Your thoughts about PAL vs NTSC

[Hewitson]

Impressive? Have you ever watched an NTSC broadcast? The PAL system might not have been perfect, but it was a HUGE improvement.

Americans who came to a PAL country must have been devastated when they had to go home and watch that shit again.

[Zippy Zapp]

@Hewitson. It's not that bad. Never had a problem with any of my NTSC Commodore's and proper monitors. Sometimes TVs showed interference through the RF modulator but it wasn't so bad that it took away from the enjoyment of using the Vic or 64... Its all what you are used to and what you grew up with. If you had grown up knowing only NTSC you wouldn't give a hoot about the problems. And you might have even slammed PAL for being slower or flickering...

[mc6809e]

PAL flicker is miserable. I don't know how anyone can stand it.

[Mrs Beanbag]

NTSC televisions used to have a hue control like ours had brightness and contrast, right? i gathered the composite signal was a different format that encoded the colour differently.

[Jope]

Sure, NTSC compsosite has NTSC colour encoding, just like PAL composite has PAL colours.

If you want to read more about the tint/hue adjustment: http://en.wikipedia.org/wiki/Tint_control

Re: PAL flicker, it wasn't that much of a problem with our TV sets, they had slow phosphors. 50Hz on a VGA screen, though.. Shudder.

[amadama]

You guys in Europe were very fortunate to have televisions with SCART connections. I'd love to have those available easily to me in the USA. Connecting an RGB source like a vintage computer or an arcade game board would be so much nicer.
I also liked the extra scanlines in PAL vs NTSC and never noticed any flickering differences but did notice a more detailed picture in PAL.

[mc6809e]

Originally Posted by Mrs Beanbag

NTSC televisions used to have a hue control like ours had brightness and contrast, right? i gathered the composite signal was a different format that encoded the colour differently.

Nearly the same signal.

The only thing PAL did was invert the chroma phase of every other line so that any shift in one line could be compensated for by the next line.

It did result in reducing vertical color resolution by half, though the eye being less sensitive to color, it wasn't much noticed.

PAL's big advantage over NTSC was the choice to use 8 MHz channels instead of 6 MHz channels which allowed for noticeably higher horizontal resolution.

[pandy71]

Originally Posted by Hewitson

Impressive? Have you ever watched an NTSC broadcast? The PAL system might not have been perfect, but it was a HUGE improvement.

Americans who came to a PAL country must have been devastated when they had to go home and watch that shit again.

Same apply to old TV for example SECAM reception - example Russian Рубин-714/Д - 3 potentiometers dedicated to color purity!

NTSC evolved in time and with technology progress, lot of things was done to improve NTSC - with digital technology finally NTSC showed that it works sufficiently good - i always remember what kind of technology was used then and now - modern portable headphone amplifier IC has more active components on silicone die than previously TV vacum tubes...

[Zerotech]

It seems the old argument with PAL vs NTSC Continues on except with different names, the argument continues well into the 21st century.

Advanced Television Systems Committee (ATSC)
http://en.wikipedia.org/wiki/Advance...ttee_standards

DVB-T "Digital Video Broadcasting — Terrestrial"
http://en.wikipedia.org/wiki/DVB-T

If we were to adopt one television standard it will benefit us all in the world. Could business competition and security be the reason behind those different standards? I mean after the 9/11 attacks in the US they have taken security to a whole new level so they adopted ATSC for their own security and noone else but the US are allowed to watch their own broadcast.

While the rest of the world we use now DVB-T and America uses ATSC. What could be next?

[Michael Sykes]

I just want to mention here, that in France and some countries in eastern europe, they also used a system called SECAM.

[pandy71]

Originally Posted by Zerotech

If we were to adopt one television standard it will benefit us all in the world. Could business competition and security be the reason behind those different standards? I mean after the 9/11 attacks in the US they have taken security to a whole new level so they adopted ATSC for their own security and noone else but the US are allowed to watch their own broadcast.

While the rest of the world we use now DVB-T and America uses ATSC. What could be next?

There is few things,

First ATSC usually means something else than DVB-T (ATSC is PSI/SI standard in US where in Europe we use DVB PSI/SI), radio frequency modulation in US is 8-VSB where in Europe it is DVB-T (and after 9/11, US in NYC allowed conditionally to use DVB-T - it was more robust - multipath immune) - 8VSB was selected as being simpler to implement and slightly better efficiency (longer range with same power in transmitter) however 8-VSB have lower bitrate capacity and as such less data can be transmitted over 6MHz channel.
Japan also use own standard (AFAIR ISDB) so US is nothing exceptional.

Security is something else and probably you referring to so called M-Card (CableCard) which use strong cryptology and as such export US regulations apply to it. AFAIR 8VSB aerial broadcast is not encrypted.

Originally Posted by Michael Sykes

I just want to mention here, that in France and some countries in eastern europe, they also used a system called SECAM.

This was my point - SECAM should be free from many problems known on PAL/NTSC and still required on ancient times 3 knobs to adjust colours - nowadays with accuracy of digital processing there is no significant advantage of PAL or SECAM over NTSC.

[Michael]

Video recorders had MeSecam and a few variations of NTSC too.
Apparently VHS recordings in NTSC looked better at times then PAL. Fewer lines to record, and VHS was somewhat limited in that and matches NTSC better?.

RoboCod on Amiga had a nice touch, you could change PAL/NTSC mode by pressing one key on the fly during game play. If the TV was good you got full screen and no black empty space at the bottom (something many games had) the more clever ones centred the screen if they did not do full PAL screen.

[Michael Sykes]

Originally Posted by pandy71

This was my point - SECAM should be free from many problems known on PAL/NTSC and ...

Damm it. Above the huge picture. Didn't read it carefully enough, maybe beacause of the picture. An attachment of half the size would have done the job as well.

[alenppc]

Originally Posted by pandy71

8VSB was selected as being simpler to implement and slightly better efficiency (longer range with same power in transmitter)

And therein lies the most important factor - distance. In North America there are vast sparsely populated areas that need to be reached with least expense. It's quite different in Europe where population density is much greater.

I watch ATSC TV every day and it works exceedingly well. I am grateful I am able to receive all the US stations from across the border in Canada - except for the few unfortunate ones that chose to transmit on VHF.

Sadly the governments are trying to push over the air TV off the air by relegating the stations back to a tiny chunk of VHF spectrum so they can sell the UHF spectrum for mobile licenses.

[pandy71]

Originally Posted by Michael Sykes

Damm it. Above the huge picture. Didn't read it carefully enough, maybe beacause of the picture. An attachment of half the size would have done the job as well.

I use normal way provided by forum engine to upload picture (url) - have no control over size - as you see this is direct link to Russian page dedicated to TV's

Originally Posted by alenppc

And therein lies the most important factor - distance. In North America there are vast sparsely populated areas that need to be reached with least expense. It's quite different in Europe where population density is much greater.

Europe is very different - small countries like Netherlands or Belgium - yes, population is very dense, countries like Sweden, Norway, Italy, Spain etc are not so densely populated, sometimes difficult as mountains are present...
For me biggest limitation for 8VSB is low capacity - nett 19.3904Mbps - imagine MPEG-2 HD squeezed to 18.5Mbps... for H.264 is easier but not sure if aerial broadcast in US use H.264 (cable for sure).

Originally Posted by alenppc

I watch ATSC TV every day and it works exceedingly well. I am grateful I am able to receive all the US stations from across the border in Canada - except for the few unfortunate ones that chose to transmit on VHF.

DVB-T has few advantages over 8VSB - you have ability to select better modulation parameters (range can be increased at a cost of bitrate), Single Frequency Network, better multipath, very useful hierarchical modulation (at the same time two different modulation settings - one high and one low bitrate but low bitrate is OK for emergency broadcast/services - similar approach as EAS but not limited to metadata - approx 3Mbps bitrate is sufficient for video/audio service with extremely high range) - imagine SVC coding - where basic SD can be always received (even difficult reception, even when traveling with high speed - car/train).
But 8VSB was easy (cheap) to implement (no FFT 2048/8192 processor required).

Originally Posted by alenppc

Sadly the governments are trying to push over the air TV off the air by relegating the stations back to a tiny chunk of VHF spectrum so they can sell the UHF spectrum for mobile licenses.

Same in Europe - dying economy, permanent public debt - they named this "digital dividend" but... last time government "allowed" to use non occupied spectrum in UHF range (so called 'white spaces').

[mc6809e]

The idea that the OFDM of DVB-T is multipath resistant is mostly a myth.

It should be obvious that mixing the OFDM signal with a carrier re-narrows the signal and the multipath advantage almost completely disappears. If the carrier is at frequency fc, and fc is very large compared to the bandwidth of the signal, then any phase shift combined with the original signal looks like simple amplitude modulation. All the small additions to fc due to mixing still create frequencies that are very close together.

The big, huge, enormous advantage of any OFDM signal, which is almost always ignored for some reason, is that individual bits are spread in time to the greatest extent possible, making the bitstream much more resistant to impulse noise which is the bane of any system. Schemes that look great when modeled using Gaussian noise fall flat on their faces when having to deal with real world noise from motors, lightning, and relays.

8VSB is terrible at handling impulse noise. A simple flip of a light switch is enough to interrupt the stream and allow audio to drop out.

In the case of 8VSB, the bit spreading is accomplished digitally and combined with error correction. It still stinks compared to OFDM, though it could have been better.

Multipath for 8VSB is handled easily using a comb filter because each bit looks like an impulse that went through a sinc filter.

[r.cade]

It was my understanding (from one class in broadcast engineering from Georgia Tech) that you could actually create a PAL color decoder from two NTSC decoders. Each decoder handles every other line, and then the outputs are connected together (summed) to "average" them.

The way PAL fixed the possible phase (hue) errors of NTSC was to send the inverted vs non-inverted color information on every other line. I think because of this, the color information is averaged over two lines, which makes it possible for more muted colors. Possibly less "saturation" as we call it.

It must have been a big problem for broadcast TV in the 1950's for them to go through all the trouble to make a new standard.

Now, this is back in the broadcast days. I believe that the phase errors never really occurred in Cable TV, and definitely not Satellite transmissions, which are only converted to NTSC for the last 6' of cable.

I was born in the 1970's - we had Cable TV by then.

[pandy71]

Originally Posted by mc6809e

The idea that the OFDM of DVB-T is multipath resistant is mostly a myth.

It should be obvious that mixing the OFDM signal with a carrier re-narrows the signal and the multipath advantage almost completely disappears. If the carrier is at frequency fc, and fc is very large compared to the bandwidth of the signal, then any phase shift combined with the original signal looks like simple amplitude modulation. All the small additions to fc due to mixing still create frequencies that are very close together.

The big, huge, enormous advantage of any OFDM signal, which is almost always ignored for some reason, is that individual bits are spread in time to the greatest extent possible, making the bitstream much more resistant to impulse noise which is the bane of any system. Schemes that look great when modeled using Gaussian noise fall flat on their faces when having to deal with real world noise from motors, lightning, and relays.

8VSB is terrible at handling impulse noise. A simple flip of a light switch is enough to interrupt the stream and allow audio to drop out.

In the case of 8VSB, the bit spreading is accomplished digitally and combined with error correction. It still stinks compared to OFDM, though it could have been better.

Multipath for 8VSB is handled easily using a comb filter because each bit looks like an impulse that went through a sinc filter.

COFDM so not plain OFDM, second - OFDM have better performance (for sure when dynamic multipath is present then 8VSB is outperformed) but for sure is not totally immune to multipath problems.

http://eshare.stust.edu.tw/EshareFil...5_777417f9.pdf
http://www.ofcom.org.uk/static/archi...project508.pdf
http://www.ehu.eus/tsr_radio/images/...EIZM-11-01.pdf
http://www.itu.int/ITU-D/pdf/3888-06-en.pdf

[mc6809e]

The first is just a student's report drawn from other sources. Nothing there really.

The second is a test of multipath, but at the smallest tested interval of 2 microseconds, the interfering path is still about 600 meters longer than the direct path! That's a bit large to test the theory behind the multipath resistance of OFDM (okay COFDM if you prefer) which is that the spacing of subcarriers allows for constructive and destructive interference, one compensating for each other.

To test that theory of the system, the path delays would have to be on the order of 1/818MHz which corresponds to 1.22ns. As a result of the long delays used in the test, what's being tested is not so much the multi-carrier aspect of the system, but the strength of the forward error correction. But it should be obvious what will happen for delays of 0.61ns+N*1.22ns -- destructive interference.

The third paper suffers from similar problems.

The fourth paper is worth looking at since it's a real world experiment.

In that paper 8VSB falls below DVB-T (8k) for impulse noise > 200 microseconds.

And for multipath the paper admits that the performance of DVB depends not on the multicarrier aspect of the system but on the forward error correction (and interestingly enough, 8VSB actually performs better in noisier environments than all other systems when the C/E is greater than 5 dB).

[commodorejohn]

Originally Posted by Hewitson

It has always amazed me that the USA did not design their TV system to be compatible with the system that was being used for movies.

The really funny part is that the powers that be went and created a new TV standard from scratch, and they still made it incompatible with the system used for movies...ai yi yi.

Also, the US and Japan aren't the only countries to use NTSC. Canada and much of Central and South America do as well.

And yes, NTSC's color stability sucks, but I'd still take 60fps any day.