bench directly thereby increasing the level to the
bench by
3DB. The weak channel was improved but still would break up, (but less
pronounced) on occasion.


What frustrates me is that except for the OSD "bar graph" signal
indicators
on most digital sets today, I really can't tell what the actual signal
strength of a particular station is anymore. It used to be so easy. I
would
connect up my old Sadelco analog meter to a cable or antenna coax and
simply read the carrier level. Now that we have two different types of
TV
broadcasting systems to deal with all my equipment is obsolete.
So I have two questions to pose to the group:
1. Has anyone noted consistent instances where one tuner is noticeably
"hotter" than the other? That is to say one set that will perform with
a
weak signal where the next being fed the same signal might break up?
This
slight difference in the front ends, which might never be detected on
cable
could affect antenna users in fringe areas like myself. In fact I
don't
know if I ever would have noticed this if I hadn't been running two
different sets in the shop at the same time).
2. If it's economically feasible I would like to be able to read
signal
level directly on a test instrument. This would be useful on antenna
jobs
as well as cable distribution systems. Is there such an affordable
instrument available for this purpose? Thanks, Lenny


I didn't figger out from your post where you're located. *Makes a
difference.
Here in the good ole USA, OTA HDTV sucks. *Encoding was picked by
lobbyists, not engineers.

I'm only 10 miles from the transmitters, but there's a hill in the middle
and a two-story metal pole building in my neighbor's yard. *It's
multipath city here. *Ability to decode a channel also depends
on the season and how many leaves the intermediate trees have.

I have a combo VHF/UHF antenna on a rotor, but if you wanna record more
than one thing at a time, you can't be turning the antenna.

The Zenith DTT901's work pretty well, unless it's raining hard, but
the output isn't HD.

I have several older cable boxes that work on some channels.
It's particularly annoying on some boxes that there's no way to
add channels. *If you need a different antenna direction to detect
a channel, you can't find all the channels with the auto scan.

The ATSC tuner card in the PC works the worst.
And it's not signal strength.
I put a variable attenuator in the antenna line and tweak it per channel
for fewest dropouts.

Before the big switch, when most of the ATSC channels were on UHF, signals
were much better. *After the switch, when they went back to VHF ATSC,
it got much worse.

I put the signal on a spectrum analyzer. *There's no correlation between
signal strength and stability of the picture. *The "Bart's head" display
is supposed to be flat on top. *There is a correlation between the flatness
of the top and the stability of the picture.

I have a friend in the industry. *He won't disclose details, but he claims
that the math to de-multipath the signal exists. *But it takes more
computing horsepower than you can get into a cheapo set top box with current
technology.

I'm unwilling to spend much money on this. *The whole idea of free TV
is that it be FREE. *I'd much rather have NTSC quailty than "no signal"
scrolling across the screen of what I thought I'd taped.


It's nice to hear that finally from someone else, because personally I
couldn't give a rats ass about HD either. We watched snowy pictures
for years on UHF because that's all we could get. You can watch a
snowy picture but you can't deal with "now you see it and now you
don't". I have 25 year old sets here that produced a damn good picture
on NTSC and were never a "problem" for us to watch. However now thanks
to our brilliant government those stations are only a memory and we're
stuck with this flawed system for eternity now. Sorry for the rant but
it just ****es me off to no end. Lenny


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Default OTA tuner sensitivity

On Jan 1, 7:26*am, klem kedidelhopper
wrote:

It's nice to hear that finally from someone else, because

personally I
couldn't give a rats ass about HD either. We watched snowy pictures
for years on UHF because that's all we could get. You can watch a
snowy picture but you can't deal with "now you see it and now you
don't". I have 25 year old sets here that produced a damn good

picture
on NTSC and were never a "problem" for us to watch. However now

thanks
to our brilliant government those stations are only a memory and

we're
stuck with this flawed system for eternity now. Sorry for the rant

but
it just ****es me off to no end. Lenny


Happy New Year to you too.

I've been running OTA DTV since Dec 2003. It is possible for it to
work flawlessly but it can be tricky to get running. Signal strength
is secondary. Flat response is FAR more important (no ghost phase
cancellations). Unfortunately a spectrum analyzer is the best tool
ESPECIALLY if you're going to try to use reflections rather than line
of sight.

All ATSC receivers include equalizers to flatten the response. Early
receivers don't work as well as the newer ones and to say PC tuners
are universally bad is ignorant. Like the tuners built in TVs, the
newer ones are better in than they can tweak the equalization faster
meaning they're more tolerant of the trees blowing in front of your
path. Known GOOD PC tuners are made by Hauppauge. I have 2 ATI HDTV
Wonder PC tuners which never break up and 1 Hauppauge 1250 tuner that
also never breaks up BUT I also have a properly installed antenna
system that has known flat response. You can get an idea of how good
your tuner and antenna is by how fast you can change a channel and
achieve lock. The flatter the response, the less action is needed by
the equalizer.

One of the reasons the 8VSB was selected was that it requires less
power than COFDM. If you check complaints in countries with COFDM you
find them similar to yours.

The first spectrum analyzer photo is AWEFUL and is likely beyond the
capabilities of any tuner. The second is what it should be.

http://www.prism.gatech.edu/~wn17/

G
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Default OTA tuner sensitivity

On Jan 1, 12:05*pm, wrote:
On Jan 1, 7:26*am, klem kedidelhopper
wrote:

* It's nice to hear that finally from someone else, because
personally I
* couldn't give a rats ass about HD either. We watched snowy pictures
* for years on UHF because that's all we could get. You can watch a
* snowy picture but you can't deal with "now you see it and now you
* don't". I have 25 year old sets here that produced a damn good
picture
* on NTSC and were never a "problem" for us to watch. However now
thanks
* to our brilliant government those stations are only a memory and
we're
* stuck with this flawed system for eternity now. Sorry for the rant
but
* it just ****es me off to no end. Lenny

Happy New Year to you too.

I've been running OTA DTV since Dec 2003. It is possible for it to
work flawlessly but it can be tricky to get running. Signal strength
is secondary. Flat response is FAR more important (no ghost phase
cancellations). Unfortunately a spectrum analyzer is the best tool
ESPECIALLY if you're going to try to use reflections rather than line
of sight.

All ATSC receivers include equalizers to flatten the response. Early
receivers don't work as well as the newer ones and to say PC tuners
are universally bad is ignorant. Like the tuners built in TVs, the
newer ones are better in than they can tweak the equalization faster
meaning they're more tolerant of the trees blowing in front of your
path. Known GOOD PC tuners are made by Hauppauge. I have 2 ATI HDTV
Wonder PC tuners which never break up and 1 Hauppauge 1250 tuner that
also never breaks up BUT I also have a properly installed antenna
system that has known flat response. You can get an idea of how good
your tuner and antenna is by how fast you can change a channel and
achieve lock. The flatter the response, the less action is needed by
the equalizer.

One of the reasons the 8VSB was selected was that it requires less
power than COFDM. If you check complaints in countries with COFDM you
find them similar to yours.

The first spectrum analyzer photo is AWEFUL and is likely beyond the
capabilities of any tuner. The second is what it should be.

http://www.prism.gatech.edu/~wn17/

G


That is a very interesting idea. Thanks for the pictures. But I'm just
curious though, is there any reason for using the screen (except for
cost that is) as opposed to say sheet copper or even in the case of a
prototype, aluminum foil? What about any detuning of the antenna that
might occur when placing ground in close proximity with the antenna? I
had to relocate the mast on a 75 MHZ antenna some time ago and needed
to install 5 ft. of fiberglass mast so as not to detune the antenna's
driven element. How did you determine that this would work? Is this
increasing the "Q" or is it just functioning as a shield? Lenny
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On Sun, 1 Jan 2012 11:44:45 -0800 (PST), klem kedidelhopper
wrote:

http://www.prism.gatech.edu/~wn17/


That is a very interesting idea. Thanks for the pictures.


Nice idea. Basically, it's a 600MHz waveguide, with a yagi inside.
Something like a horn antenna. It should work for frequencies about
600MHz, but won't do much for the lower UHF channels. The main thing
that it does is block the side lobes, which are where the reflections
are probably coming from.

The author thinks the multipath is coming from the buildings in the
distance. I disagree as my guess(tm) of the increased path length is
insufficient to cause cancellation (frequency selective fading). The
wire screen horn won't do much for eliminating reflections from
something that's almost straight ahead anyway.

What the wire screen horn does do is block reflections from the side
and most important, from the back. However, my guess(tm) is that the
multipath is coming from BEHIND the antenna, not in front. It's
really easy to test where it's coming from if you get near the
antenna. Take a sheet of anti-static IC foam (mostly carbon), or a
wet towel, and move it around the antenna. When the ghosts disappear,
that's the direction of the reflection. The idea behind the foam and
wet towel is that you want an absorber, rather than a reflector. That
would also apply to the horn construction. Instead of wire screen
(reflector), it really should be made of something that absorbs RF.

But I'm just
curious though, is there any reason for using the screen (except for
cost that is) as opposed to say sheet copper or even in the case of a
prototype, aluminum foil?


It will work the same with solid metal. You could use aluminum foil
on box cardboard as long as all the edges are connected. If you're
lazy, shove the antenna into a 55 gallon drum.

What about any detuning of the antenna that
might occur when placing ground in close proximity with the antenna?


Detuning will probably be severe. I can do an NEC2 model to see how
bad, but I couldn't find an antenna model close enough to clone:
http://www.hdtvprimer.com/ANTENNAS/comparing.html
I'm at home with a cold or flu. Thinking hurts. Another time.

I
had to relocate the mast on a 75 MHZ antenna some time ago and needed
to install 5 ft. of fiberglass mast so as not to detune the antenna's
driven element.


What about the feed line? If the 75MHz antenna is horizontally
polarized, and you run the coax down the boom, and then down the
fiberglass mast, you may have problems. You'll have fewer problems if
the antenna has a balun to keep the coax from radiating. The only way
you can keep the feed line out of the pattern with a yagi is to
cantilever mount the antenna by the boom behind the reflector, and run
the coax down the boom.

How did you determine that this would work? Is this
increasing the "Q" or is it just functioning as a shield? Lenny


Shield.

--
Jeff Liebermann
150 Felker St #D
http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
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wrote:
On Jan 1, 7:26 am, klem kedidelhopper
wrote:

It's nice to hear that finally from someone else, because

personally I
couldn't give a rats ass about HD either. We watched snowy pictures
for years on UHF because that's all we could get. You can watch a
snowy picture but you can't deal with "now you see it and now you
don't". I have 25 year old sets here that produced a damn good

picture
on NTSC and were never a "problem" for us to watch. However now

thanks
to our brilliant government those stations are only a memory and

we're
stuck with this flawed system for eternity now. Sorry for the rant

but
it just ****es me off to no end. Lenny


Happy New Year to you too.

I've been running OTA DTV since Dec 2003. It is possible for it to
work flawlessly but it can be tricky to get running. Signal strength
is secondary. Flat response is FAR more important (no ghost phase
cancellations). Unfortunately a spectrum analyzer is the best tool
ESPECIALLY if you're going to try to use reflections rather than line
of sight.

All ATSC receivers include equalizers to flatten the response. Early
receivers don't work as well as the newer ones and to say PC tuners
are universally bad is ignorant. Like the tuners built in TVs, the
newer ones are better in than they can tweak the equalization faster
meaning they're more tolerant of the trees blowing in front of your
path. Known GOOD PC tuners are made by Hauppauge. I have 2 ATI HDTV
Wonder PC tuners which never break up and 1 Hauppauge 1250 tuner that
also never breaks up BUT I also have a properly installed antenna
system that has known flat response. You can get an idea of how good
your tuner and antenna is by how fast you can change a channel and
achieve lock. The flatter the response, the less action is needed by
the equalizer.

One of the reasons the 8VSB was selected was that it requires less
power than COFDM. If you check complaints in countries with COFDM you
find them similar to yours.

The first spectrum analyzer photo is AWEFUL and is likely beyond the
capabilities of any tuner. The second is what it should be.

http://www.prism.gatech.edu/~wn17/

G

Great job fixing the flatness.
My problems are mostly on VHF 2,6,8.
And there's a few degrees difference in the direction to the different
channels that adds to the problems. Sometimes, I tape three channels
at once, so turning the antenna for each one is not an option.

My PC tuner is an ATI HDTV Wonder also. It's the worst one I have.

What software do you use with the HDTV wonder?
My CPU is only 2.8GHz and I had insufficient horsepower to run any of the
M$ stuff.
WatchHDTV is the only free program I found that worked at all. Has a
lot of studdering on VHF when conditions are not perfect. I get better
reception when I REDUCE the signal level with a passive attenuator.

And it has a weird problem. If the computer goes to sleep, I can never
get the TV to work again. Rebooting doesn't help, but totally powering
the system off brings back the TV.
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Default OTA tuner sensitivity

On Sun, 1 Jan 2012 07:26:10 -0800 (PST), klem kedidelhopper
wrote:

On Jan 1, 5:00*am, mike wrote:
klem kedidelhopper wrote:
I made an interesting observation today and thought that I would
relate it
to the group. I use a set top converter in the shop to receive OTA
signals
from my antenna. I just put up the antenna this past Fall so I don't
have
much history with this particular antenna. However I can say without
hesitation that for the past 33 years at this same location as soon as
the
leaves start to come out in the Spring, our UHF reception would begin
to
degrade. We are in a deep fringe area so UHF reception has always been
boarder line on many channels. Obviously digital has made that
situation
even more difficult for us. With the new installation though, an old
Channel Master parabolic that I resurrected, with a Winegard GA8780
preamp,
things have improved quite a bit over the old Yagi we had been using.


So today I just finished up a three year old Samsung and auto
programmed it
off my antenna. I noted many more channels than my bench converter had
previously picked up and stored. So then I went to the converter and
manually entered the new channels. To my surprise I did get most, but
not
all of the new ones. So perhaps propagation has changed somewhat. I
don't
know. In any case there is definitely a difference in front ends on
these
two receivers.


There was this one channel in particular that looked fine on the
Samsung
but would intermittently very lightly "pixelate" when processed
through my
set top converter. I removed the 2 way splitter feeding the bench and
the
set and fed the bench directly thereby increasing the level to the
bench by
3DB. The weak channel was improved but still would break up, (but less
pronounced) on occasion.


What frustrates me is that except for the OSD "bar graph" signal
indicators
on most digital sets today, I really can't tell what the actual signal
strength of a particular station is anymore. It used to be so easy. I
would
connect up my old Sadelco analog meter to a cable or antenna coax and
simply read the carrier level. Now that we have two different types of
TV
broadcasting systems to deal with all my equipment is obsolete.
So I have two questions to pose to the group:
1. Has anyone noted consistent instances where one tuner is noticeably
"hotter" than the other? That is to say one set that will perform with
a
weak signal where the next being fed the same signal might break up?
This
slight difference in the front ends, which might never be detected on
cable
could affect antenna users in fringe areas like myself. In fact I
don't
know if I ever would have noticed this if I hadn't been running two
different sets in the shop at the same time).
2. If it's economically feasible I would like to be able to read
signal
level directly on a test instrument. This would be useful on antenna
jobs
as well as cable distribution systems. Is there such an affordable
instrument available for this purpose? Thanks, Lenny


I didn't figger out from your post where you're located. *Makes a
difference.
Here in the good ole USA, OTA HDTV sucks. *Encoding was picked by
lobbyists, not engineers.

I'm only 10 miles from the transmitters, but there's a hill in the middle
and a two-story metal pole building in my neighbor's yard. *It's
multipath city here. *Ability to decode a channel also depends
on the season and how many leaves the intermediate trees have.

I have a combo VHF/UHF antenna on a rotor, but if you wanna record more
than one thing at a time, you can't be turning the antenna.

The Zenith DTT901's work pretty well, unless it's raining hard, but
the output isn't HD.

I have several older cable boxes that work on some channels.
It's particularly annoying on some boxes that there's no way to
add channels. *If you need a different antenna direction to detect
a channel, you can't find all the channels with the auto scan.

The ATSC tuner card in the PC works the worst.
And it's not signal strength.
I put a variable attenuator in the antenna line and tweak it per channel
for fewest dropouts.

Before the big switch, when most of the ATSC channels were on UHF, signals
were much better. *After the switch, when they went back to VHF ATSC,
it got much worse.

I put the signal on a spectrum analyzer. *There's no correlation between
signal strength and stability of the picture. *The "Bart's head" display
is supposed to be flat on top. *There is a correlation between the flatness
of the top and the stability of the picture.

I have a friend in the industry. *He won't disclose details, but he claims
that the math to de-multipath the signal exists. *But it takes more
computing horsepower than you can get into a cheapo set top box with current
technology.

I'm unwilling to spend much money on this. *The whole idea of free TV
is that it be FREE. *I'd much rather have NTSC quailty than "no signal"
scrolling across the screen of what I thought I'd taped.


It's nice to hear that finally from someone else, because personally I
couldn't give a rats ass about HD either. We watched snowy pictures
for years on UHF because that's all we could get. You can watch a
snowy picture but you can't deal with "now you see it and now you
don't". I have 25 year old sets here that produced a damn good picture
on NTSC and were never a "problem" for us to watch. However now thanks
to our brilliant government those stations are only a memory and we're
stuck with this flawed system for eternity now. Sorry for the rant but
it just ****es me off to no end. Lenny



Add my vote. Damned lobbyists. Damned tomfool government legislutors.

?-)


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Default OTA tuner sensitivity

On Jan 1, 3:07*pm, mike wrote:

Great job fixing the flatness.
My problems are mostly on VHF 2,6,8.
And there's a few degrees difference in the direction to the

different
channels that adds to the problems. *Sometimes, I tape three

channels
at once, so turning the antenna for each one is not an option.

My PC tuner is an ATI HDTV Wonder also. *It's the worst one I have.

What software do you use with the HDTV wonder?
My CPU is only 2.8GHz and I had insufficient horsepower to run any

of the
M$ stuff.
WatchHDTV is the only free program I found that worked at all. *Has

a
lot of studdering on VHF when conditions are not perfect. *I get

better
reception when I REDUCE the signal level with a passive attenuator.

And it has a weird problem. *If the computer goes to sleep, I can

never
get the TV to work again. *Rebooting doesn't help, but totally

powering
the system off brings back the TV.


You really have DTV on 2, 6 and 8? I checked this list and found only
6 channel 2 DTVs in the entire country.

http://www.dtv.gov/stationlist.htm

The first DVR PC I used was an AMD Sempron on a cheap ECS mobo wit 512
megs RAM and an ATI 9200 video card. The ATI software needed 20-40%
CPU and would stutter if surfing the web while it was recording. The
later Gigabyte 780 series boards with AMD Phenom II quad core
processors never stutter and can watch an HD recording while recording
another HD AND play out another HD stream across the LAN to another
PC. 2 machines have ATI HDTV Wonders ( I have 2 more machines off line
that have Wonders also). All machines run Win XP Pro SP3. The ATI
software is MMC 9.14 which has quirks but rarely screws up. The 3rd
machine has a Hauppauge 1250 tuner. None of the machines stutters but
the Hauppauge can handle dynamic ghosting better than the ATIs back
when I had antenna issues a few years back. The Hauppauge machine uses
WinTV v6 as the recording software and it too rarely screws up.
Commercials are removed with VideoReDo. All the machines are shut down
cold every night. The monitors and disk drives are never shut down
during the day. All have 1.5T drives and secondary drives as well, 1
500GB, 1 1T and 1 2T for a total of 8T spinning between 3 machines
with another 8T of USB drives.

We live in zip 90274 about 35 miles from Mt. Wilson and run a Winegard
SquareShooter on the roof for the UHF channels. The VHF (7, 9, 11, 13)
are picked up with a Winegard 7082 (20 yrs old but only 1 year
outdoors) in the rafters of the garage about 8 ft lower than the roof
antenna. They're combined with a UHF / VHF splitter running backwards
as a diplexer (combiner) and no preamps with the feed split 4 ways.
Channel 7 reports 66% on the ATI tuners. All other channels are 80-90%
The Hauppauge tuner reports S/N ratio. Ch 7 comes in at 25dB+ and the
rest max out at 30dB. For DTV at least 15dB S/N is required.

For most areas of the country the Winegard HD7694 would be an
excellent choice. Good gain and front/back ratio and directivity and
not big BUT it's no good for ch2-6 (actual digital channels, NOT
virtual channels) and FM.

http://www.winegard.com/kbase/upload/HD7694P.pdf

If you need ch 2-6 and.or FM this will do well but its BIG. It's
basically the specs of the 7694 but with low band VHF. The thing about
these guys is that they get their engineering right and don't make
outlandish claims. They just WORK.

http://www.winegard.com/kbase/upload/HD7084P.pdf

Excessive signal strength can cause overload issues but it's also
possible that the in line attenuator improves the termination of the
line and reduces reflections (same as multipath) in the transmission
line. The antenna itself and transmission line (connector
installation) can cause this as well. After reading on other groups I
switched to Snap n Seal connectors and outdoors under weather boots I
use clear heat sink grease (GC 10-8101) on the cable end to keep
oxygen out of the connector. I dissembled a connector 15 years old
with that treatment and it looked new inside. Pay attention to the
details and you won't have big issues.

Did you notice page 2 of the Georgia Tech antenna? It's even better
than page 1. I've wondered if you could use a wire basket instead of a
trash can to reduce wind loading.

G
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