Talk:NTSC

message: I asked User:Blaxthos if the article still warranted the cleanup tag and the response was  Thanks for the note. While the article has improved considerably in scope, I still think there are some problems with the article structure and tone. There's a lot of very technical information that should probably be confined to the Technical Details section, and a good portion of the article uses informal voice ("This is done by...", "You could think of it as...", etc.) The content on the whole is really good, it just needs some formalization.  --Wtshymanski (talk) 14:32, 26 January 2009 (UTC)
thread_title: Cleanup tag

message: There is an article, Television that has almost the same information.  Why this duplication of effort? --Ohgddfp (talk) 23:28, 18 March 2009 (UTC)
replies: text: Because it doesn't have almost the same information? --Wtshymanski (talk) 02:41, 19 March 2009 (UTC)

text: NTSC was the name for the group doing the original US standard, but is mostly known for the US originated color standard around 1954.  Parts specifically related to that color TV standard should go here, and there should also be PAL and SECAM articles for those color TV standards.  The television article should have the basics for color TV, leaving the fine details to the specific articles. Gah4 (talk) 16:01, 12 May 2017 (UTC)
thread_title:  NTSC / Television - Duplicate Effort 

message: [NOTE: I use brackets for comments in order to differentiate those comments from suggested material.]
[NOTE: My wording is not so good, and so I can use help at some point to make it much better.]
Video
: [Use a common dictionary definition here]   (See Video Signal)
Video Signal
: A closed-circuit signal, which is a signal that is either inside a cable or inside an instrument such a TV transmiiter or TV receiver, that carries a single channel of changing graphical information such as a motion picture or radar image.  This information is used ultimately for reconstructing the motion picture or changing graphic onto a viewing screen.  The video signal supplies the information only in real time, as needed to update the viewing screen.
:For motion picture television-like applcations, the moving picture is comprised of a series of still pictures (video frames) displayed one after the other in rapid succession at the rate of approximately 10 to 100 frames per second, giving the illusion of motion in the same manner as with motion picture film.  The information of a given still picture (video frame) is delivered by the video signal only a short time before the viewing screen device uses that information to reconstruct that given still picture.  This just-in-time frame-by-frame delivery of the information is called streaming.  For analog broadcast TV, the delivery of a given frame is millesconds before it's displayed.  For digital signals that are using digital image compression, pieces of a frame may be conveyed at slighty different times, requiring reassembly at the receiving end.  This causes as much as approximately half second delay between the time all the pieces of a particular frame are sent, and the time it is displayed onto the viewing screen.  This dealy in processing of the digital video information sometimes causes lip-sync problems.  The frame rate for broadcast analog low-power TV in the United States is approximately 30 frames per second, while the frame rate for digital broadcast TV varies from about 23.97 frames per second to 60 frames per second.
Video Frame
:A video frame is a still picture that is one of a continuous series of still pictures displayed in rapid succession to give the illlusion of motion.  The information of a given still picture is ultimately used for reconstructing that picture onto a viewing screen.
:Since a 2-dimensional still picture is really only variations of light over a flat surface, the picture can be electronically captured by a lens focusing an image onto the flat surface of an electronic image sensor that is covered with a sufficient number of light detectors (pixels) that together record the variations of light over that surface.  The more light detectors there are, the closer the detectors are to each other, and the closer that neigboring light values can be located near each other while differences in their light values are still able to be resolved.  This in turn allows the capture of details that are more finely (highly) defined.  A video frame in a high definition (high resolution) system requires at least 1024 columns and 768 rows of pixels.
:Monochrome (Black and White) Systems
:Each light detector, called a picture element (pixel), converts the amount of light falling on it into a quantity of electricity.  In this way, the information carried by the electrical quantity associated with a given pixel is the quantity of light falling onto that pixel.
:A viewing screen consisting of many rows and columns of light sources, such as light bulbs or light emitting diodes, can reconstruct the image by connecting the individually amplified electical values of each sensor pixel to the correspondingly located display pixel.  The brightness of the display pixel is detemined by the quantity of electricity applied to that pixel, which in turn was determined by the amount of light falling onto the correspondingly located image sensor pixel.  So the variations of light are reproduced pixel by pixel over the entire surface.
:The amplified electrical value of each pixel may be made available by switching the values onto a single wire, one pixel at a time.  Alternately, the pixel values may be digitized and written to memory for later read out into a digital to analog converter, the output of which is also the amplified electrical value of each pixel.  The reconstruction onto a viewing screen can be much more econmically carried out by transferring the amplified electrical value of each individual sensor pixel one at a time over a single wire that is connected to the display.  In the display, each electrical quantity is electronically switched to the associated display pixel. Generally, the sensor pixel values are transferred row by row starting with the top row, and within each row, column by column.  So the pixel values are read from locations in time order are like reading words on a page, left to right, starting at the top.  For 1024 x 768 digital television, more than 700 thousand pixel values must be transferred for each video frame.  With 60 video frames per second, that equates to more than 47 million light values tranferred each second for a black and white television program.
--Ohgddfp (talk) 16:14, 19 March 2009 (UTC)
thread_title:  Knowledge Tree in the style of an Index 

message: About "Color information was added to the black-and-white image by adding a color subcarrier of 4.5 × 455/572 MHz (approximately 3.58 MHz) to the video signal." --Ohgddfp (talk) 15:04, 21 March 2009 (UTC)
replies: text: Well, the wording is confusing.  I would say something like this (with even better wording than mine) --Ohgddfp (talk) 15:04, 21 March 2009 (UTC)
replies: text: "Color information was added to the black-and-white image by modulating a 3.58 MHz color subcarrier with color-difference (colorizing) information, and then adding the result to the black and white video signal to produce a composite video signal. --Ohgddfp (talk) 15:04, 21 March 2009 (UTC)

text: I'm talking here about the portion from the above that says, "... later defined as RS-170a ...".  RS-170a is a proposed standard that was never officially adopted by any of the private standards bodies.  The timing portion of this standard did however become industry practice never-the-less. --Ohgddfp (talk) 14:39, 25 March 2009 (UTC)

text: But some other parts of RS-170a may be contrary to federal regulations.  I haven't seen the entire standard, but I will be getting it though library loans to see its general coverage. --Ohgddfp (talk) 14:39, 25 March 2009 (UTC)

text: So I would just take out the "(later defined as RS-170a)". In its place I would get a definitive reference for broadcast grade picture monitors, broadcast grade studio camera manufactures or broadcast grade telecine film chains that sell to the TV networks that one or more of the specs, either by conforming entirely to SMPTE-170M or entirely to RS-170A, or some other spec that is contrary to federal regulations (FCC rules).  Broadcast grade was a signal from manufacturers to potential customer not just of some vauge picture quality performance level.  Broadcast grade was, in my experience working as video engineer in facilites using network grade equipment, also a promise from the manufacturers that their product does not violate federal regultaions (FCC rules).  And I'm talking here about the federal regulations (FCC rules) that were written by the NTSC.  The first broadcast grade studio equipment sold to the networks that contradicts FCC rules would indeed signal a switch in industry practice to evading federal law. Another reliable signal of a switch is in the broadcast grade picture monitors that dropped the matrix switch with the circuitry operation the same as the matrix switch in the off position.  My feeling at this time is that color space conversion from FCC primaries to actual physical screen primaries was always available in broadcast grade picture monitors.  Indeed, I purhased an Ikegami broadcast grade studio picture monitor in 1990.  It cost five-thousand 1990 dollars, had full I/Q demodulation, used SMPTE-C phosphors, and had the standard matrix switch the same as used on the Conrac monitors.  While at the NAB in 1990, I looked at many camera demos.  All the monitors used SMPTE-C phosphors with their matrix switches turned on, meaning the camera signal expected FCC phosphors (FCC primary colors).  So we need reliable references of an actual change in industry practice toward lawlessness.  Standards bodies may adopt standards, but that's not the same as industry following them in their entirety.  We should only point out the camera and monitor specifications along with any contradictions to engineering specs authored by the NTSC. My own feeling is that the industry was indeed law abiding, but I guess I could be wrong at some point.  Let's see the actual refernces of a shift in industry practice.  Remember also that signals not bound for local TV transmitter have no legal requirment to conform to ANY NTSC variant, FCC or otherwise, and so there was a market of cheaper TV equipment ("consumer", "semi-pro", "industrial" that made no pretenses to following ANYTHING, except to be "NTSC compatible".  And this is where a lot of confusion is coming from.  So we will leave it up the readers themselves to decide if people should have gone to jail. --Ohgddfp (talk) 14:39, 25 March 2009 (UTC)

text: Of course no one ever went to jail. That was pure hyperbole.  It was supposed to be a funny way to remind the talk page reader that the context was legal considerations. Ohgddfp (talk) 21:02, 18 May 2020 (UTC)

text: When I was young, and had a subscription to Popular Electronics, I remember a cartoon series based on FCC regulations and amateur radio, which might have included jail time.  The only one I can now remember (maybe 50 years later) is someone grounding their transmitter to a water faucet hanging out the window.  (That is, not in the ground or attached to anything in the ground.)  I suspect that if someone died due to a mistake, that jail could be considered. Gah4 (talk) 15:57, 12 May 2017 (UTC)
thread_title:  History 

message: In the Color Encoding section, the last paragraph uses the term "audio subcarrier"
several times. The audio has its own carrier, but intercarrier audio (which just
about every NTSC receiver had) uses one common IF amplifier chain for both
video and audio (at least, it did in tube days). Audio is recovered at 4.5 MHz
from the demodulated video, iirc, so, in a sense, at the demodulation stage, it's
akin to a subcarrier; however, this paragraph needs rewriting slightly, I think.
I didn't want to change it, because I'm not totally sure about what I believe to be true.
{For some reason, previewing this text as originally typed
rendered it on one quite-long line, requiring scrolling to read it.
I added line breaks.}
Regards, Nikevich (talk) 07:38, 24 November 2009 (UTC)
replies: text: About "audio subcarrier".  If, in transmission, you modulate the visual carrier with a frequency modulated 4.5 MHz audio subcarrier, along with the video itself, you separately get the AM visual carrier with sidebands containing picture information, plus an FM carrier with sidebands containing audio information.  The FM carrier on the air is 4.5 MHz higher than the visual carrier.  The original 4.5 MHz FM sound carrier (its sideband near 4.5 MHz), completely disappears on the air.  Although this process can work with extremely linear amplifiers, it is just not done for full power commercial TV transmitters, due to the perfection needed for amplifier linearity so that beats don't appear.  They instead use two separate transmitters, one for sound, the other for picture.  At the receiving end, whenever the entire TV signal is presented to the input of an AM detector, the detector output is the video signal, plus a frequency modulated 4.5 MHz audio subcarrier, even though no such 4.5 MHz carrier is ever on the air.  Older receivers in the forties would filter out the upper frequencies for the video channel, so that the AM detector was not presented with the full TV signal, but only those frequencies related to video.  As a result, no sound subcarrier was on the output of the AM detector.  Likewise, only the highest frequencies of the TV signal were presented to the input of an FM demodulator, which had only the sound signal as output.  In the intercarrier system, the entire TV signal, not just the video related frequencies, are presented to an AM detector, where the visual carrier is much stronger than the frequencies related to the sound.  As a result, the 4.5 MHz FM sound subcarrier with sidebands appears for the first time.  Note that this FM sound subcarrier (with sidebands) must still be presented to the input of an FM detector in order to recover the audio signal.  So "sound subcarrier" is legitimate, since it is physically indistinguishable from "4.5 MHz sound I.F." Ohgddfp (talk) 20:36, 1 February 2014 (UTC)
thread_title:  Audio subcarrier? Looks wrong. 

message: How come the early CBS system had 24 effective frames/sec but 144 fields/sec? Did it split each frame into 144 / 24 = 6 fields? That's the logical explanation to me, but the way it's written now, it seems a bit obscure and confusing, so the section would probably benefit from adding that fact if it's true. --79.193.57.210 (talk) 21:00, 8 June 2010 (UTC)
replies: text: It's true that the CBS analog system (briefly the law of the land--FCC) used 6 fields per frame. Ohgddfp (talk) 16:09, 6 January 2024 (UTC)
thread_title:  History: CBS system 

message: About this portion of the article: "The phase represents the instantaneous color hue captured by a TV camera, and the amplitude represents the instantaneous color saturation."
This is not completely true.
Below are some concepts that can help guide the search for more reliable sources of information to put into the article.
If only the chrominance signal (which is the MODULATED subcarrier with the subcarrier itself suppressed), is examined on a vectorscope, one can readibly see amplitude and phase for various colors.  But the amplitude provides zero quantifiable information on how much a given color is saturated.  ZERO.  At best, one can examine the NTSC spec and figure out that the acutal saturation of a given color, based only on what's seen on a vectorscope is within some VERY WIDE RANGE of possible saturations.  That's because it's the COMBINATION of the Y (brightness or monochrome) signal and the subcarrier amplitude that most determines the actual saturation.
And gamma must be taken into account as well.
Furthermore, hue often shifts noticibly when only the subcarrier amplitude is changed a great deal.  And we are talking IDEAL HARDWARE here.  The discrepencies are a mathematical consequence of the NTSC specifications, not hardware imperfections.
One of the things that can be said for sure is that an increase in subcarrier amplitude will cause an increase in saturation, provided that the color on the display screen is not already at the maximum saturation that the display screen primary colors can support.
So here's a better way to put this:  "Regarding the subcarrier, the phase represents the approximate instantaneous color hue, and the amplitude, COMBINED WITH THE EFFECTS OF THE Y SIGNAL, represents the approximate instantaneous color saturation. Ghidoekjf (talk) 22:49, 9 July 2010 (UTC)
thread_title:  Phase is Hue - Amplitude is Saturation -- Not quite 

message: About the article -  Technical Details --> Lines and refresh rate --> 2nd Paragraph, where it says
"Matching the field refresh rate to the power source avoided INTERMODULATION (also called beating), which produces rolling bars on the screen."
The problem is the term INTERMODULATION. Another problem is what happens to the "rolling bars" with the color system, since the field refresh is no longer matched to the 60Hz frequency of alternating current power.  Although some measure of intermodulation always occurs, and certainly a large measure of intermodulation occurs when the "rolling bars" are SEVERE, due to at minimum the non-linearity of the picture tube, intermodulation is NOT REQUIRED for producing a MILD "rolling bars" beat pattern.  And mild is certainly the most likely by far.  The example of "rolling bars" and beating was mentioned only for black and white, but not mentioned for color.  So I'll mentioned it here.  60Hz minus 59.94Hz = 0.06Hz, where 0.06Hz is the frequency of the beat pattern for color service.  Although the beats really do occur at the 0.06Hz rate, this does not mean there is a substantial 0.06Hz FREQUENCY COMPONENT when there is a "rolling bar" that takes 8 seconds to crawl from bottom to top.  The 0.06Hz "rolling bars" frequency component for color can only occur with intermodulation, and if there is no substantial degree of 0.06Hz component, then there is also no substantial intermodulation either in the case of MILD rolling bars.  Instead of intermodulation, the effect of MILD rolling bars is due almost entirely to simple LINEAR addition of the 60 or 120 Hz power supply ripple to the video signal. And intermodulation requires NON-LINEAR, not LINEAR combination.  So change the article to REMOVE the term INTERMODULATION, thereby improving the accuracy of the article. Ghidoekjf (talk) 16:19, 8 August 2010 (UTC)
replies: text: If the power supply filtering isn't so good then line frequency, or a multiple of line frequency, comes through into the video signal and is visible.  For this reason, the power supplies for color TV had to be better than previously needed for B&W only.  Though .06Hz is slow enough not to be so noticable.  Gah4 (talk) 04:34, 19 November 2010 (UTC)

text: Actually, intermodulation isn't the main problem.  The CRT is sensitive to external magnetic fields such as from nearby transformers or motors.  By making the frame rate equal to the power frequency, although the effect isn't eliminated, it as at least stationary and thus goes unnoticed.  The slight change of frame rate with the introduction of color ceased to be as serious a problem because the increase in accelerating voltage significantly decreased the sensitivity of the CRT to magnetic fields.  Thus the effect of external fields became far less noticeable.  A further improvement is obtained because color CRTs usually have a limited amount of magnetic shielding. 86.176.154.127 (talk) 18:10, 21 January 2011 (UTC)
replies: text: The external magnetic fields do not produce a moving shadow effect ("rolling bars").  Instead, they affect the scanning beam positioning as to bend the image slightly, and this bending effect moves vertically at the same rate as genuine "rolling bars".  Also, the ocsillating magnetic fields can cause rolling color impurity as well, also at the same rate as rolling bars.  But this issue is "rolling bars", which is a video shading effect, not affected by magnetic fields.  Bending can also happen if power supply ripple gets into video circuits ahead of the sync circuits.  It's the disturbance of those horizontal sync circuits that causes the geometric bending.  Therefore, magnetic field problems causing some distubance of some sort are limited to design issues of transformers too close.  In service, a failed automatic degausser circuit applies some degausing all the time, which is also a magnetic disturbance.  Conclusion: Magnetic fields are indeed the more difficult design issue, but with internal power transformer too close, not by external ocillating fields, except for a nearby vacuum cleaner motor.  The "rolling bars" are a video moving shadow effect, potentially a design or component failure issue equal to monochrome or color, although color TV's have a bigger power supply. Ohgddfp (talk) 04:40, 21 September 2012 (UTC)
thread_title:  Technical Details -- Power Supply Frequency and Intermodulation 

message: This section in the article looks very good.  I guess this is not really an edit. Ghidoekjf (talk) 16:29, 8 August 2010 (UTC)
thread_title:  Color correction in studio monitors and home receivers - Article is right on 

message: About -- Technical Details --> Color Encoding --> 3rd paragraph (towards end), where it says,
"This process of discretization necessarily degrades the picture information somewhat, ..."
 
This is not true.
Here is what I expect to be found from a good source.  Transferring back and forth between discrete samples and a continuous signal is a LOSSLESS operation. Of course, any kind of operation done in a sloppy manner will cause degradation, but that's true for ANY operation.  That means it's POSSIBLE for the analog tuner section of a modern flat panel LCD receiver to recover the original pixels from a modern video camera imager, all within the NTSC standard for low power analog transmissions still on the air.  Here's how it would work, just as an example to illustrate the concept.  Use a video camera with a hypothetical 448x483 imager. ("rectangular pixels"). The imager samples are processed into a composite video signal at the same sample rate (different from subcarier).  The pixels now also contain the subcarrier sidebands (chroma).  Then low-pass filter (flat within the entire video band) so that indeed the horizontal pixels are blended into continuous lines, then transmitted, and received.  The analog tuner section of the receiver resamples at the same rate, using burst as the clock input to a sample reference generator, where the sample reference is different (and higher) compared to the subcarrrier frequency.  There are other details that need to be insured, but still within FCC NTSC specs.  The result is a complete and exact replication of the original camera pixels as far as black and white movies are concerned. The exactness limited only by practical hardware, not the NTSC standard.  For color video, color difference information is still bandwidth limited and other NTSC artifacts are also still intact.  Of course inside HD displays, a digital resample and upconversion is needed.  Sorry, no additional resolution or picture definition by upconverting NTSC to HD.
So discretization, whether the vertical scanning lines of NTSC, or both vertical and horizontal for digital TV, does not necessarily cause picture quality degradation.
Recommend to simply remove the article phrase containing the word "degrades". Ghidoekjf (talk) 17:33, 8 August 2010 (UTC)
thread_title:  Color Encoding -- Discretization 

message: About - Comparative quality --> 1st paragraph, where it says, "Reception problems can degrade an NTSC picture by changing the phase of the color signal (actually differential phase distortion), ..."
The problem is equating "differential phase distortion" with "reception problems". "Reception problems" sounds like issues that occur in the air between the transmit and receive antennas.  
But "through the air" reception problems are limited to 1) Signal that is too weak.  2) Interfering signals linearly added to the desired signal, and 3) Multipath.
Multipath, which alters the reception strength (amplitude) versus frequency and the phase versus frequency, and sometimes also nulls out some frequencies, is a form of LINEAR distortion, and is caused by obstacles and reflections in the signal path from transmit antenna to receive antenna. Differential phase distortion on the other hand is NON-LINEAR, and so cannot happen in the air.  It happens mostly in older TV transmitters, and also in poorly designed TV receivers near overload condition.
So a transmitter defect (differential phase distoriton) is not really a "reception problem" at all as the article implies.   And an overloaded tuner (from a strong signal) is not the fault of reception conditions either.  Certainly a signal that is very strong is not thought of as a reception problem.
What can be said is that NTSC is more visually sensitive than PAL to both differential phase distortion and to multipath.  With NTSC, multipath can produce additional hues not present in the original. Ghidoekjf (talk) 21:39, 8 August 2010 (UTC)
replies: text: So how do you explain the shift in phase of the hue vector between different stations on reception?  All the colors of similar luminance shift by the same phase shift which can only be explained by differential phase distortion. 86.176.154.127 (talk) 18:03, 21 January 2011 (UTC)
replies: text: About "shift in phase of the hue vector ...":  There is no such thing as "shift in phase of the hue vector".  Phase is a comparison between two signals.  With NTSC, the two signals are 1)The reconstructed subcarrier inside the receiver, made from the "burst" portion of the incoming signal, and 2) The "chrominance" portion of the "active" video signal.  Between 1) and 2) above, sometimes the phase relationship between those two signals are different between multiple stations broadcasting the same program, and I think this is what you are asking about.  The cause is mostly improper technical operation at one or both TV stations.  Some of the cause can be differential phase problems ( a form of non-linear distortion), most of which is in some videotape playback and some transmitters to some hopefully small degree.  It can also occur if one or more of the received stations is onverloading the tuner because the signal is too strong.  It can never occur in the air.
 Ohgddfp (talk) 17:13, 13 September 2012 (UTC)
thread_title:  Comparative quality - Differential Phase Cannot happen as a Reception Problem 

message: In the SECAM article (and in other publications, such as the WRTH), Vietnam is always shown as having both SECAM and NTSC used for colour TV - the SECAM article says it is "simulcast with NTSC-M".  Presumably, NTSC is used in the former South Vietnam and SECAM in the former North Vietnam.  So why is there no mention of it in the NTSC article? --108.12.198.48 (talk) 01:33, 31 July 2011 (UTC)
thread_title:  Where's Vietnam in the list of countries? 

message: Is it really accurate to say that most of South America used the NTSC system? While it seems that the majority of south American countries adopted the standard, the map shows that geographically the majority was PAL. Did the majority of viewers on the continent receive NTSC? (My apologies if this has been raised before; I haven't read through the entire talk page) Stanstaple (talk) 18:59, 16 August 2011 (UTC)
thread_title: South America

message: There were no colour tests in Ireland using NTSC on 405 lines at all. Suggest the link to Ireland is removed. Donoreavenue (talk) 00:19, 20 May 2012 (UTC)
replies: text: Are you sure ? The BBC and IBA were experimenting with NTSC as late as 1965. Its possible that engineers in RTE (who were following developments in Britain very closely) were carrying out their own tests ? 94.2.188.218 (talk) 18:50, 5 August 2015 (UTC)
thread_title: Ireland

message: About "This process of discretization necessarily degrades the picture information somewhat, though with small enough pixels the effect may be imperceptible.":  Where is the source?  We need to find a reliable source for this.  Otherwise, I will delete the above quote from the article.  Or, ....... not.  So here's my argument.  From sources on this subject over the years, I've found that discretization is a lossless process, meaning that, unlike that for many other kinds of operations where mathematically, there exists a minimum degree of degradation, discretization has no such minimum degree of degradation.  In other words, with discretization, as with many other kinds of signal processing, there is no mathematical limitation as to how small the degradation can be.
  
So in NTSC, degradation caused by discretization can be minimized to any desired degree through hardware improvements.  But that can be said about almost all operations.   So why single out discretization?   This is not an NTSC problem in reality.  It gives weight to something that, due to hardware imperfections, is no worse than just about any other signal processing operation.  Giving such weight to something without a good source to back it up only confuses the reader.  Since this is actually in the realm of mathematics, I am waiting for a mathematical proof from a reliable source, that discretization "necessarily degrades the picture information somewhat".  Since this is a mathematical issue, the source must be compatible with mainstream science.
- A source, anyone? Ohgddfp (talk) 02:06, 13 December 2013 (UTC)
replies: text: From Nyquist–Shannon_sampling_theorem if you sample a band-limited signal with a sample rate greater than twice the bandwidth, no information is lost. Video sources are normally band limited, so this should not be a problem.  Actually Nyquist sampling requires that the signal be available over an infinite time span, but it is plenty close enough for usual video and audio sources.  The loss comes later, when MPEG compression is done to the sampled signal.  In signal processing, there is also quantization, relating to the finite number of values at each sample point.  With uniform sample spacing, this results in quantization noise with amplitude about half the quantization step. Quantization noise is fundamental in any digital system, but can usually be made low enough, compared with other noise sources, such as thermal noise. Gah4 (talk) 16:59, 12 May 2017 (UTC)

text: Yes, digitization always causes quantization noise, which indeed is a degradation of the picture information. Hopefully such degradation banding is not usually noticable.  Now discretization, required by digital systems, also occurs in some analog systems where the signal is sampled, but not digitized.  This is sampled analog.  There are some video tape time-base correctors (used for color under VCRs inside cable TV studios--I myself used them--that are this kind of sampled analog, using analog memory cells in a fire bucket delay arrangment. So sampled (discretization) analog degrades only by hardware imprefections, as any operation in analog is degraded by hardware inperfection.  Analog disretization has no inherent picture information degradation at all. Ohgddfp (talk) 16:39, 6 January 2024 (UTC)
thread_title:  Upcoming Fix - Discretization 

message: According to , China uses PAL D, not NTSC. I also have a old Sharp chart showing the system of the World showing the same thing. I would like to propose that China be moved from NTSC to PAL. RAM (talk) 02:22, 6 March 2014 (UTC)
replies: text: Taiwan seems to be on the list of countries that switched away from NTSC, but not on the list of countries using, or previously using, NTSC.  According to the one China policy, Taiwan is part of China, so should China be back on? Gah4 (talk) 17:03, 12 May 2017 (UTC)
thread_title: China uses PAL, not NTSC

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thread_title:  External links modified 

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thread_title:  External links modified 

message: * Statement about PAL-N: Greater number of lines results in higher quality.
Would be worth to have a comment on this from someone who actually has seen a PAL-N transmission. But TV engineers believe that PAL-N is no better than PAL-M because the video bandwith is limited to 4.2 MHz as well. And in fact it is still used only in Argentina and Paraguay, with all analogue transmitters in Uruguay already being closed.
* Statement about NTSC 4.43: The format was used by the USAF TV based in Germany during the Cold War.[citation needed]
AFN TV transmitters in Germany used video carrier frequencies in accordance with the European "E" channels. But the video itself was standard NTSC-M and not some oddball. Audio was 4.5 MHz above video carrier as well. I have never seen any other information than this. Thus I think that the statement here is very likely incorrect, apparently reflecting confusion from the use of NTSC-M in the "E" channel spacing. The Cold War reference also needs to be removed. The last AFN TV transmitters in Germany have been closed only a few years ago, probably even outliving any PAL-B/G transmitters (I would have to check out the timeline in detail to see if indeed NTSC was in Germany still on air when PAL was already gone).
* Paraguay (switched to PAL-N in 2005)
The 1994 edition of World Radio TV Handbook already shows PAL-N for Paraguay (p. 427). For all I know Paraguay used always the "N" system, i.e. 625/50 with 4.2 MHz video bandwith, and started colour TV outright with PAL-N, like the other two "N" countries who earlier choose to use 625/50 but had to observe the 4.2 MHz video bandwith restriction, imposed by the American 6 MHz channel spacing.
--2003:45:4547:4A33:215D:377A:8F93:CD21 (talk) 11:45, 11 September 2016 (UTC)
thread_title:  PAL-N, AFN transmitters in Germany, Paraguay 

message: I've seen NTSC as an acronym for "National Television System Committee", but somewhere I read it was National Television Standards Committee. Is it possible that the latter was also used, or that it became one or the other over time? Misty MH (talk) 08:14, 5 January 2017 (UTC)
replies: text: The NTSC called themselves the "National Television System Committee".  It was never officially changed to anything else. See their 1953 publication: "Petition of National Television System Committee for Adoption of Transmission Standards for Color Television". This can be found in Google Books. Ohgddfp (talk) 16:50, 6 January 2024 (UTC)
thread_title:  NTSC definition of the acronym 

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I have just modified 6 external links on NTSC. Please take a moment to review my edit. If you have any questions, or need the bot to ignore the links, or the page altogether, please visit this simple FaQ for additional information. I made the following changes:
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thread_title:  External links modified (February 2018) 

message: It may not seem too consequential, but there are BIG differences between the original RS-170 and RS-170a - this should be mentioned in the variants
* EIA RS-170 is a black/white only spec that was widely used in closed circuit TV systems and for industrial apps and is based on the original 1946 spec modified in 1950.
** RS-330 is an industrial spec based on RS-170 that uses standard scan rates that was defined in 1966
** RS-343 is an industrial spec based on RS-170 modified for higher scan rates that was defined in 1967
* RS-170a was an upgraded spec from 1953 that was considered backwards compatible and designed to allow a compatible color system. This is what people generally call NTSC. The addition of the color burst signal on the back porch in the days of vacuum tube circuitry required extensive engineering support to transmit a good signal. Before the days of digital sync generators the timing signals were generated using monostable multivibrator timing circuits whose timing would drift as components aged and temperatures changed.
:: People may be calling RS-170a an "upgraded version" of NTSC, but it was never official with the NTSC itself, nor with the Federal Communication Commission, and this should be made plain.  Part of RS-170a was implemented by broadcasters for the purpose of frame-match editing with video tape recorders and does not contradict NTSC-FCC standards.  Color fidelity took a hit after 1962 when receivers used the more energy efficient but different colored phosphors.  Eventually, some broadcasters could in theory have utilized cameras with RS170a colorimetry that would have brought color fidelity back up to 1953 performance levels for those 1960's TV receivers.  The color gamuts of FCC-NTSC on the one hand and the color gamuts of RS170a are actually different, and should be considered different non-compatible standards as far as colorimetry is concerned.  Indeed, broadcast monitors after 1962 used the newer phosphors and electronically partially corrected for an NTSC (not RS170a) signal when the "Matrix" switch on the monitor was turned on.  Receivers did the same. Ohgddfp (talk) 19:55, 3 June 2021 (UTC)
thread_title:  RS-170 vs RS-170a  or black&white vs color