TVs compatible, from one continent to the next??

[William Sommerwerck]

A DC synchronization aka "sync" pluse was included to
keep everything together so if signal got scrambled, the TV
would bring it back together quickly.

Actually, the sync pulses keep the horizontal and vertical scanning in the
receiver at the same frequency and phase as the transmitted signal.

Those rates were chosen because the studio lights were arc
lights and flashed on and off at the power line rate, so the TV
cameras had to be syncronized to them or you would get moving
black stripes across the screen.

This might have been a consideration, but the principal concern was "hum
bars" in the receiver. Modern power supplies are sufficiently well-filtered
that this isn't a concern.

The RCA system for compatible color TV (compatible with black
and white), used 1/4 of the color information based on the fact
that your eye only sees about that much.

Actually, it's more like 1/3.

The color information was encoded on a phase modulated 3.57MHz
subcarrier, which at the time was beyond the picture information, but
still within the transmitted signal.

Actually, it was within the picture (luminance) information. NTSC has always
had a potential video bandwidth of 4.2 MHz.

The original RCA system, alternated the phase of the carrier every line,
so that it would fix itself if there was a transmssion or syncrhonization
problem. To save money, the National Television Standards Commitee
(NTSC) which chose the standard, dropped the alternating phase.

Actually, it was dropped because it didn't seem possible at the time to
design a reasonably priced receiver that would take full advantage of this
feature (in particular, the elimnation of the Hue control). Also, the US
distribution system didn't have problems with non-linear phase, so PAL had
little practical advantage.

Also, the original proposal used red and blue color-difference signals,
rather than the more-efficient I and Q. The original NTSC proposal was
virtually identical to PAL. (If you don't believe this, I have a copy of
"Electronics" magazine that confirms it.)

The French used a different color encoding system called SECAM,
which was also based on the RCA system (1/4 color, 4.43mHz color
carrier) but designed to be totally incompatible so that you could not
watch French TV in England and vice versa.

SECAM stands for "sequential avec memoire".

SECAM was actually adopted because the French were idiots. They wanted a
system that was relatively easy to record on videotape. Unfortunately, it
made the receiver more-complex and expensive. A classic example of lousy
engineering.

 

[William Sommerwerck]

** Everyone knows that NTSC stands for:
"Never Twice the Same Color"

Though that might be the common opinion, it is, of course, untrue. There is
nothing inherently unstable or inaccurate about NTSC.

 

[William Sommerwerck]

The real problem was not that the NTSC system did not have
the autocorrection that was in the original design and used in
the PAL system. The real problem was that there was a knob
on the TV set that could make everything change color.

Actually, the real problem was that the networks didn't give a damn about
getting the color right.

This changed (I think) sometime in the late 70s. I've owned a number of
color TVs since then (want me to list them?), and don't remember even once
having touched the Hue control (incorrectly called the Tint control on most
sets).

It's significant, though, that if the average [censored] is given free hand
to adjust the Hue control, flesh tones almost always wind up on the green
side.

 

[William Sommerwerck]

** Most any TV set has internal adjustments for colour quality
as well as the usual external ones. However, each maker has
their own ideas of how to set the color balance (or color temp)
of a screen -- possibly to be technically accurate OR to look
" nice " to most viewers.

There are specific standards for color temperature and color accuracy. Any
"good" set should have a user selectable setting for 6500D. Many sets have
have essentially perfect primaries ("perfect" in that they meet the
standards). Most sets have slightly "off" tracking, however.

Left to my own devices, I tend to set the color temperature rather high --
9000K or so. This is perhaps because "noon daylight" looks yellow to me.

The principal problem is that the out-of-the-box settings almost always have
the brightness and contrast jacked way up, so the naive viewer will be
impressed. This is roughly equivalent to "the louder speaker sounds better".

 

[Phil Allison]

"William Sommerwanker is a Cunthead "

** Everyone knows that NTSC stands for:

"Never Twice the Same Color"

Though that might be the common opinion, it is, of course, untrue. There
is
nothing inherently unstable or inaccurate about NTSC.

** You have got to be the most ignorant wanker on the planet.




..... Phil

 

[Geoffrey S. Mendelson]

Dave Plowman (News) wrote:

But I don't think that's correct. For it to work, TV would have to be
mains locked. It was in the very early days, but later was pulse generator
locked with no direct reference to mains other than being nominally the
same frequency. Mains lock was really just to make receiver design simpler.

You sort of danced around it. In the very early days is when the frequency was
set. Once set it stayed.

That really was the point of my very long explanation. A long time ago someone
decided to fix the scan rate and representation of data. The actual information
used in all the TV systems was the same, it was just used with incompatable
frame rates, encoding systems and transmission systems mostly for politcal
reasons. TV sets that could receive, decode and play any and all signals
existed.

The reason that everyone did not have a universal TV set was because the price
was kept lower with single system sets and countries like the UK, which made
a substansial income from the TV license did not want you watching tv from
France or the Republic of Ireland for free.

From a technology point of view, it was obvious that the digitial TV standards
MPEG and so on were designed with existing TV sets in mind. If not they would
not have been a continuation of the old limited national standards with their
horrible color encoding choice (1/4 of the resolution that the monochrome
signal had) and instead gone with the more extensible, accurate and easily
compressable RGB system used in computer data.

Geoff.

--
Geoffrey S. Mendelson N3OWJ/4X1GM
Those who cannot remember the past are condemned to misquote it.

 

[William Sommerwerck]

** Everyone knows that NTSC stands for:
"Never Twice the Same Color"

Though that might be the common opinion, it is, of course,
untrue. There is nothing inherently unstable or inaccurate
about NTSC.

** You have got to be the most ignorant wanker on the planet.

When was the last time you adjusted the Hue control on an NTSC receiver?
That's not a rhetorical question.

 

[mm]

On Sat, 8 Jan 2011 04:58:32 -0800, "William Sommerwerck"
<grizzledgeezer@comcast.net> wrote:

Did they make digital TVs compatible from
the US to Europe to Asia to Australia, etc?

The following gives an indirect answer...

http://en.wikipedia.org/wiki/Digital_terrestrial_television

...which appears to be "no". There is no law of nature that prohibits a
multi-voltage, multi-standard receiver, but there is a law of economics --
there's little or no demand for one, as it would be useful only to people
who travelled a lot.

The reason I care is the opposite of that. There are only two
DVDR-with-harddrives for sale in the US, and one is cheaper than the
one I have, which itself is inferior in design. The other may be
better or not. However there are other models for sale in Australia,
and probably other parts of the world. I want to buy one from
Australia and use it here.

As for a single-inventory non-portable "universal" receiver... It would cost
more than a set that received only the local standard, so, again, you have
economics working against a multi-standard receiver.

What i had in mind wasn't** a multi-standard receiver but their
adopting one standard for the whole world, something they didnt' do
with B&W or color tv, for understandable reasons.

From reading the first few replies I guess the reason there is no
single standard now is so that the digital tv would play on analog
televisions, that making a set-top box or digital to analogue
converter which would also change frame rate was considered hard.

**OTOH, I am a broken DVD player that plays both NTSC and PAL dvds and
the girl who gave it to me said it cost 40 dollars. It even has a
button on the remote to change from NTSC to PAL and back. So the part
that handled the second format couldn't have been more than 5 dollars,
maybe 10, right? Maybe much less. Doesn't that mean it would cost
no more to include that in tvs?

(Strangely it does refer to needing matching regions, but gives no
indication on the box, on the player, or in the manual, what region it
is. My friend said it played the US and Europe and Japan, regions 1
and 2.

 

[Geoffrey S. Mendelson]

William Sommerwerck wrote:

SECAM was actually adopted because the French were idiots. They wanted a
system that was relatively easy to record on videotape. Unfortunately, it
made the receiver more-complex and expensive. A classic example of lousy
engineering.

The over the air signals were also spaced differently than PAL and instead
of FM audio like everyone else in the world, they used AM. So even if
you could maniptulate your TV tuner into picking up the video signal, and did
not mind watching it in black and white, there was no sound.

The rest of the world that did adopt SECAM used the PAL over the air
channel spacing and audio carriers, so that a PAL VCR could record/play the
signals with very little modification if any at all and a PAL TV could play
them in black and white, with audio.

The system was called MESECAM (Middle East Secam because many arab countries
adopted it). I think the Warsaw Pact countries, Soviet Union and China (PRC)
also did, but the Soviet VCRs ran at a different speed than the regular ones.

There was also NTSC 4.43, which was a 60Hz NTSC signal with the color subcarrier
at 4.43 mHz. It was developed as a cheap way of adding NTSC capability to
multisystem VCRs and TV sets, but was never broadcast over the air.

That's why I said that the OP must of either spent the last 30 years under
a rock or in the US. In the US no one cared, everything was NTSC or converted
to it for sale, while elsewhere in the world, everyone was trying to get
multisystem TV sets and VCRs.

You could buy them the US too, but only in stores that catered to foreigners,
visitors and sailors on leave.

Geoff.

--
Geoffrey S. Mendelson N3OWJ/4X1GM
Those who cannot remember the past are condemned to misquote it.

 

[mm]

On Sat, 08 Jan 2011 13:21:35 +0000 (GMT), "Dave Plowman (News)"
<dave@davenoise.co.uk> wrote:

In article <prestwhich-D23460.05094208012011@mx02.eternal-september.org>,
Smitty Two <prestwhich@earthlink.net> wrote:
The North and South American standard is NTSC, which transmits 30 frames
per second, while PAL, used in Europe, is 25 frames per second. The
switch to digital didn't affect that.

Digital is neither NTSC or PAL. Those are exclusively analogue. It rather
annoys that DVDs are labelled as NTSC and PAL when what they're referring
to is a region.

If that is the case, how is it possible I have a DVD that is PAL, but
all regions?


(I bought it by mistake, didn't notice the PAL, can't play it on my
DVD player**, but can on the computer. **The DVD player in the other
thread is broken.)

 

[mm]

On Sat, 8 Jan 2011 18:19:07 +0000 (UTC), "Geoffrey S. Mendelson"
<gsm@mendelson.com> wrote:

mm wrote:
For 60 years, USA tv signals and European ones, etc. were not
compatible.

Sort of. Multisystem TV's Were common in the 1980's. There were only 4 systems
of video, although there there were lots of ways to transmit them.

They were NTSC (60Hz, 3.57mHz color carrier), 50Hz PAL, 60Hz PAL, and 50Hz
SECAM. There also was 405 line UK TV (dropped in the early 1980's) and
NTSC 4.43 (same signal, color carrier moved to make cheaper playback equipment).

I still have a 1985 Sharp TV set that will play both NTSC versions, All PAL
versions, and SECAM from anywhere except France. I had a 14 system VCR that
would play and record French SECAM and a different TV set to play it on.

My kids use a 21 inch 4:3 CRT that is simialr, except that it does not
have a French tuner. It added component and S-video instead.

Did they make digital tvs compatible from the US to Europe to Asia to
Australia, etc?

I also have had VCRS that included digital TV standards converters. They
were multisystem VCRs with the conversion feature added on top.

But digital TV was not needed, analog TV's played the signals fine. It was
just a matter of adding the correct hardware.

I think they should have. If not, is it only the 50 versus 60
vertical scan rate that was the problem?

The color carrier. NTSC used a phase modulated color carrier at 3.5mHz. PAL
used a similar carrier at 4.43mHz.

But thoss were in the analog signals. When they went to digital, why
didn't they stop using PAL or stop using NTSC? That is my point.

What tied them to both PAL and ntsc at the same time?

Regional pride?

Or was it because they wanted current analog tvs to be able to receive
digital signals that went through a set-top digital to analog
converter, and some tvs wanted 50 cycle and others 60 cycle, so if the
air-borne signal was the same, it couldnt' be converted to one of 50
or 60?

To fix a problem noticed in NTSC signals
the BBC adopted the practice (which was in the proposed NTSC spec but
dropped to save money) of alternating the phase every other line, hence
the name PAL (Phase Alternating Line).

TV sets which would lock on 50Hz or 60Hz signals as appropriate were not
a technical issue and by 1980 almost all made would anyway.

SECAM used a different decoding method, but those chips were easily found,
and it was common to see TV sets and VCRS that would play/record SECAM signals
broadcast using PAL over the air standards. Eastern Europe (Warsaw Pact
countries), most Arab countires, China, and the USSR used some form of SECAM
encoded signals with PAL frequencies.

The French used a different channel spacing, and AM sound, which made
their SECAM signals impossible to tune with the correct tuner. It also made
Eastern European TVs worthless in France and vice versa.

I don't think I've read anything about this.

You either must have head your head under a rock, or live in the US and never
traveled out of there.

Please see my question higher up.

Note that I had several multisystem TV sets, VCRS (BETA and VHS), and even
a portable combination AM/FM/SW receiver and TV set that looked like a
Star Treck tri-corder, all puchased in the 1980's in Philly.

Geoff.

 

[Phil Allison]

"William Sommerwanker is a Cunt

** Everyone knows that NTSC stands for:

"Never Twice the Same Color"

Though that might be the common opinion, it is, of course,
untrue. There is nothing inherently unstable or inaccurate
about NTSC.

** You have got to be the most ignorant wanker on the planet.

When was the last time you adjusted the Hue control on an NTSC receiver?

** Go fuck yourself - asshole.

NTSC inherently suffers from sensitivity to phase shift in the sub carrier
during transmission and reception that cause colour changes on the screen -
particularly so when changing channel.

PAL does not.

Hence the famous acronym as quoted by me.

Go fuck yourself.


..... Phil

 

[Phil Allison]

"mm"

But thoss were in the analog signals. When they went to digital, why
didn't they stop using PAL or stop using NTSC? That is my point.

What tied them to both PAL and ntsc at the same time?

** The fact that folk ALL have TV sets and VCRs that work with those
standards ???

You trolling bloody IDIOT !!



...... Phil

 

[Geoffrey S. Mendelson]

mm wrote:

If that is the case, how is it possible I have a DVD that is PAL, but
all regions?

There are three possibilities of video encoded on DVDs. NTSC film (24/1001
frames per second), PAL (film and video 25 frames per second) and and NTSC
video 30/1001 frames per second.

The video encoding is based upon the source material.

Region encoding has absolutely nothing to do with the source material, it has
to do with encryption method to limit sales in various countries.

DVD players sold in the US will automatically play the video on the disk as
NTSC unless they use an HDMI output, where they will may just pass it and let
the TV set figure out how to play it or convert it anyway.

The same with DVD players sold in PAL countries, however most of them
have a setup option to either convert everything to PAL, convert it to NTSC,
or leave it the way it is for a multisystem TV.

Geoff.


--
Geoffrey S. Mendelson N3OWJ/4X1GM
Those who cannot remember the past are condemned to misquote it.

 

[Dave Plowman (News)]

In article <slrniij62b.ju.gsm@cable.mendelson.com>,
Geoffrey S. Mendelson <gsm@mendelson.com> wrote:

But I don't think that's correct. For it to work, TV would have to be
mains locked. It was in the very early days, but later was pulse
generator locked with no direct reference to mains other than being
nominally the same frequency. Mains lock was really just to make
receiver design simpler.

You sort of danced around it. In the very early days is when the
frequency was set. Once set it stayed.

Sadly not when locked to mains as that frequency drifts. By rather a lot
in electronic terms.

That really was the point of my very long explanation. A long time ago
someone decided to fix the scan rate and representation of data. The
actual information used in all the TV systems was the same, it was just
used with incompatable frame rates, encoding systems and transmission
systems mostly for politcal reasons. TV sets that could receive, decode
and play any and all signals existed.

I think you're reading in the political bit. Different countries had
settled on different mains frequencies rather before such things mattered
much.

The reason that everyone did not have a universal TV set was because the
price was kept lower with single system sets and countries like the UK,
which made a substansial income from the TV license did not want you
watching tv from France or the Republic of Ireland for free.

That is total nonsense. The TV licence is needed in the UK just to
operated a TV receiver - regardless of where the progs are transmitted
from. And they were single channel sets originally, because only the BBC
transmitted TV and only the one channel. Not many in the UK would have
been interested in French language broadcasts. ;-)

From a technology point of view, it was obvious that the digitial TV
standards MPEG and so on were designed with existing TV sets in mind. If
not they would not have been a continuation of the old limited national
standards with their horrible color encoding choice (1/4 of the
resolution that the monochrome signal had) and instead gone with the
more extensible, accurate and easily compressable RGB system used in
computer data.

Think you're well into hindsight. When the UK PAL system was finalised
(1960?), computers were some esoteric device in a lab. But in any case a
major priority of any colour TV system then was that it can be easily
receivable on a monochrome only set - and not make that set more expensive
to produce.

--
*There are two sides to every divorce: Yours and shit head's*

Dave Plowman dave@davenoise.co.uk London SW
To e-mail, change noise into sound.

 

[Geoffrey S. Mendelson]

mm wrote:

The reason I care is the opposite of that. There are only two
DVDR-with-harddrives for sale in the US, and one is cheaper than the
one I have, which itself is inferior in design. The other may be
better or not. However there are other models for sale in Australia,
and probably other parts of the world. I want to buy one from
Australia and use it here.

What exactly do you want? Here in Israel you can buy a DVB-T set top
box for 300 NIS ($75 US) with one having been on sale a few weeks ago for
99 NIS.

It has a USB port, but no storage, which allows you to plug in a disk drive
or USB memory stick, and record off the air. If your program provider uses
the EPG (electronic programing guide) material, you can use it to set the
device to record the programs.

The recordings are raw MPEG TS (transport streams) files. Which you can
use a PC to convert to something useful. You have to unplug the drive from
the unit and plug it into your PC, there is no PC to device connection.

I think the devices are single threaded, you can only watch one program,
or record one program, or play one recording at a time.

You can also buy a USB tuner stick for 99 NIS that plugs into a PC and
lets you use the PC as a TV set or PVR. They all come with included software,
which IMHO sucks, you can buy a program off the internet called DVBViewer
which is pretty good for 15 euros. Note that you will need around a 2.6 gHz
(or the equivilant multi core) PC to properly decode and record 720P or better
video.

You just need to be careful that the device you are buying supports the
compression standard used for the video, besides the transmission standard.
Israel's service is very new, so they decided to use H.264 video encoding
and AAC (aka MP4a) audio encoding. Not all of the boxes on the market could
decode them nor some of the programs for the USB sticks.

Geoff.

--
Geoffrey S. Mendelson N3OWJ/4X1GM
Those who cannot remember the past are condemned to misquote it.

 

[Dave Plowman (News)]

In article <slrniij9su.1og.gsm@cable.mendelson.com>,
Geoffrey S. Mendelson <gsm@mendelson.com> wrote:

That's why I said that the OP must of either spent the last 30 years
under a rock or in the US. In the US no one cared, everything was NTSC
or converted to it for sale, while elsewhere in the world, everyone was
trying to get multisystem TV sets and VCRs.

Why would the rest of the world want multi-standard TVs? You might if you
lived within reception distance of another country with a language you
understood well and it used a different system - but how often does this
happen?

In the UK, PAL VHS would playback NTSC tapes on a PAL TV for many a year.
Bit of a cludge, but it worked well enough for the poor quality of VHS.

--
*Why are they called apartments, when they're all stuck together? *

Dave Plowman dave@davenoise.co.uk London SW
To e-mail, change noise into sound.

 

[David]

"William Sommerwerck" wrote in message
news:igc6v0$308$1@news.eternal-september.org...

A DC synchronization aka "sync" pluse was included to
keep everything together so if signal got scrambled, the TV
would bring it back together quickly.

Actually, the sync pulses keep the horizontal and vertical
scanning in the
receiver at the same frequency and phase as the transmitted
signal.

Those rates were chosen because the studio lights were arc
lights and flashed on and off at the power line rate, so the TV
cameras had to be syncronized to them or you would get moving
black stripes across the screen.

This might have been a consideration, but the principal concern
was "hum
bars" in the receiver. Modern power supplies are sufficiently
well-filtered
that this isn't a concern.

The RCA system for compatible color TV (compatible with black
and white), used 1/4 of the color information based on the fact
that your eye only sees about that much.

Actually, it's more like 1/3.

The color information was encoded on a phase modulated 3.57MHz
subcarrier, which at the time was beyond the picture
information, but
still within the transmitted signal.

Actually, it was within the picture (luminance) information. NTSC
has always
had a potential video bandwidth of 4.2 MHz.

The original RCA system, alternated the phase of the carrier
every line,
so that it would fix itself if there was a transmssion or
syncrhonization
problem. To save money, the National Television Standards
Commitee
(NTSC) which chose the standard, dropped the alternating phase.

Actually, it was dropped because it didn't seem possible at the
time to
design a reasonably priced receiver that would take full
advantage of this
feature (in particular, the elimnation of the Hue control). Also,
the US
distribution system didn't have problems with non-linear phase,
so PAL had
little practical advantage.

Also, the original proposal used red and blue color-difference
signals,
rather than the more-efficient I and Q. The original NTSC
proposal was
virtually identical to PAL. (If you don't believe this, I have a
copy of
"Electronics" magazine that confirms it.)

The French used a different color encoding system called SECAM,
which was also based on the RCA system (1/4 color, 4.43mHz
color
carrier) but designed to be totally incompatible so that you
could not
watch French TV in England and vice versa.

SECAM stands for "sequential avec memoire".

SECAM was actually adopted because the French were idiots. They
wanted a
system that was relatively easy to record on videotape.
Unfortunately, it
made the receiver more-complex and expensive. A classic example
of lousy
engineering.

Actually there are more differences between PAL and NTSC color
encoding than the alternation of the phase:

1) NTSC I and Q color difference, PAL R-Y, B-Y
2) Different primaries, especially green. PAL had a smaller color
gamut.
3) Different color bandwidth for different colors. NTSC had 1.3
MHz for I and 0.5 MHz for Q. PAL was equal for R-Y and B-Y.
4) Excellent interleaving of chroma-luminance frequency
components which was largely destroyed by the phase alteration.

As a note, much of the advantage of points 2), 3) and 4) was lost
on early sets which just used 0.5 MHz bandwidth for decoding both
chroma components and bandwidth limiting the luminance signal to
minimize chroma-luma crosstalk. Also most sets did not use the
NTSC primary phosphors so a lot of the advantages of NTSC were
lost for a few decades. When integrated circuits became
available, dual bandwidth chroma decoders started appearing as
well as comb filters to separate the luminance and chroma
signals. More accurate phosphors were also gradually used in
sets. The result was a major improvement in picture quality with
the original 1953 broadcast standards. No such receiver
improvement was possible with the PAL system. Regarding VITS,
that was introduced, but very few sets used it.

David

 

[Geoffrey S. Mendelson]

mm wrote:

But thoss were in the analog signals. When they went to digital, why
didn't they stop using PAL or stop using NTSC? That is my point.

Because they could.

Seriuosly the digital standards were developed with keeping the old systems
in play, even if they were no longer needed.

What tied them to both PAL and ntsc at the same time?

Regional pride?

Or was it because they wanted current analog tvs to be able to receive
digital signals that went through a set-top digital to analog
converter, and some tvs wanted 50 cycle and others 60 cycle, so if the
air-borne signal was the same, it couldnt' be converted to one of 50
or 60?

It really did not matter. Maybe in 1983 when digtially encrypted HBO satellite
receviers were designed, but in 2005 when the US conversion started, it was
simple enough to use anything they wanted and produce NTSC or PAL or computer
RGB output or all three on a set top box.

The actual encoding is not PAL or NTSC anyway. H.264 which is the current
standard for high end compression does not have a fixed frame rate. I mentioned
that in a previous posting.

With a fast enough decoder chip you can take any resoltuion and frame rate
and put out anything else. My Western Digitial TV Live unit will take
almost any compressed video file up to 1080P60 (1080x720 60 frames a second)
and put it out on the fly, with audio in sync from 480i60 (standard NTSC),
or 560i50 (standard PAL), in composite, 480P60 or 560P60 in component,
or digital in HDMI with several choices in between.

Why you could not slap an ATSC or DVB-T or the Japanese standard tuner
chip (or all three) on it instead of a USB port or ethernet is more of a
matter of product placement than anything else.

Geoff.
--
Geoffrey S. Mendelson N3OWJ/4X1GM
Those who cannot remember the past are condemned to misquote it.

 

[Geoffrey S. Mendelson]

Dave Plowman (News) wrote:

Think you're well into hindsight. When the UK PAL system was finalised
(1960?), computers were some esoteric device in a lab. But in any case a
major priority of any colour TV system then was that it can be easily
receivable on a monochrome only set - and not make that set more expensive
to produce.

That's almost irrelevant. When the UK went to digital TV broadcasts (was
that around 2000 with Sky's digital terrestrial service?) there was no
no need to continue to support PAL. After all much of their material
was NTSC anyway. They were encoding the signals in one place, so there was
no restriction on what equipment was used except cost, and on the set end
they could of used anything they wanted.

I expect they chose PAL because it was the existing standard, and they could
buy subassemblies cheaply.

However ATSC was compeltely different. It was supposed to be a new standard,
not a re-hashing of an old one. There was no need to keep NTSC compability
as long as it could be created in set top boxes.

Note that there were and still are two other incompatble digital TV standards
in use in the US. The cable companies use one of their own, and the DBS
companies use a different one. Since there are two competing DBS companies,
each using their own incompatible encryption, you could say there are four
incompatible ones.

They all use some sort of MPEG TS transmission, but the streams can not
be read with the other company's devices.

Geoff.



--
Geoffrey S. Mendelson N3OWJ/4X1GM
Those who cannot remember the past are condemned to misquote it.