Talk:Broadcast television systems

Some thoughts for future research
Some thoughts for future research:
 * There should be a history section describing how the formats evolved and when various systems were phased out in the countries that used them.
 * Whatever happened to system C? I know I've seen a version of this table with the parameters, but I can't find it any more.
 * Why did the French go with 819 lines? Why did the French stick with AM audio and positive video modulation (thereby unnecessarily bringing system L into existence) when nobody else did (including their SECAM allies in the OIRT, and even their own overseas departments, which implemented system K instead)?
 * Because they were French :P Seriously, it was just the way that television in France was developed. Remember that at the time, television was a competitive project, and each country was trying to develop the system, perhaps in the hope that their system would gain acceptance, and could be exported, along with patent rights, etc. In England, we arrived at 405-lines, because that was considered to be a 'broadband' signal at the time. Plus it was a case of being able to physically transmit a picture on the available wavebands, thus the picture-standard had to be developed to be compatible with that. (RM21 00:39, 26 June 2006 (UTC))
 * Should there be a section on bandplans? They seem to be few in number, and they certainly had an influence on the technical parameters of the systems (particularly on VHF, as witness system B's 7-MHz channels, and system L's -6.5 MHz audio offset).


 * What's up with Brazil?
 * Brazil uses PAL-M, which has its own wikipedia article, no need to cover it here too. This article links PAL-M already. Jaho (talk) 11:17, 6 December 2007 (UTC)


 * Can the layout of the big table of systems be improved any?


 * Just added a section on the French 819 line standards. Why they opted for variations in their 625 line standard is not quite clear, maybe they just wanted to be different. Just like the UK :). Anorak2
 * Hey, the UK only went for System I because we (Ireland) were using it - couldn't deny those Welsh people their RTE One :p Seriously, System I was used in Ireland first by around two years but I'd assume the BBC had a huge part in developing it. --Kiand 14:41, 11 March 2006 (UTC)
 * Yes, but in Ireland, the difference was the previous systems were upgraded from 405 to 625-lines, on vhf. In the UK, vhf channels were seen as troublesome [because of problems with temperature inversions and long-distance reception], and old-fashioned, so they were closed. The UK could have as easily opted for the B/G system, which would have had the advantage of being compatible with Europe; this would almost certainly have been chosen today. (RM21 00:39, 26 June 2006 (UTC))
 * System I was developed in part because it was felt (rightly or wrongly) that the 5.5 MHz video/sound seperation in System B/G constrained the video bandwidth too much and gave rise to inadequete sound/video seperation. (On the other hand it is more bandwidth efficent -at least on VHF) But why on earth didnt they (along with the French) opt for the existing (and Superior) System D/K (wider video bandwidth and greater sound/video seperation than either systems I or B and overall channel bandwidth identical to System I) ? Could they really not stomach using a Soviet developed system ? And incidently did the BBC really choose System I in order to remain compatible with an Irish developed system or was system I developed in the UK and RTE having prior knowledge that the Beeb planned to use it decided to adopt it as well ? Its hard to imagine the BBC going out of their way to facilitate (non UK television licence paying) Irish viewers 213.40.217.126 (talk) 21:33, 7 December 2008 (UTC)


 * Concerning Brazil: They are regular system M just like North America, but opted for PAL colour probably following an advertising campaign by Telefunken. At least that is what Walter Bruch (PAL inventor) writes in one of his essays. Is it worth mentioning in the main article? Anorak2 11:04, 1 February 2006 (UTC)
 * If that's the extent of the story it's probably not worth repeating. I still hold out hope that there is a specific government report or published history which someone can cite for an official explanation.  121a0012 05:52, 2 February 2006 (UTC)

System J
Why is there no system J?? 66.32.240.129 14:07, 6 Sep 2004 (UTC)
 * Because I and J are often confused. Anorak2 11:04, 1 February 2006 (UTC)
 * There is a system J, see the table again. System J is the Japanese system and it differs only from the American system M in the black level. System M has different blanking and black levels, on system J they're equal (see ). Systems J and M are often confused. Jaho (talk) 07:40, 6 December 2007 (UTC)

Frame rate
"(However, the choice of a 25 Hz frame rate has some unfortunate consequences for the telecasting of movies, most of which are filmed at a 24 Hz frame rate.)"

As I see it, the only unfortunate consequence for movies is that they run slightly faster and unless the soundtracks are digitally pitch-corrected they're about a semitone highter. But since the movies are screened at the same frame rate as video the motion appears perfectly smooth, as opposed to NTSC at 30 frames (OK, 29.97, whatever) where there's either motion judder or motion blurring except with modern equipment that can correct for them. Lee M 20:14, 4 Nov 2004 (UTC)


 * It should be incorrect. Most TV sets either work at 50Hz or 60Hz framerate. 24/25/29.975 refers to the frames per second (framerate), as TV broadcasts are interlaced (each redraw is done two-pass: first pass for odd lines, second redraw for even lines). RAM 02:16, 24 August 2006 (UTC)

jidder, etc.
"Ignoring color,  all  television  systems  work  in  essentially ": say if analog, non analog or both.

Also jidder: jitter.

System I
I thought System I was 29.975-30fps. Can anyone check it out? My mom's a TV technician, and she once told me that PAL-I is 60Hz, which almost certainly means ~30fps interlaced. (Local TV stations here uses PAL-B/G, and she once modified an old PAL-B/G TV set so I could use a PAL-I game console on it).RAM 02:09, 24 August 2006 (UTC)
 * There's no bloody way PAL-I works on 60hz!! ALL the countries it has been introduced [with the exception of Macau, maybe], use 230v AC supply, at 50hz. If we used a 60hz signal, it'd bust our tv's :S (158.125.9.4 01:41, 18 November 2006 (UTC))
 * PAL-I is 50 Hz interlaced (25 fps). 100% definitely. Your mom's mixing it up with PAL-M or something. The mains frequency is irrelevant. Harumphy 11:47, 18 November 2006 (UTC)
 * PAL-I has a different sound carrier, thats all. Its definately 25fps. --Kiand 08:09, 22 June 2007 (UTC)
 * Probably mom (or you) is mixing up systems I and J. System I is 25 fps; system J is the 30 fps Japanese system, which is almost equal to system M (see the table in the article). Let me guess: was it a private import Japanese game console? Jaho (talk) 07:17, 6 December 2007 (UTC)
 * You are showing your ignorance of TV systems yet again. The mains frequency is very important.  In the days of CRTs, the image was heavily distorted by stray magnetic fields from nearby motors, transformers, etc.  By chosing a field frequency the same as the mains frequency, the distortions, though present, would be stationary and relativley unnoticeable.  In most countries in the world (with the notable exception of those countries using system-M), the frame frequency is synchronised to the mains frequency. 86.182.66.217 (talk) 12:52, 21 May 2010 (UTC)

Channels
I have two questions, and they may be related....first, what does the chart mean by "b/w"...is it black and white? second, i think someone should mention the channel width for each system....

oh, and are there any multi-standard TVs that read both NTSC and PAL? (i know of SECAM/PAL TVs...)  The Legendary RaccoonFox • Talk • Stalk''' 20:35, 16 December 2006 (UTC)
 * If there are, they'd be PAL-M/N(C)/NTSC sets, surely?? NTSC is mostly only found in North and South AMerica, not in Europe, Africa, or most of Asia. If you were a tv manufacturer, you might want to consider developing a set that could be exported to Brazil/Chile/Argentina, etc. But it wouldn't be much good in Europe/Australia, etc.
 * Most PAL/SECAM sets can easily be transferred between European countries, as you'd expect. Many of those countries also use the same broadcast system (i.e. B/G), so they can watch broadcasts regardless of colour format. (RM21 06:02, 19 December 2006 (UTC))

There are multi system television sets and VCRs of almost any conceivable standards combination available. Some will only accept A/V signals, some others will also have an appropriate tuner for off-air reception. Sets with PAL-B/G and NTSC/M reception amongst others exist. Anorak2 08:37, 14 May 2007 (UTC)

Frames
This section concerns the explanation about frames. Scetpfe 16:58, 24 February 2007 (UTC)

About: "Usually it is closely related to the frequency at which the electric power grid operates, to avoid the appearance of a flicker resulting from the beat between the television screen and nearby electric lights."(end quote)

I propose that only pre-1970 sources be used for this explanation because this is the period when the field rate decisions were made world-wide, and it's also the same period where only one explanation ("Hum Bars", not the above explanation) was ever given for this choice.

The rest of my talk are thoughts on why I think the pre-1970 literature is correct, and can also serve as the skeleton of an expanded explanation if the appropriate sources are cited.

I think there is indeed a small flicker effect as mentioned in the present Wikipedia article, but I've found that in CRT-based computer monitors, a mis-match produces even less flicker. I use 72 or 75 Hz vertical refresh instead of 60 Hz because it reduces considerably the amount of flicker. That's one reason why I think the present Wikipedia explanation is not correct.

Flicker occurs from a combination of two properties, which is screen brightness and field refresh rate. Reducing one property can offset the increase in the other property. But the tradeoff is very disproportionate. Tests have shown [need to find a quote. I've read this in more than one place.] that an increase in field frequency from 50 Hz to 60 Hz requires a ten-fold reduction in pictures brightness in order to keep the same level of perceived flicker.

Yet, European TV systems use only the 50 Hz rate, causing the need to mitigate the flicker in CRT-based European TV with a combination of longer phosphor persistance, lower picture brigtness and viewer adaption over time. So why would the Europeans still use 50 Hz instead of 60 Hz in order to match the European power grid frequency of 50 Hz?

The reason is another kind of beat phenomenon even worse than the 50 Hz flicker. It's "hum bars" caused when imperfections of the TV receiver's AC to DC power conversion circuitry (power supply) leaks some of the AC into the DC (this leakage component known as power supply "ripple"). This produces the horizontal shadow-like bars, and also some geometric picture distortion near the bars. If these bars, along with the accompanying geometric picture distortion, are also allowed to move up or down, the movement calls attention to the bars, making them much more noticable.

It's too expensive to reduce the hum bars completely to zero, so an almost invisible degree of hum bar is allowed in the TV design. If the hum bar is not allowed to call attention to itself by moving, then the reciever cost can be reduced considerabley by allowing a greater intensity of hum bar before it becomes noticable.

As the electrolytic capacitors inside the TV wear out or dry up over time, the hum bar becomes more intense, and it then becomes even more important that the hum bars not be allowed to move.

And the way to stop this movement is to make the field repetition rate the same as the power grid frequency, which is the AC power going into the TV set.

After about 1985, "switch-mode" power supply design, which often completely removed hum bars, became popular, making this issue moot after 1985. But by then, the field frequencies have since long been chosen. Scetpfe 19:59, 24 February 2007 (UTC)


 * You are partially correct. It wasn't only the 'hum' from the power supply that was the problem.  The picture was also distorted by stray magnetic fields from nearby motors, transformers, etc. directly deflecting the electron beam in the CRT. 86.182.66.217 (talk) 12:56, 21 May 2010 (UTC)

Modulation
This concerns "At the time television was developed, the vestigial sideband was easier to accomplish than true single-sideband modulation; with today's technology, there is no reason for it except to be compatible with existing technology" (end quote)

Actually, in the United States, digital television also uses amplitude modulation with a vestigial sideband scheme, although it's indeed much closer to true single-sideband operation than in the analog system. It uses this not for compatabiity, but because filtering in the receiver would otherwise be prohibitively expensive. Scetpfe 20:21, 24 February 2007 (UTC)

Audio
"Most commonly, the audio and video are combined at the transmitter before being presented to the antenna, ..."

I think this is more clear: "Most commonly, the audio transmitter output is combined with the video transmitter output before being presented to the antenna, ..." Scetpfe 20:26, 24 February 2007 (UTC)

Spelling: Analogue or Analog?
Being American I've never even seen the 'gue' (or perhaps noticed it) prior to reading this article. Google hits:

Analog  80,900,000 Analogue 28,100,000

Wikipedia's own disambiguation page for Analog makes a bold assertion:

"In the U.S., the spellings analog and analogue are interchangeable for the noun (except, for example, in the literary sense above); the adjective is usually spelled analog. In the rest of the English-speaking world the spelling is usually analogue for both noun and adjective; see og/ogue. However, the spellings given above should be retained in cases where it forms part of a name or is an acronym."

I've read a good deal of American Electronics and Computer texts and never seen it... the claim that "In the U.S., the spellings analog and analogue are interchangeable for the noun..." seems generally false. If there are U.S. writers who prefer the 'gue', they must constitute a rarely visible minority.

Seems like a waste of two bytes, and a bumpy read for the majority. --AC 07:31, 22 June 2007 (UTC)
 * Wikipedia policy is generally to leave spellings as they are. If its spelt "analogue" here, it should be left as such.--Kiand 08:06, 22 June 2007 (UTC)


 * That's interesting, because I know of no other encyclopedia with such a policy. Please, do you have a Wikepedia policy link for this?  I'm curious how it works.  Maybe you'd agree a phonetic spelling like "anallohg" would be wrong, and we can consider only British versus American spelling.  If so, is the rule per article, or is it anything goes?  Do we permit alternate British & American spellings of the same term in one sentence, or paragraph, subheading, article, where's the boundary?  And who decides on the original spelling -- is it just random, based on wherever the first writer is from; a pragmatic compromise to forestall nationalistic orthographic conflict at the small cost of mild reader dizziness?


 * A 'locales' policy would be better -- say we could tag certain terms as having alternate national spellings, and as per one's browser setting, all readers would see their nationally correct spellings. --AC 09:24, 16 July 2007 (UTC)


 * The rule is per article. Please see Manual_of_Style. As this article has no particular national association, the spelling for this article should be that used by its first major contributor (18.24.0.120), who used both "analogue" and "color". That IP belongs to MIT. Therefore, and despite being British myself, I think that American spelling should be used for this article. --Harumphy 11:51, 16 July 2007 (UTC)


 * I am the original author of this article and I prefer the "ue" spelling, which is why I used it. The monolithic "American spelling" you posit is an illusion.  (That being said, there is no ownership of Wikipedia articles so I'm not about to get into an edit war over the spelling of an adjective.)  121a0012 03:41, 17 July 2007 (UTC)


 * In that case, particularly as you are the original author, I think we should keep the "ue". Harumphy 08:54, 25 July 2007 (UTC)


 * Then is the Wikipedia rule "national spellings" within articles, as picked at will by the first author regardless of merit? While 121a0012 may be sincere in his valid enough skepticism about American standards, mere sincerity shouldn't oblige us to accept any unsound conclusions.  --AC 19:53, 25 July 2007 (UTC)


 * You can see the rules for yourself - I've already cited them above. The first major contributor's choice is one of several factors that should be taken into account. Harumphy 09:39, 26 July 2007 (UTC)


 * Thanks... sorry if I hadn't made it more clear that I had indeed read those rules when you first cited 'em. Still, after a second perusal, I find no compelling reason to retain the 'ue'; to the contrary:


 * 1) Violates 'Consistency within articles'. It could be 121a0012 doubts an underlying premise of this rule, after claiming American spelling does not exist.


 * 2) Violates 'Opportunities for commonality': one of my later reactions was to wonder if 'analogue' was a related technical term of 'analog' having some minor yet significantly different shade of meaning.  (e.g. the grandfathered misspelling of 'referer' in the standard HTTP technical term "referrer".)


 * 3) Clearly an MIT or academic dialect exists where 'analogue' is accepted. It's either an American dialect spelling, (in which case standard American should trump it), or maybe a grandfathered instance of hypercorrection.  According to the Wikipedia rules you've cited, the language boundary is National varieties of English, therefore a sub-national variant spelling is not preferred.


 * In closing, an apt quote from Noah Webster:



But an attempt to fix a standard on the practice of any particular class of people is highly absurd: As a friend of mine once observed, it is like fixing a light house on a floating island. It is an attempt to fix that which is in itself variable; at least it must be variable so long as it is supposed that a local practice has no standard but a local practice; that is, no standard but itself. While this doctrine is believed, it will be impossible for a nation to follow as fast as the standard changes...

...If a standard therefore cannot be fixed on local and variable custom, on what shall it be fixed? If the most eminent speakers are not to direct our practice, where shall we look for a guide? The answer is extremely easy; the rules of the language itself, and the general practice of the nation, constitute propriety in speaking. If we examine the structure of any language, we shall find a certain principle of analogy running through the whole. We shall find in English that similar combinations of letters have usually the same pronunciation; and that words, having the same terminating syllable, generally have the accent at the same distance from that termination. These principles of analogy were not the result of design--they must have been the effect of accident, or that tendency which all men feel towards uniformity. But the principles, when established, are productive of great convenience, and become an authority superior to the arbitrary decisions of any man or class of men. There is one exception only to this remark: When a deviation from analogy has become the universal practice of a nation, it then takes place of all rules and becomes the standard of propriety. --[http://edweb.sdsu.edu/people/DKitchen/new_655/webster_language.htm An Essay on the Necessity. Advantages, and Practicality of Reforming the Mode of Spelling. 1789]
 * --AC 05:58, 27 July 2007 (UTC)


 * Thanks for the info Harumphy. The per article standard:  someone might write an article in an uncommon dialect, and argue like Philip Gove that because all dialects have standards, so all dialects are standards, therefore it's ignorant and cruel to discriminate against any.


 * With 121a0012 I agree that any one instance of spelling is minor, but would not agree that "American spelling" is an illusion, rather it's a convention -- by a similar logic any social or moral custom widely but not universally held becomes an "illusion". Consider customs as not unlike the rules of a game, and if we change the rules the result is in effect an attempt to play a different game.
 * You seem to have missed the point. "American spelling" does not exist.  There are certain tendencies that most users of American English have in common, but few people share all of them, and not even authoritative dictionaries agree over "analog" being the predominant spelling.  (I checked my paper American Heritage Dictionary, and it glosses "analog" as "Variant of analogue."  The online Merriam-Webster, by contrast, considers "analog" and "analogue" to be two separate words.)  Both dictionaries agree on "gray" over "grey", although the latter form is still more common than one might infer.  121a0012 04:17, 25 July 2007 (UTC)
 * Well, it depends how we define our terms -- clearly we're using the term "American Spelling" in two different senses.  When I say "American Spelling" I mean like 'color' (vs. the British 'colour' etc.) -- those spellings exist.  Based on what you've written, "American Spelling"(121a0012 usage) could only exist with the aid of an American version of the Académie française... before proceeding it might help if you could be more specific as to what you what attributes you consider "American Spelling"(121a0012 usage) must possess in order to "exist".


 * Probably most American scholars who've given the matter any thought are comfortable with variant spellings of any given term, but we don't believe every variant has equal weight or merit, and we proceed happily with somewhat informal and occasionally arbitrary conventions and standards.


 * Nothing against American Heritage Dictionary, but at present it's an ambitious 2nd tier dictionary -- the current two most comprehensive (one hesitates to apply the word "authoritative" to a dictionary outside of France) English dictionaries are the OED and Webster's Unabridged. Between their hardcovers for analog/ue usages, you'll find nothing much, probably the matter never came up before.  There's some etymology, beginning with the Greek ανά + λόγοs, the obscure 'analogon' in 1810, 'analogue' imported from France 1834, 'analog' sometime later, but their etymology and usages seem to be dated hand-me-downs from prior editors.


 * It seems at present the big dictionaries can't answer the question of whether there is any American standard spelling, and indeed probably their neglect of this term is an indirect cause of our present woes. What to do?  Do what dictionary makers do:  observe and collect usages, rank them by some method, frequency, authorial influence or excellence; I'm confident from my computer readings what the answer is.  (e.g. try Googling for 'analog' and respectively authorities like 'Donald Knuth', 'Dennis Ritchie', 'Bill Gates', 'Linus Torvalds', etc.) --AC 19:53, 25 July 2007 (UTC)


 * I'd still vote to drop the 'ue', but first would like to ask anyone if there are obvious or compelling reasons to prefer the 'ue' for general or technical usage. Perhaps the question should be whether it's possible for there to be a compelling reason in a question of this type.  --AC 07:39, 24 July 2007 (UTC)


 * I think this discussion has gone on for long enough now, so I've created a 'vote' section below so that we can move to a decision. Harumphy 09:10, 27 July 2007 (UTC)


 * Hmm, "long enough" seems uncharitable, the underlying issue is what's interesting, if only to me based on the replies so far. Regarding voting, I'll try it, but doubt if orthography benefits -- would Noah Webster's reforms survived a vote in his day?  Probably the majority that's used to 'analog' isn't going to find the topic exciting -- it's merely there, it's not a lively issue, so a well-meaning minority could prevail.  Whereas if we stick to arguing from merits and defects, we all may learn things and there's an interesting dialog left over for posterity.  --AC 19:13, 1 August 2007 (UTC)

Spelling: Analogue or Analog: vote
Please keep discussion in other section: this is for voting only.


 * Analogue. Harumphy 09:10, 27 July 2007 (UTC)
 * Analog. AC 18:54, 1 August 2007 (UTC)
 * Analogue. Jaho (talk) 22:27, 4 December 2007 (UTC)
 * Analog. VMS Mosaic (talk) 19:44, 19 January 2008 (UTC)
 * Analogue.Machete97 (talk) 19:22, 22 May 2008 (UTC)
 * Who put this goo in my analog? DMahalko (talk) 08:50, 13 August 2008 (UTC) (Advocate for separate en-us and en-uk versions of wikipaedia.)

Map of BTS's
anyone want to include this image ? http://en.wikipedia.org/wiki/Image:PAL-NTSC-SECAM.svg —Preceding unsigned comment added by Machete97 (talk • contribs) 19:19, 22 May 2008 (UTC)

Broadcast Engineering and Technology Taskforce
Persons interested in this article's content may also be interested in joining the discussions at the new Broadcast Engineering and Technology Taskforce of WikiProject Television. --tonsofpcs (Talk) 03:40, 19 July 2008 (UTC)

Two systems in TV transmitters
One addition to the following statement:

Most commonly, the audio and video are combined at the transmitter before being presented to the antenna, but in some cases separate aural and visual antennas can be used.

Well, separate antennas method must be a very old system. Being a man of profession, I have never seen such a system. In all modern analog transmitters video and audio are combined within the transmitter. But there are two methods of combining : Split sound refers to transmitters where the visual and aural RF are combined just before the antenna, intercarrier system refers to transmitters where they are combined in low power (ie which are usually called exciter) stages even before frequency conversion. Nedim Ardoğa (talk) 06:13, 13 October 2009 (UTC)


 * Speaking for Europe, the picture and sound are broadcast on separate transmitters. For the UK 625 line system, the sound carrier frequency is 6MHz higher than the vision frequency.  For pretty well the rest of Europe, the sound is 5.5MHz higher.  The 2 signals beat in the receiver to produce a sound signal that is the difference between the carriers known as the 'intercarrier frequency' which is extracted from the (picture) intermediate frequency amplifiers. 86.166.66.41 (talk) 18:15, 6 February 2011 (UTC)

At the receiving end British sets tended to work a different way between the 405- and 625-line systems. The norm in 405 sets was to filter the I.F. after down-conversion and feed it through separate vision and sound I.F. amplifiers to separate detectors. For 625, with its FM sound system, the intercarrier method was normally employed, passing the whole bandwidth through a single I.F. strip to the demodulator and then picking off the frequency-modulated sound with a 6Mhz trap. 31.185.193.87 (talk) 16:26, 23 November 2013 (UTC)

ATSC/A53 vs. ANSI/SCTE 07
The article incorrectly states that U.S. digital cable television transmission standards are part of the ATSC's body of work. Specifically, that article implies that the U.S. digital cable transmission standard is the same as the ATSC A/53 standard for digital terrestrial television in which the modulation technique has been modified from 8 VSB to QAM. In fact, U.S. digital cable television transmissions are described by ANSI/SCTE 07 which is published by the Society of Cable Television Engineers. While ANSI/SCTE 07 and ATSC/A53 share many similarities, they differ by more than just the modulation technique. To my knowledge, neither standard even references the other one. A proposal was put forth by the ATSC to use a modified version of A/53 with 16 VSB as the modulation method, but was rejected long ago by the cable television industry. —Preceding unsigned comment added by 24.124.54.158 (talk) 02:37, 22 May 2011 (UTC)

Requested move

 * The following discussion is an archived discussion of the proposal. Please do not modify it. Subsequent comments should be made in a new section on the talk page. No further edits should be made to this section. 

No consensus to move. Vegaswikian (talk) 20:07, 13 December 2011 (UTC)

Broadcast television systems → Broadcast television system – Use the singular form? Lmatt (talk) 18:05, 6 December 2011 (UTC)
 * Oppose, this article talks about many different systems. --Wtshymanski (talk) 18:36, 6 December 2011 (UTC)
 * The above discussion is preserved as an archive of the proposal. Please do not modify it. Subsequent comments should be made in a new section on this talk page. No further edits should be made to this section.

Table of systems
The table of systems is now much too wide, and uses long-obsolete units of measurement to boot. 121a0012 (talk) 02:52, 7 December 2011 (UTC)
 * The original units were supported by the reference I added, but since c/s = Hz I have changed the units to be more modern. Lmatt (talk) 04:20, 9 December 2011 (UTC)

Netherlands
Did the Netherlands ever use the 819 line system ? Bar some early experiments with 567 lines they always used System B surely ? variants of the 819 line system were used in the French speaking part of Belgium. 90.213.194.155 (talk) 13:19, 27 October 2015 (UTC)

Terrible move
"Colour broadcast of television systems" ? I thought this was the English Wikipedia. Could someone explain to me why this was thought a better title than "Broadcast television systems", which was less ambiguous and more in keeping with usual English syntax and the way this is discussed in grown-up publications. --Wtshymanski (talk) 21:13, 29 September 2016 (UTC)

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Aspect ratio
Could someone please add the aspect ratios to the big table? Thanks. &#x27A7; datumizer   &#9742;  19:11, 24 June 2020 (UTC)

UHF system D in Mainland China
Is Mainland China is using system D on UHF like Australia or system K conjunction with system D? HarmonZach (talk) 12:43, 5 July 2023 (UTC)