Before the advent of mandatory digital over-the-air TV, it was said
that the picture would be near perfect, and that there woudl be no
ghosts. Tonight I saw one, for a full half hour if the scene had the
right kind of lines, including vertical lines.

From the beginning I had doubts about the claim there would be no
ghosts. I gleaned or understood that, aiui, if a ghost signal was
less than, say, 50% as strong as the direct signal, and the direct
signal were 0, the electronics would "round down" and output a zero.
If the direct signal were 1 and the ghost was less than 0.5 and more
than zero, or more than -0.5 and less than zero, the sum might be 1.5,
but the electronics would interpret that as a 1.

But that didn't account for every situation. What if the ghost signal
was 0.6 the strength of the direct signal and the direct signal was a
zero? Now, although I've never seen it discussed (and I do read a
bit) I presume there are 3 signals making up the OTA video signal, and
I'm ignoring that for now.

Anyhow, for the first time in 9 months, with no changes to the tv
wiring of my house, tonight I saw a ghost on an OTA tv show. On
channel 7.3 in Wash. DC, and I live about 30 or 40 miles north of the
transmitter. A black and white show, The Rifleman, with Chuck
Connors, from the 60's I think, but maybe the 50's.

I don't know from where the reflection could be coming. There is a 7
story building about 100 yards behind me and to the left (wrt channel
7) but that's not far enough away, is it, to account for 1/8" or 3/16"
ghost displacement on a 19" tv? Woudln't any ghost from there be a
small fraction of a millimeter from the main image?

Could the ghost be in the coaxial connection between my TV tuner (a
DVDR) and the tv. There is 15 feet of co=ax, an RF amp/splitter, 8
more feet of co-ax, a splitter, another RF amp, another splitter, 30
feet of co-ax, then another splitter, then 10 more feet of co-ax. If
that were the source, it wouldn't be attributable to a digital signal,
but I don't think those lengths are sufficient to account for a ghost
1/8" from the main image, are they?



They also didnt' mention, said otherwise though I forget the words
they used, that there would be checkerboard interference. I get that
a lot on several stations, especially the ones that are 30 or 40 miles
away.

How much tv did these people watch before they made their false
claims? Were they only a mile from the transmitter in rural Kansas?

Does anyone know their names or email addresses so i could tell them
how foolish they look?

I get two new stations I like with digital, so I'm not angry. (I
wouldn't be anyhow.) I just think they make themselves look stupid
when they make false claims that they should have known better than to
make, and to an extent, the impression this leaves spills over on to
other "experts" and "scientists", in other fields.

mm wrote:
Before the advent of mandatory digital over-the-air TV, it was said
that the picture would be near perfect, and that there woudl be no
ghosts. Tonight I saw one, for a full half hour if the scene had the
right kind of lines, including vertical lines.

From the beginning I had doubts about the claim there would be no
ghosts. I gleaned or understood that, aiui, if a ghost signal was
less than, say, 50% as strong as the direct signal, and the direct
signal were 0, the electronics would "round down" and output a zero.
If the direct signal were 1 and the ghost was less than 0.5 and more
than zero, or more than -0.5 and less than zero, the sum might be 1.5,
but the electronics would interpret that as a 1.

But that didn't account for every situation. What if the ghost signal
was 0.6 the strength of the direct signal and the direct signal was a
zero? Now, although I've never seen it discussed (and I do read a
bit) I presume there are 3 signals making up the OTA video signal, and
I'm ignoring that for now.

It doesn't matter what the relationship is between the main signal and
any reflected signals, they still won't cause ghosting in digital TV.
They may mess the signal up to the point where the television doesn't
produce a picture, but you won't get ghosting - digital TV simply
doesn't work that way.

Sylvia.

On Wed, 20 Jan 2010 18:25:14 +1100, Sylvia Else
wrote:

mm wrote:
Before the advent of mandatory digital over-the-air TV, it was said
that the picture would be near perfect, and that there woudl be no
ghosts. Tonight I saw one, for a full half hour if the scene had the
right kind of lines, including vertical lines.

From the beginning I had doubts about the claim there would be no
ghosts. I gleaned or understood that, aiui, if a ghost signal was
less than, say, 50% as strong as the direct signal, and the direct
signal were 0, the electronics would "round down" and output a zero.
If the direct signal were 1 and the ghost was less than 0.5 and more
than zero, or more than -0.5 and less than zero, the sum might be 1.5,
but the electronics would interpret that as a 1.

But that didn't account for every situation. What if the ghost signal
was 0.6 the strength of the direct signal and the direct signal was a
zero? Now, although I've never seen it discussed (and I do read a
bit) I presume there are 3 signals making up the OTA video signal, and
I'm ignoring that for now.

It doesn't matter what the relationship is between the main signal and
any reflected signals, they still won't cause ghosting in digital TV.
They may mess the signal up to the point where the television doesn't
produce a picture, but you won't get ghosting

But I did get ghosting.

- digital TV simply
doesn't work that way.

Who am I going to believe, your theory-based answer, or my own eyes?

Do you watch OTA tv these days?

Maybe it matters that the station is 30 or 40 miles away. Do you watch
stations like that?

Sylvia.

I also saw what was probably ghosting during a commercial right after
that show. The commercial had big thick red letters against a white
background, and the red continued about an eighth or three sixteenths
of an inch to the right, lighter than the main red image.

mm wrote:
On Wed, 20 Jan 2010 18:25:14 +1100, Sylvia Else
wrote:

mm wrote:
Before the advent of mandatory digital over-the-air TV, it was said
that the picture would be near perfect, and that there woudl be no
ghosts. Tonight I saw one, for a full half hour if the scene had the
right kind of lines, including vertical lines.

From the beginning I had doubts about the claim there would be no
ghosts. I gleaned or understood that, aiui, if a ghost signal was
less than, say, 50% as strong as the direct signal, and the direct
signal were 0, the electronics would "round down" and output a zero.
If the direct signal were 1 and the ghost was less than 0.5 and more
than zero, or more than -0.5 and less than zero, the sum might be 1.5,
but the electronics would interpret that as a 1.

But that didn't account for every situation. What if the ghost signal
was 0.6 the strength of the direct signal and the direct signal was a
zero? Now, although I've never seen it discussed (and I do read a
bit) I presume there are 3 signals making up the OTA video signal, and
I'm ignoring that for now.
It doesn't matter what the relationship is between the main signal and
any reflected signals, they still won't cause ghosting in digital TV.
They may mess the signal up to the point where the television doesn't
produce a picture, but you won't get ghosting

But I did get ghosting.

- digital TV simply
doesn't work that way.

Who am I going to believe, your theory-based answer, or my own eyes?

They are not necessarily inconsistent. You may have seen something, but
it wasn't ghosting, in the sense that it wasn't caused by your antenna
receiving a main signal and some delayed reflections.


Do you watch OTA tv these days?

Maybe it matters that the station is 30 or 40 miles away. Do you watch
stations like that?

Sylvia.

I also saw what was probably ghosting during a commercial right after
that show. The commercial had big thick red letters against a white
background, and the red continued about an eighth or three sixteenths
of an inch to the right, lighter than the main red image.



If you're using a set-top-box and feeding a composite video signal into
a conventional TV, you may just be seeing an effect where abrupt changes
in luminance feed into the colour signal.

Sylvia.

On Wed, 20 Jan 2010 19:53:33 +1100, Sylvia Else
wrote:

mm wrote:
On Wed, 20 Jan 2010 18:25:14 +1100, Sylvia Else
wrote:

mm wrote:
Before the advent of mandatory digital over-the-air TV, it was said
that the picture would be near perfect, and that there woudl be no
ghosts. Tonight I saw one, for a full half hour if the scene had the
right kind of lines, including vertical lines.

From the beginning I had doubts about the claim there would be no
ghosts. I gleaned or understood that, aiui, if a ghost signal was
less than, say, 50% as strong as the direct signal, and the direct
signal were 0, the electronics would "round down" and output a zero.
If the direct signal were 1 and the ghost was less than 0.5 and more
than zero, or more than -0.5 and less than zero, the sum might be 1.5,
but the electronics would interpret that as a 1.

But that didn't account for every situation. What if the ghost signal
was 0.6 the strength of the direct signal and the direct signal was a
zero? Now, although I've never seen it discussed (and I do read a
bit) I presume there are 3 signals making up the OTA video signal, and
I'm ignoring that for now.
It doesn't matter what the relationship is between the main signal and
any reflected signals, they still won't cause ghosting in digital TV.
They may mess the signal up to the point where the television doesn't
produce a picture, but you won't get ghosting

But I did get ghosting.

- digital TV simply
doesn't work that way.

Who am I going to believe, your theory-based answer, or my own eyes?

They are not necessarily inconsistent. You may have seen something, but
it wasn't ghosting, in the sense that it wasn't caused by your antenna
receiving a main signal and some delayed reflections.


Do you watch OTA tv these days?

Maybe it matters that the station is 30 or 40 miles away. Do you watch
stations like that?

Sylvia.

I also saw what was probably ghosting during a commercial right after
that show. The commercial had big thick red letters against a white
background, and the red continued about an eighth or three sixteenths
of an inch to the right, lighter than the main red image.



If you're using a set-top-box and feeding a composite video signal into
a conventional TV, you may just be seeing an effect where abrupt changes
in luminance feed into the colour signal.

No. I'm using a DVDR with a hard drive and a digital tuner and
sending an RF signal on channel 3 to an analog tv.

Isn't that what people with digital cable and satellite do if they
don't have composite or component inputs on their tvs?

Assuming for the sake of this paragraph that this makes a difference,
those many people who promoted the high quality of digital tv never
said anthing about this making a difference.

Sylvia.

mm wrote in message
news
On Wed, 20 Jan 2010 19:53:33 +1100, Sylvia Else
wrote:

mm wrote:
On Wed, 20 Jan 2010 18:25:14 +1100, Sylvia Else
wrote:

mm wrote:
Before the advent of mandatory digital over-the-air TV, it was said
that the picture would be near perfect, and that there woudl be no
ghosts. Tonight I saw one, for a full half hour if the scene had
the
right kind of lines, including vertical lines.

From the beginning I had doubts about the claim there would be no
ghosts. I gleaned or understood that, aiui, if a ghost signal was
less than, say, 50% as strong as the direct signal, and the direct
signal were 0, the electronics would "round down" and output a zero.
If the direct signal were 1 and the ghost was less than 0.5 and more
than zero, or more than -0.5 and less than zero, the sum might be
1.5,
but the electronics would interpret that as a 1.

But that didn't account for every situation. What if the ghost
signal
was 0.6 the strength of the direct signal and the direct signal was a
zero? Now, although I've never seen it discussed (and I do read a
bit) I presume there are 3 signals making up the OTA video signal,
and
I'm ignoring that for now.
It doesn't matter what the relationship is between the main signal and
any reflected signals, they still won't cause ghosting in digital TV.
They may mess the signal up to the point where the television doesn't
produce a picture, but you won't get ghosting

But I did get ghosting.

- digital TV simply
doesn't work that way.

Who am I going to believe, your theory-based answer, or my own eyes?

They are not necessarily inconsistent. You may have seen something, but
it wasn't ghosting, in the sense that it wasn't caused by your antenna
receiving a main signal and some delayed reflections.


Do you watch OTA tv these days?

Maybe it matters that the station is 30 or 40 miles away. Do you watch
stations like that?

Sylvia.

I also saw what was probably ghosting during a commercial right after
that show. The commercial had big thick red letters against a white
background, and the red continued about an eighth or three sixteenths
of an inch to the right, lighter than the main red image.



If you're using a set-top-box and feeding a composite video signal into
a conventional TV, you may just be seeing an effect where abrupt changes
in luminance feed into the colour signal.

No. I'm using a DVDR with a hard drive and a digital tuner and
sending an RF signal on channel 3 to an analog tv.

Isn't that what people with digital cable and satellite do if they
don't have composite or component inputs on their tvs?

Assuming for the sake of this paragraph that this makes a difference,
those many people who promoted the high quality of digital tv never
said anthing about this making a difference.

Sylvia.


So what you were seeing were fringes introduced in overdriven RF stages or
harmonics/sub-harmonics/beats within the IFs or combinations between

I would rather have ghosts instead of "no signal" blank screen and sound in
bad reception environment but unfortunately not an option these days

On Wed, 20 Jan 2010 10:31:09 -0000, "N_Cook"
wrote:

mm wrote in message
news
On Wed, 20 Jan 2010 19:53:33 +1100, Sylvia Else
wrote:

mm wrote:
On Wed, 20 Jan 2010 18:25:14 +1100, Sylvia Else
wrote:

mm wrote:
Before the advent of mandatory digital over-the-air TV, it was said
that the picture would be near perfect, and that there woudl be no
ghosts. Tonight I saw one, for a full half hour if the scene had
the
right kind of lines, including vertical lines.

From the beginning I had doubts about the claim there would be no
ghosts. I gleaned or understood that, aiui, if a ghost signal was
less than, say, 50% as strong as the direct signal, and the direct
signal were 0, the electronics would "round down" and output a zero.
If the direct signal were 1 and the ghost was less than 0.5 and more
than zero, or more than -0.5 and less than zero, the sum might be
1.5,
but the electronics would interpret that as a 1.

But that didn't account for every situation. What if the ghost
signal
was 0.6 the strength of the direct signal and the direct signal was a
zero? Now, although I've never seen it discussed (and I do read a
bit) I presume there are 3 signals making up the OTA video signal,
and
I'm ignoring that for now.
It doesn't matter what the relationship is between the main signal and
any reflected signals, they still won't cause ghosting in digital TV.
They may mess the signal up to the point where the television doesn't
produce a picture, but you won't get ghosting

But I did get ghosting.

- digital TV simply
doesn't work that way.

Who am I going to believe, your theory-based answer, or my own eyes?

They are not necessarily inconsistent. You may have seen something, but
it wasn't ghosting, in the sense that it wasn't caused by your antenna
receiving a main signal and some delayed reflections.


Do you watch OTA tv these days?

Maybe it matters that the station is 30 or 40 miles away. Do you watch
stations like that?

Sylvia.

I also saw what was probably ghosting during a commercial right after
that show. The commercial had big thick red letters against a white
background, and the red continued about an eighth or three sixteenths
of an inch to the right, lighter than the main red image.



If you're using a set-top-box and feeding a composite video signal into
a conventional TV, you may just be seeing an effect where abrupt changes
in luminance feed into the colour signal.

No. I'm using a DVDR with a hard drive and a digital tuner and
sending an RF signal on channel 3 to an analog tv.

Isn't that what people with digital cable and satellite do if they
don't have composite or component inputs on their tvs?

Assuming for the sake of this paragraph that this makes a difference,
those many people who promoted the high quality of digital tv never
said anthing about this making a difference.

Sylvia.


So what you were seeing were fringes introduced in overdriven RF stages or
harmonics/sub-harmonics/beats within the IFs or combinations between

Okay. But then I used the same system with analog tv transmission.
For 23 years I used a VCR and later for a year I used the DVDR using
its analog tuner, in both cases with RF output to this tv and other
tvs, all set on channel 3. Maybe the ghosts I saw then were also
fringes introduced in overdriven RF stages as you describe. ??

I would rather have ghosts instead of "no signal" blank screen and sound in
bad reception environment but unfortunately not an option these days

Me too. In fact picture quality has never mattered to me much (despite
this thread of mine about ghosts.) Much of the time I'm reading the
newspaper, cooking, or looking at the computer screen, and even when
I'm looking at the tv I don't care much. But even analog tvs in the
last several years have blanked out the screen and the sound if the
signal wasn't strong enough. It should have been an option. It should
still be an option.

On Wed, 20 Jan 2010 01:35:45 -0500, mm
wrote:

Before the advent of mandatory digital over-the-air TV, it was said
that the picture would be near perfect, and that there woudl be no
ghosts. Tonight I saw one, for a full half hour if the scene had the
right kind of lines, including vertical lines.

...

Please confirm that you do not drive a motor vehicle... If in fact you
do drive, please indicate what areas we should be on the watchout for
you.

PeterD wrote:
On Wed, 20 Jan 2010 01:35:45 -0500, mm
wrote:

Before the advent of mandatory digital over-the-air TV, it was said
that the picture would be near perfect, and that there woudl be no
ghosts. Tonight I saw one, for a full half hour if the scene had the
right kind of lines, including vertical lines.

...

Please confirm that you do not drive a motor vehicle... If in fact you
do drive, please indicate what areas we should be on the watchout for
you.

I missed the original post, but the appearance of ghosts can
be caused by a limited bandwidth of the video circuit.

Ghosts can also be caused by improper termination of the
feed line from the antenna to the TV.

root wrote:

Ghosts can also be caused by improper termination of the
feed line from the antenna to the TV.

On second thought, the digital processing should eliminate
any such effects on the RF side.

On second thought, the digital processing should
eliminate any such effects on the RF side.

I, too, am confused. A sufficiently strong ghost should garble the data to
the point where the image is corrupted -- not duplicated.

My guess is that the "ghosting" has some other source. It might even be in
the signal itself. If the low-pass video filter is not properly
phase-equalized, there can be severe ringing on the trailing edge of
objects, which would appear as "ghosts" of vertical lines.

Hi!

Before the advent of mandatory digital over-the-air TV, it was
said that the picture would be near perfect, and that there
would be no ghosts.

Ghosts in a digital over the air TV signal won't be caused for the
same reasons that analog over the air TV signals had them.

What's going out over the air in a digital TV transmission is a data
stream, complete with some degree of error correction. Any such
"ghosting" would show up in the signal as a duplicated datastream,
which is probably ignored or considered errant by the video
decompressor in the unit. If you were to get enough of these, you
might notice some glitching ("checkerboard pattern") in the video.

When you receive digital TV broadcasts, they will be an all or nothing
affair. Either you are receiving enough of the datastream to receive a
picture and sound, or you are not.

Tonight I saw one, for a full half hour if the scene had the
right kind of lines, including vertical lines.

The flaw could have been in the material being broadcast. No
broadcasting method can make up for flaws in the original material.
Older material is more likely to suffer from problems.

It sounds like you have a significant length of cable between your
converter box and TV set, going to a significant number of places and
through some amplifiers. If you are looking for interference, you are
looking there. But I don't think you'll find any--or at least not
much. In other words, this isn't the ideal situation, but I doubt it
is the problem.

Everything after the converter box's RF output is an analog TV signal
and therefore subject to the same things that can interfere with a
much more powerful analog TV broadcast signal.

The only major thing I don't like about digital TV is the
unwatchability of weak signals. Watching weak analog TV signals was
never much fun, but at least it was doable if you had to.

William

On Wed, 20 Jan 2010 06:21:44 -0800, "William Sommerwerck"
wrote:

On second thought, the digital processing should
eliminate any such effects on the RF side.

I, too, am confused. A sufficiently strong ghost should garble the data to
the point where the image is corrupted -- not duplicated.

My guess is that the "ghosting" has some other source. It might even be in
the signal itself. If the low-pass video filter is not properly
phase-equalized, there can be severe ringing on the trailing edge of
objects, which would appear as "ghosts" of vertical lines.

Is the trailing edge on the left side or the right side?

In article , mm wrote:
On Wed, 20 Jan 2010 18:25:14 +1100, Sylvia Else
wrote:

mm wrote:
Before the advent of mandatory digital over-the-air TV, it was said
that the picture would be near perfect, and that there woudl be no
ghosts. Tonight I saw one, for a full half hour if the scene had the
right kind of lines, including vertical lines.

From the beginning I had doubts about the claim there would be no
ghosts. I gleaned or understood that, aiui, if a ghost signal was
less than, say, 50% as strong as the direct signal, and the direct
signal were 0, the electronics would "round down" and output a zero.
If the direct signal were 1 and the ghost was less than 0.5 and more
than zero, or more than -0.5 and less than zero, the sum might be 1.5,
but the electronics would interpret that as a 1.

But that didn't account for every situation. What if the ghost signal
was 0.6 the strength of the direct signal and the direct signal was a
zero? Now, although I've never seen it discussed (and I do read a
bit) I presume there are 3 signals making up the OTA video signal, and
I'm ignoring that for now.

It doesn't matter what the relationship is between the main signal and
any reflected signals, they still won't cause ghosting in digital TV.
They may mess the signal up to the point where the television doesn't
produce a picture, but you won't get ghosting

But I did get ghosting.


You may be seeing spikes before and after due to filtering. It might be more
or only noticable viewing on an analog TV. I was seeing filtering
and emphasis effects on my 36 in CRT Toshiba on analog signals
which i assumed to be due to digital processing.


greg

- digital TV simply
doesn't work that way.

Who am I going to believe, your theory-based answer, or my own eyes?

Do you watch OTA tv these days?

Maybe it matters that the station is 30 or 40 miles away. Do you watch
stations like that?

Sylvia.

I also saw what was probably ghosting during a commercial right after
that show. The commercial had big thick red letters against a white
background, and the red continued about an eighth or three sixteenths
of an inch to the right, lighter than the main red image.

On 20/01/2010 06:35, mm wrote:
Before the advent of mandatory digital over-the-air TV, it was said
that the picture would be near perfect, and that there woudl be no
ghosts. Tonight I saw one, for a full half hour if the scene had the
right kind of lines, including vertical lines.

From the beginning I had doubts about the claim there would be no
ghosts.

Cabling signal crosstalk between multiple tuners at the baseband.

--
Adrian C

"William Sommerwerck" wrote in
:

On second thought, the digital processing should
eliminate any such effects on the RF side.

I, too, am confused. A sufficiently strong ghost should garble the
data to the point where the image is corrupted -- not duplicated.

My guess is that the "ghosting" has some other source. It might even
be in the signal itself. If the low-pass video filter is not properly
phase-equalized, there can be severe ringing on the trailing edge of
objects, which would appear as "ghosts" of vertical lines.




it could even be a coax cabling problem;some mismatch or cable defect,or
too long a cable from settop to TV.

OR the TV itself....
--
Jim Yanik
jyanik
at
localnet
dot com

mm wrote in message ...
Before the advent of mandatory digital over-the-air TV, it was said
that the picture would be near perfect, and that there woudl be no
ghosts. Tonight I saw one, for a full half hour if the scene had the
right kind of lines, including vertical lines.

From the beginning I had doubts about the claim there would be no
ghosts. I gleaned or understood that, aiui, if a ghost signal was
less than, say, 50% as strong as the direct signal, and the direct
signal were 0, the electronics would "round down" and output a zero.
If the direct signal were 1 and the ghost was less than 0.5 and more
than zero, or more than -0.5 and less than zero, the sum might be 1.5,
but the electronics would interpret that as a 1.

But that didn't account for every situation. What if the ghost signal
was 0.6 the strength of the direct signal and the direct signal was a
zero? Now, although I've never seen it discussed (and I do read a
bit) I presume there are 3 signals making up the OTA video signal, and
I'm ignoring that for now.

Anyhow, for the first time in 9 months, with no changes to the tv
wiring of my house, tonight I saw a ghost on an OTA tv show. On
channel 7.3 in Wash. DC, and I live about 30 or 40 miles north of the
transmitter. A black and white show, The Rifleman, with Chuck
Connors, from the 60's I think, but maybe the 50's.

I don't know from where the reflection could be coming. There is a 7
story building about 100 yards behind me and to the left (wrt channel
7) but that's not far enough away, is it, to account for 1/8" or 3/16"
ghost displacement on a 19" tv? Woudln't any ghost from there be a
small fraction of a millimeter from the main image?

Could the ghost be in the coaxial connection between my TV tuner (a
DVDR) and the tv. There is 15 feet of co=ax, an RF amp/splitter, 8
more feet of co-ax, a splitter, another RF amp, another splitter, 30
feet of co-ax, then another splitter, then 10 more feet of co-ax. If
that were the source, it wouldn't be attributable to a digital signal,
but I don't think those lengths are sufficient to account for a ghost
1/8" from the main image, are they?



They also didnt' mention, said otherwise though I forget the words
they used, that there would be checkerboard interference. I get that
a lot on several stations, especially the ones that are 30 or 40 miles
away.

How much tv did these people watch before they made their false
claims? Were they only a mile from the transmitter in rural Kansas?

Does anyone know their names or email addresses so i could tell them
how foolish they look?

I get two new stations I like with digital, so I'm not angry. (I
wouldn't be anyhow.) I just think they make themselves look stupid
when they make false claims that they should have known better than to
make, and to an extent, the impression this leaves spills over on to
other "experts" and "scientists", in other fields.

I've not had ghosting, but in the beginning of the transition, I used to get
something that looked like the reds were shifted, like bad convergence. The
shift changed, so that the red picture would sort of float around it's
target. It might have been a combination of the broadcasters working out the
bugs, and me working out the antenna, because my picture has been flawless
for about 6 months. I did cut way back on my signal level by removing a
distribution amp and padding the antenna output.

On Jan 20, 12:28*pm, "bg" wrote:
mm wrote in message ...
Before the advent of mandatory digital over-the-air TV, it was said
that the picture would be near perfect, and that there woudl be no
ghosts. * Tonight I saw one, for a full half hour if the scene had the
right kind of lines, including vertical lines.

From the beginning I had doubts about the claim there would be no
ghosts. *I gleaned or understood that, aiui, if a ghost signal was
less than, say, 50% as strong as the direct signal, and the direct
signal were 0, the electronics would "round down" and output a zero.
If the direct signal were 1 and the ghost was less than 0.5 and more
than zero, or more than -0.5 and less than zero, the sum might be 1.5,
but the electronics would interpret that as a 1.

But that didn't account for every situation. *What if the ghost signal
was 0.6 the strength of the direct signal and the direct signal was a
zero? *Now, although I've never seen it discussed (and I do read a
bit) I presume there are 3 signals making up the OTA video signal, and
I'm ignoring that for now.

Anyhow, for the first time in 9 months, with no changes to the tv
wiring of my house, tonight I saw a ghost on an OTA tv show. * On
channel 7.3 in Wash. DC, and I live about 30 or 40 miles north of the
transmitter. *A black and white show, The Rifleman, with Chuck
Connors, from the 60's I think, but maybe the 50's.

I don't know from where the reflection could be coming. *There is a 7
story building about 100 yards behind me and to the left (wrt channel
7) but that's not far enough away, is it, to account for 1/8" or 3/16"
ghost displacement on a 19" tv? * *Woudln't any ghost from there be a
small fraction of a millimeter from the main image?

Could the ghost be in the coaxial connection between my TV tuner (a
DVDR) and the tv. *There is 15 feet of co=ax, an RF amp/splitter, 8
more feet of co-ax, a splitter, another RF amp, another splitter, 30
feet of co-ax, then another splitter, then 10 more feet of co-ax. * If
that were the source, it wouldn't be attributable to a digital signal,
but I don't think those lengths are sufficient to account for a ghost
1/8" from the main image, are they?

They also didnt' mention, said otherwise though I forget the words
they used, that there would be checkerboard interference. *I get that
a lot on several stations, especially the ones that are 30 or 40 miles
away.

How much tv did these people watch before they made their false
claims? * Were they only a mile from the transmitter in rural Kansas?

Does anyone know their names or email addresses so i could tell them
how foolish they look?

I get two new stations I like with digital, so I'm not angry. (I
wouldn't be anyhow.) I just think they make themselves look stupid
when they make false claims that they should have known better than to
make, and to an extent, the impression this leaves spills over on to
other "experts" and "scientists", in other fields.

I've not had ghosting, but in the beginning of the transition, I used to get
something that looked like the reds were shifted, like bad convergence. The
shift changed, so that the red picture would sort of float around it's
target. It might have been a combination of the broadcasters working out the
bugs, and me working out the antenna, because my picture has been flawless
for about 6 months. I did cut way back on my signal level by removing a
distribution amp and padding the antenna output.- Hide quoted text -

- Show quoted text -

If it was a black and white picture, it could be there were some
artifacts caused by the film to video conversion. Did you check any
other sets or neighbors' tvs to see if they saw the same thing.

If it was a black and white picture, it could be there were some
artifacts caused by the film to video conversion. Did you check any
other sets or neighbors' tvs to see if they saw the same thing.

I had the same effect with two different brands of convertor boxes and on
different TV's. My antenna was common to both. I don't know if too much
signal could have caused it, or if it was broadcast with a problem. Most of
the local broadcasters did seem to need a month or two to get things right,
such as the sync between the video and audio, going off air etc ...
and I was tweaking the antenna quite often too, wondering if it was me or
them.

On Thu, 21 Jan 2010 00:21:06 -0700, "bg" wrote:


If it was a black and white picture, it could be there were some
artifacts caused by the film to video conversion. Did you check any
other sets or neighbors' tvs to see if they saw the same thing.

No. I figure I'll have a chance to do this later. To check this tv on
a different episode (Heck, I watched the show last night but forgot to
look.)

I had the same effect with two different brands of convertor boxes and on
different TV's. My antenna was common to both. I don't know if too much
signal could have caused it, or if it was broadcast with a problem. Most of
the local broadcasters did seem to need a month or two to get things right,
such as the sync between the video and audio, going off air etc ...

I've seen lack of sync but only once, I think, and not at the start.

and I was tweaking the antenna quite often too, wondering if it was me or
them.

I just got an antenna, but have to crawl into the attic to set it up.

On Jan 20, 2:31*am, "N_Cook" wrote:

So what you were seeing were fringes introduced in overdriven RF
stages or
harmonics/sub-harmonics/beats within the IFs or combinations
between

I would rather have ghosts instead of *"no signal" blank screen and
sound in
bad reception environment but unfortunately not an option these
days

Not how it works at all Nigel. Anything you're describing would
prevent proper demodulation of the data. With enough errors it would
fall off the 'cliff' and give no useful data. I don't doubt he saw
'ghosts' but they weren't RF multipath problems. I've been seeing a
bit more 'enhancement' artefacts on some HD signals which makes me a
little sad to see a good system get mis-used. OR, it may have been SD
material again 'enhanced' to cause the cartoon-like outlines. I have
seen some commercials that clearly (well, to me) came from a composite
source (likely a D2 machine) with decoding artefacts. Fortunately THAT
variety is fading away.

G²

On Jan 19, 10:35*pm, mm wrote:
Before the advent of mandatory digital over-the-air TV, it was said
that the picture would be near perfect, and that there woudl be no
ghosts. * Tonight I saw one, for a full half hour if the scene had the
right kind of lines, including vertical lines.

Digital broadcast TV doesn't support ghosts from transmission
artifacts. The link from DTV adapter to analog TV, or the
video amplifiers inside a vacuum-tube CRT television, can
support some kinds of ghost/ringing that might be perceptible.

Could the ghost be in the coaxial connection between my TV tuner (a
DVDR) and the tv. *There is 15 feet of co=ax, an RF amp/splitter, 8
more feet of co-ax, a splitter, another RF amp, another splitter, 30
feet of co-ax, then another splitter, then 10 more feet of co-ax.

But the important question is, is this connection from tuner
an analog NTSC (USA old TV standard) connection, or a digital ATSC
connection? Does your TV get this signal over channel 3, or is it
a digital channel, like 7.3, that it tunes? I presume it's
analog (i.e. your DVDR is converting ATSC input to NTSC output).

If it's really a poorly-terminated bunch of coaxial wiring, or even a
loose
connection somewhere in the coaxial knotwork, your sixty-feet
of wire can cause a resonance with circa 120 ns of delay (that's
a signal reflection doing the sixty feet of travel in round-trip
style).
Full screen-width, NTSC, is about 55 uS, so 120 ns is a couple of
percent
of the screen size. Whether that's consistent with '1/8 inch', I
can't say.

Reflections in wiring are caused by
(1) stub transmission lines - like splitters with long cables
connected
that DO NOT have a receiver attached. You can fix that by
disconnecting
long cables, or by putting a 75 ohm terminator on the unused end.
This applies to cables that are NOT part of the connection to your
target
television, as well as to the connecting channel; the echo from the
cable can be related to wiring to the spare bedroom. It all connects.
(2) loose connections. While watching the signal, adjust/loosen/
tighten
any and all connectors in the coaxial maze.
(3) faulty or overdriven amplifiers- For most use, a simple
splitter is better than
an amplifier; the signal/noise is not improved by amplification on the
OUTPUT of a tuner, you don't NEED any amplifier to drive a bit
of cable from that output. If the amplifier(s) cause signal
overload, or
support oscillation, they're a problem rather than a solution.

None of these reflection issues is related to the digital
transmission. It is
also possible that the TV has a weak video amplifier that has started
to
create dark shadows behind bright vertical lines because of aging
of the video amplifier's filter capacitors. Plug a video game into
the
TV and see if it has the same artifacts (if it does, it's TV repair
time).