Editing NTSC (section)

== History ==
{{See also|History of television}}

The National Television System Committee was established in 1940 by the United States [[Federal Communications Commission]] (FCC) to resolve the conflicts between companies over the introduction of a nationwide analog television system in the United States. In March 1941, the committee issued a technical standard for black-and-white television that built upon a 1936 recommendation made by the Radio Manufacturers Association (RMA). Technical advancements of the [[Single-sideband modulation#Vestigial sideband (VSB)|vestigial side band]] technique allowed for the opportunity to increase the image resolution. The NTSC selected 525&nbsp;scan lines as a compromise between [[RCA]]'s [[441-line television system#United States|441-scan line]] standard (already being used by RCA's [[NBC]] TV network) and [[Philco]]'s and [[DuMont Television Network|DuMont]]'s desire to increase the number of scan lines to between 605 and 800.<ref>What actually occurred was the RCA TG-1 synch generator system was upgraded from 441 lines per frame, 220.5 lines per field, interlaced, to 525 lines per frame 262.5 lines per field, also interlaced, with minimal additional changes, particularly not those affecting the vertical interval, which, in the extant RCA system, included serrated equalizing pulses bracketing the vertical sync pulse, itself being serrated. For RCA/NBC, this was a ''very'' simple change from a 26,460&nbsp;Hz master oscillator to a 31,500&nbsp;Hz master oscillator, and minimal additional changes to the generator's divider chain. The equalizing pulses and the serration of the vertical sync pulse were necessary because of the limitations of the extant TV receiver video/sync separation technology, thought to be necessary because the sync was transmitted in band with the video, although at a quite different DC level. The early TV sets did not possess a DC restorer circuit, hence the need for this level of complexity. In-studio monitors were provided with separate horizontal and vertical sync, not composite synch and certainly not in-band synch (possibly excepting early color TV monitors, which were often driven from the output of the station's [[colorplexer]]).{{Citation needed|date=April 2024}}</ref> The standard recommended a [[frame rate]] of 30 frames (images) per second, consisting of two [[interlaced video|interlace]]d [[field (video)|fields]] per frame at 262.5&nbsp;lines per field and 60&nbsp;fields per second. Other standards in the final recommendation were an [[Aspect ratio (image)|aspect ratio]] of 4:3, and frequency modulation (FM) for the sound signal (which was quite new at the time).

In January 1950, the committee was reconstituted to standardize [[color television]]. The FCC had briefly approved a [[405-line television system#United States 405-line field-sequential color system|405-line]] [[Field-sequential color system|field-sequential]] color television standard in October 1950, which was developed by [[CBS]].<ref>A third line sequential system from [[Color Television Inc.]] (CTI) was also considered. The CBS and final NTSC systems were called field-sequential and dot-sequential systems, respectively.</ref> The CBS system was incompatible with existing black-and-white receivers. It used a rotating color wheel, reduced the number of [[scan line]]s from 525 to 405, and increased the field rate from 60 to 144, but had an effective [[frame rate]] of only 24 frames per second. Legal action by rival RCA kept commercial use of the system off the air until June 1951, and regular broadcasts only lasted a few months before manufacture of all color television sets was banned by the [[Office of Defense Mobilization]] in October, ostensibly due to the [[Korean War]].<ref>{{cite news |date=October 20, 1951 |title=Color TV Shelved As a Defense Step |work=[[The New York Times]] |page=1}}</ref><ref>{{cite news |date=October 22, 1951 |title=Action of Defense Mobilizer in Postponing Color TV Poses Many Question for the Industry |work=[[The New York Times]] |page=23}}</ref><ref>{{cite news |date=October 26, 1951 |title=TV Research Curb on Color Avoided |work=[[The New York Times]]}}</ref><ref>{{cite web |author=Ed Reitan |year=1997 |title=CBS Field Sequential Color System |url=http://novia.net/~ereitan/Color_Sys_CBS.html |archive-url=https://web.archive.org/web/20100105183213/http://novia.net/~ereitan/Color_Sys_CBS.html |archive-date=January 5, 2010}}</ref> A variant of the CBS system was later used by [[NASA]] to broadcast pictures of astronauts from space.{{Citation needed|date=April 2024}} CBS rescinded its system in March 1953,<ref>{{cite news |date=March 26, 1953 |title=CBS Says Confusion Now Bars Color TV |newspaper=[[The Washington Post]] |page=39}}</ref> and the FCC replaced it on December 17, 1953, with the NTSC color standard, which was cooperatively developed by several companies, including RCA and Philco.<ref>{{cite news |date=December 19, 1953 |title=F.C.C. Rules Color TV Can Go on Air at Once |work=[[The New York Times]] |page=1}}</ref>

In December 1953, the FCC unanimously approved what is now called the ''NTSC'' color television standard (later defined as RS-170a). The compatible color standard retained full backward compatibility with then-existing black-and-white television sets. Color information was added to the black-and-white image by introducing a color [[subcarrier]] of precisely 315/88&nbsp;MHz (usually described as 3.579545&nbsp;MHz±10&nbsp;Hz).<ref name="73.682">{{cite web |title=73.682 |url=https://www.govinfo.gov/content/pkg/CFR-2018-title47-vol4/pdf/CFR-2018-title47-vol4-sec73-682.pdf |access-date=January 22, 2019 |website=Govinfo.gov |publisher=FCC}}</ref> The precise frequency was chosen so that horizontal line-rate modulation components of the chrominance signal fall exactly in between the horizontal line-rate modulation components of the luminance signal, such that the chrominance signal could easily be filtered out of the luminance signal on new television sets, and that it would be minimally visible in existing televisions. Due to limitations of [[frequency divider]] circuits at the time the color standard was promulgated, the color subcarrier frequency was constructed as composite frequency assembled from small integers, in this case 5×7×9/(8×11)&nbsp;MHz.<ref>The master oscillator is 315/22 = 14.31818&nbsp;MHz, from which the 3.579545 color burst frequency is obtained by dividing by four; and the 31&nbsp;kHz horizontal drive and 60&nbsp;Hz vertical drive are also synthesized from that frequency. This facilitated a conversion to color of the then common, but monochrome, RCA TG-1 synchronizing generator by the simple expedient of adding-on an external 14.31818&nbsp;MHz temperature-controlled oscillator and a few dividers, and inputting the outputs of that chassis to certain test points within the TG-1, thereby disabling the TG-1's own 31500&nbsp;Hz reference oscillator.{{Citation needed|date=April 2024}}</ref> The horizontal line rate was reduced to approximately 15,734 lines per second (3.579545&nbsp;× 2/455&nbsp;MHz&nbsp;= 9/572&nbsp;MHz) from 15,750 lines per second, and the frame rate was reduced to 30/1.001&nbsp;≈ 29.970 frames per second (the horizontal line rate divided by 525 lines/frame) from 30 frames per second. These changes amounted to 0.1 percent and were readily tolerated by then-existing television receivers.<ref>{{cite journal |last1=Abrahams |first1=I.C. |date=1954 |title=Choice of Chrominance Subcarrier Frequency in the NTSC Standards |journal=[[Proceedings of the IRE]] |volume=42 |issue=1 |pages=79–80 |doi=10.1109/JRPROC.1954.274612}}</ref><ref>{{cite journal |last1=Abrahams |first1=I.C |title=The Frequency Interleaving Principle in the NTSC Standards |journal=[[Proceedings of the IRE]] |volume=42 |issue=1 |pages=81–83 |doi=10.1109/JRPROC.1954.274613}}</ref>

The first publicly announced network television broadcast of a program using the NTSC "compatible color" system was an episode of NBC's ''[[Kukla, Fran and Ollie]]'' on August 30, 1953, although it was viewable in color only at the network's headquarters.<ref>"NBC Launches First {{Sic|?|hide=y|Publicly|-}}Announced Color Television Show", ''Wall Street Journal'', August 31, 1953, p. 4.</ref> The first nationwide viewing of NTSC color came on the following January 1 with the coast-to-coast broadcast of the [[Rose Parade|Tournament of Roses Parade]], viewable on prototype color receivers at special presentations across the country. The first color NTSC [[Professional video camera|television camera]] was the [[RCA TK-40/41|RCA TK-40]], used for experimental broadcasts in 1953; an improved version, the TK-40A, introduced in March 1954, was the first commercially available color television camera. Later that year, the improved TK-41 became the standard camera used throughout much of the 1960s.<!-- This lacks information about the first color broadcasts viewable on generally-available TV sets. Also, the jump from the introduction of color and standard adoption to phase-out is quite jarring and makes no mention of time passed. -->

The NTSC standard has been adopted by other countries, including some in the [[Americas]] and [[Japan]].