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The National Television System Committee (NTSC)National Television System Committee (1951–1953), Report and Reports of Panel No. 11, 11-A, 12-19, with Some supplementary references cited in the Reports, and the Petition for adoption of transmission standards for color television before the Federal Communications Commission, n.p., 1953], 17 v. illus., diagrs., tables. 28 cm. LC Control No.:5402138
Library of Congress Online Catalog
/ref> developed the
analog television Analog television is the original television Television (TV), sometimes shortened to tele or telly, is a telecommunication medium used for transmitting moving images in monochrome (black and white), or in color, and in two or three ...
color system that was introduced in North America in 1954 and stayed in use until digital conversion. It is one of three major analog color television standards, the others being
PAL 300px, upright=1.2, Analog television encoding systems by nation; SECAM.html"_;"title="NTSC_(green),_SECAM">NTSC_(green),_SECAM_(orange),_and_PAL_(blue). Phase_Alternating_Line_(PAL)_is_a_colour_encoding_system_for_Analog_television.html" ;"ti ...
and
SECAM 300px, upright=1.2, Analog television encoding systems by nation; NTSC (green), SECAM (orange), and PAL (blue).">PAL.html" ;"title="NTSC (green), SECAM (orange), and PAL">NTSC (green), SECAM (orange), and PAL (blue). SECAM, also written SÉ ...

SECAM
. All the countries using NTSC are currently in the process of conversion, or have already converted to the
ATSC Advanced Television Systems Committee (ATSC) standards are an American set of standards for digital television Digital television (DTV) is the transmission of television audiovisual Audiovisual (AV) is electronic media possessing both a so ...

ATSC
standard, or to DVB,
ISDB Integrated Services Digital Broadcasting (ISDB; Japanese Japanese may refer to: * Something from or related to Japan , image_flag = Flag of Japan.svg , alt_flag = Centered deep red circle on a white ...
or
DTMB DTMB (Digital Terrestrial Multimedia Broadcast) is the digital TV standard for mobile and fixed devices, developed in the China, People's Republic of China. It is used there and in both of their special administrative regions (Hong Kong and Macau) ...
. This page primarily discusses the NTSC color encoding system. The articles on
broadcast television systems Broadcast programming, Broadcast television systems (or terrestrial television systems outside the US and Canada) are the encoding or formatting standards for the transmission and reception of terrestrial television signals. There were three main ...
and analog television further describe
frame rate Frame rate (expressed in or FPS) is the frequency Frequency is the number of occurrences of a repeating event per unit of time A unit of time is any particular time Time is the indefinite continued sequence, progress of existence an ...
s,
image resolution Image resolution is the detail an image An image (from la, imago) is an artifact that depicts visual perception Visual perception is the ability to interpret the surrounding environment Environment most often refers to: __NOTOC_ ...
, and audio modulation. NTSC video is
composite video Composite video is an analog video Video is an electronic Electronic may refer to: *Electronics Electronics comprises the physics, engineering, technology and applications that deal with the emission, flow and control of electro ...

composite video
because the
luminance Luminance is a photometricPhotometry can refer to: * Photometry (optics), the science of measurement of visible light in terms of its perceived brightness to human vision * Photometry (astronomy), the measurement of the flux or intensity of an ...
(luma, monochrome image) and
chrominance Chrominance (''chroma'' or ''C'' for short) is the signal used in video systems to convey the color information of the picture, separately from the accompanying Luma (video), luma signal (or Y' for short). Chrominance is usually represented as two ...
(chroma, color applied to the monochrome image) are transmitted together as one signal. Often, the
480i 480i is the video Video is an electronic Electronic may refer to: *Electronics Electronics comprises the physics, engineering, technology and applications that deal with the emission, flow and control of electrons in vacuum and matt ...
(480 interlaced horizontal lines) video format is synonymous with NTSC video.


Geographic reach

The NTSC standard was used in most of the
Americas The Americas (also collectively called America) is a landmass comprising the totality of North America, North and South America. The Americas make up most of the land in Earth's Western Hemisphere and comprise the New World. Along with th ...

Americas
(except
Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country located mostly in the southern half of South America South America is a continent A continent is any of several large landmasse ...
,
Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At 8.5 million square kilometers (3.2 million square miles) and with over 211 mill ...
,
Paraguay Paraguay (; ), officially the Republic of Paraguay ( es, República del Paraguay, links=no; gn, Tetã Paraguái, links=no), is a country in South America South America is a entirely in the and mostly in the , with a relatively sma ...
, and
Uruguay Uruguay (; ; pt, Uruguai), officially the Oriental Republic of Uruguay ( es, República Oriental del Uruguay), is a country in South America. It shares borders with Argentina to its west and southwest and Brazil to its north and northeast; whi ...
),
Liberia Liberia (), officially the Republic of Liberia, is a country on the West Africa West Africa or Western Africa is the westernmost region of Africa. The United Nations defines Western Africa as the 17 countries of Benin, Burkina Faso, Cape ...

Liberia
,
Myanmar Myanmar, ); UK pronunciations: US pronunciations incl. . Note: Wikipedia's IPA conventions require indicating /r/ even in British English although only some British English speakers pronounce r at the end of syllables. As John C. Wells, John ...
,
South Korea South Korea, officially the Republic of Korea (ROK), is a country in East Asia, constituting the southern part of the Korea, Korean Peninsula and sharing a Korean Demilitarized Zone, land border with North Korea. Its western border is for ...
,
Taiwan Taiwan, officially the Republic of China (ROC), is a country in East Asia East Asia is the eastern region of Asia Asia () is Earth's largest and most populous continent, located primarily in the Eastern Hemisphere, Eastern and N ...
,
Philippines The Philippines (; fil, Pilipinas, links=no), officially the Republic of the Philippines ( fil, Republika ng Pilipinas, links=no), * bik, Republika kan Filipinas * ceb, Republika sa Pilipinas * cbk, República de Filipinas * hil, Republ ...
,
Japan Japan ( ja, 日本, or , and formally ) is an island country An island country or an island nation is a country A country is a distinct territory, territorial body or political entity. It is often referred to as the land of an in ...
, and some
Pacific Islands This is a list of islands in the Pacific Ocean, collectively called the Pacific Islands. Three major groups of island An island (or isle) is an isolated piece of habitat that is surrounded by a dramatically different habitat, such as ...
nations and territories (see map).


Digital conversion

Most countries using the NTSC standard, as well as those using other analog television standards, have switched to, or are in process of switching to, newer
digital television Digital television (DTV) is the transmission of television audiovisual Audiovisual (AV) is electronic media 200px, Graphical representations of electrical audio data. Electronic media uses either analog (red) or digital (blue) signal pr ...
standards, with there being at least four different standards in use around the world. North America, parts of
Central America Central America ( es, América Central, , ''Centroamérica'' ) is a region of the Americas The Americas (also collectively called America) is a landmass comprising the totality of North North is one of the four compass points or ...

Central America
, and
South Korea South Korea, officially the Republic of Korea (ROK), is a country in East Asia, constituting the southern part of the Korea, Korean Peninsula and sharing a Korean Demilitarized Zone, land border with North Korea. Its western border is for ...

South Korea
are adopting or have adopted the ATSC standards, while other countries, such as
Japan Japan ( ja, 日本, or , and formally ) is an island country An island country or an island nation is a country A country is a distinct territory, territorial body or political entity. It is often referred to as the land of an in ...

Japan
, are adopting or have adopted other standards instead of ATSC. After nearly 70 years, the majority of over-the-air NTSC transmissions in the United States ceased on January 1, 2010, and by August 31, 2011,DTV and Over-the-Air Viewers Along U.S. Borders
FCC.gov. Retrieved on 2014-05-11.
in
Canada Canada is a country in the northern part of North America North America is a continent A continent is any of several large landmasses. Generally identified by convention (norm), convention rather than any strict criteria, ...

Canada
and most other NTSC markets.Canada... PAL or NTSC?
VideoHelp Forum Retrieved on 2015-01-23.
The majority of NTSC transmissions ended in Japan on July 24, 2011, with the Japanese prefectures of Iwate, Miyagi, and
Fukushima may refer to: Japan * Fukushima Prefecture Fukushima Prefecture (; ja, 福島県, Fukushima-ken, ) is a Prefectures of Japan, prefecture of Japan located in the Tōhoku region of Honshu. Fukushima Prefecture has a population of 1,848,257 ( ...
ending the next year. After a pilot program in 2013, most full-power analog stations in Mexico left the air on ten dates in 2015, with some 500 low-power and repeater stations allowed to remain in analog until the end of 2016. Digital broadcasting allows higher-resolution television, but digital standard definition television continues to use the frame rate and number of lines of resolution established by the analog NTSC standard.


History

The first NTSC standard was developed in 1941 and had no provision for color. In 1953, a second NTSC standard was adopted, which allowed for
color television Color television is a television Television, sometimes shortened to TV or telly, is a telecommunication Telecommunication is the transmission of information by various types of technologies over wire A wire is a single usual ...
broadcasting which was compatible with the existing stock of
black-and-white Black-and-white (B/W or B&W) images combine black and white in a continuous spectrum In physics Physics (from grc, φυσική (ἐπιστήμη), physikḗ (epistḗmē), knowledge of nature, from ''phýsis'' 'nature'), , is ...
receivers. NTSC was the first widely adopted broadcast color system and remained dominant until the 2000s, when it started to be replaced with different
digital Digital usually refers to something using digits, particularly binary digits. Technology and computing Hardware *Digital electronics Digital electronics is a field of electronics Electronics comprises the physics, engineering, technology a ...
standards such as
ATSC Advanced Television Systems Committee (ATSC) standards are an American set of standards for digital television transmission over terrestrial, cable and satellite networks. It is largely a replacement for the analog NTSC standard and, like that ...
and others. The National Television System Committee was established in 1940 by the United States
Federal Communications Commission The Federal Communications Commission (FCC) is an independent agency A regulatory agency or regulatory authority, is a Public benefit corporation Public-benefit corporation is a term that has different meanings in different jurisdictions. I ...
(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 vestigial side band technique allowed for the opportunity to increase the image resolution. The NTSC selected 525 scan lines as a compromise between
RCA The RCA Corporation was a major American electronics company, which was founded as the Radio Corporation of America in 1919. It was initially a patent trust owned by General Electric General Electric Company (GE) is an American multinatio ...
's 441-
scan line A scan line (also scanline) is one line, or row, in a raster scan A raster scan, or raster scanning, is the rectangular pattern of image capture and reconstruction in television. By analogy, the term is used for raster graphics file:Rgb-raste ...
standard (already being used by RCA's
NBC The National Broadcasting Company (NBC) is an American American(s) may refer to: * American, something of, from, or related to the United States of America, commonly known as the United States The United States of America (USA), co ...
TV network) and
Philco Philco (founded as Helios Electric Company, renamed Philadelphia Storage Battery Company) was a pioneer in battery, radio, and television production. In 1961 the company was purchased by Ford The Ford Motor Company, commonly known as Ford, ...
's and DuMont's desire to increase the number of scan lines to between 605 and 800. The standard recommended a
frame rate Frame rate (expressed in or FPS) is the frequency Frequency is the number of occurrences of a repeating event per unit of time A unit of time is any particular time Time is the indefinite continued sequence, progress of existence an ...
of 30 frames (images) per second, consisting of two interlaced
fields File:A NASA Delta IV Heavy rocket launches the Parker Solar Probe (29097299447).jpg, FIELDS heads into space in August 2018 as part of the ''Parker Solar Probe'' FIELDS is a science instrument on the ''Parker Solar Probe'' (PSP), designed to mea ...
per frame at 262.5 lines per field and 60 fields per second. Other standards in the final recommendation were an
aspect ratio The aspect ratio of a geometric Geometry (from the grc, γεωμετρία; '' geo-'' "earth", '' -metron'' "measurement") is, with arithmetic, one of the oldest branches of mathematics. It is concerned with properties of space that are ...
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 Color television is a television Television, sometimes shortened to TV or telly, is a telecommunication Telecommunication is the transmission of information by various types of technologies over wire A wire is a single usual ...
. The FCC had briefly approved a color television standard in October 1950, which was developed by
CBS CBS is an American American(s) may refer to: * American, something of, from, or related to the United States of America, commonly known as the United States The United States of America (USA), commonly known as the United States (U.S ...

CBS
. The CBS system was incompatible with existing black-and-white receivers. It used a rotating color wheel, reduced the number of
scan line A scan line (also scanline) is one line, or row, in a raster scan A raster scan, or raster scanning, is the rectangular pattern of image capture and reconstruction in television. By analogy, the term is used for raster graphics file:Rgb-raste ...
s from 525 to 405, and increased the field rate from 60 to 144, but had an effective
frame rate Frame rate (expressed in or FPS) is the frequency Frequency is the number of occurrences of a repeating event per unit of time A unit of time is any particular time Time is the indefinite continued sequence, progress of existence an ...
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 MobilizationThe Office of Defense Mobilization (ODM) was an independent agency of the United States The United States of America (USA), commonly known as the United States (U.S. or US), or America, is a country Contiguous United States, primarily locate ...
in October, ostensibly due to the
Korean War The Korean War (see § Names) was a war fought between North Korea North Korea, officially the Democratic People's Republic of Korea (DPRK), is a country in East Asia, constituting the northern part of the Korean Peninsula. It b ...

Korean War
. CBS rescinded its system in March 1953, 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. 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 A subcarrier is a sideband , fm is the maximum modulation frequency In radio Radio is the technology of signaling and telecommunication, communicating using radio waves. Radio waves are electromagnetic waves of frequency between 30 her ...
of precisely 315/88 MHz (usually described as 3.579545 MHz±10 Hz or about 3.58 MHz). 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, thereby enabling the chrominance signal to be filtered out of the luminance signal with minor degradation of the luminance signal. (Also, minimize the visibility on existing sets that do not filter it out.) Due to limitations of
frequency divider A frequency divider, also called a clock divider or scaler or prescaler, is a circuit that takes an input signal of a frequency, f_, and generates an output signal of a frequency: : f_ = \frac where n is an integer. Phase-locked loop frequen ...
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) MHz. The horizontal line rate was reduced to approximately 15,734 lines per second (3.579545×2/455 MHz = 9/572 MHz) from 15,750 lines per second, and the frame rate was reduced to 30/1.001 ≈ 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. 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 ''Kukla, Fran and Ollie'' is an early American television show Image:MDR Kripo live.jpg, upright=1.35, A live television show set and cameras A television show – or simply TV show – is any content produced for viewing on a television set whi ...
'' on August 30, 1953, although it was viewable in color only at the network's headquarters. The first nationwide viewing of NTSC color came on the following January 1 with the coast-to-coast broadcast of the
Tournament of Roses Parade A tournament is a competition involving 4 or more teams, or a large number of competitors, all participating in a sport or game. More specifically, the term may be used in either of two overlapping senses: # One or more competitions held at a sing ...
, viewable on prototype color receivers at special presentations across the country. The first color NTSC
television camera A professional video camera (often called a television camera even though its use has spread beyond television Television (TV), sometimes shortened to tele or telly, is a telecommunication medium used for transmitting moving images in m ...
was the 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. The NTSC standard has been adopted by other countries, including most of the
Americas The Americas (also collectively called America) is a landmass comprising the totality of North America, North and South America. The Americas make up most of the land in Earth's Western Hemisphere and comprise the New World. Along with th ...

Americas
and
Japan Japan ( ja, 日本, or , and formally ) is an island country An island country or an island nation is a country A country is a distinct territory, territorial body or political entity. It is often referred to as the land of an in ...

Japan
. With the advent of
digital television Digital television (DTV) is the transmission of television audiovisual Audiovisual (AV) is electronic media 200px, Graphical representations of electrical audio data. Electronic media uses either analog (red) or digital (blue) signal pr ...
, analog broadcasts were largely phased out. Most US NTSC broadcasters were required by the FCC to shut down their analog transmitters by February 17th 2009, however this was later moved to June 12th 2009. Low-power stations, Class A stations and
translators Translation is the communication of the Meaning (linguistic), meaning of a translation#source and target languages, source-language text by means of an Dynamic and formal equivalence, equivalent translation#source and target languages, targe ...
were required to shut down by 2015, although an FCC extension allowed some of those stations operating on Channel 6 to operate until July 13, 2021. The remaining Canadian analog TV transmitters, in markets not subject to the mandatory transition in 2011, are scheduled to be shut down by January 14, 2022, under a schedule published by
Innovation, Science and Economic Development Canada Innovation, Science and Economic Development Canada (ISED; legally, the Department of Industry; french: Innovation, Sciences et Développement économique Canada), is the department of the Government of Canada The Government of Canada (french: g ...
in 2017; however the scheduled transition dates have already passed for several stations listed that continue to broadcast in analog (e.g.
CFJC-TV CFJC-TV, VHF analogue channel 4, is a Citytv- affiliated television station A television station is a set of equipment managed by a business, organisation or other entity, such as an amateur television (ATV) operator, that transmits video ...
Kamloops, which has not yet transitioned to digital, is listed as having been required to transition by November 20, 2020).


Technical details


Resolution and refresh rate

NTSC color encoding is used with the
System M , are in green. Comité consultatif international pour la radio, CCIR (or FCC The Federal Communications Commission (FCC) is an independent agency of the United States government that regulates communications by radio, television, wire, satell ...
television signal, which consists of  (approximately 29.97)  interlaced frames of
video Video is an electronic Electronic may refer to: *Electronics Electronics comprises the physics, engineering, technology and applications that deal with the emission, flow and control of electrons in vacuum and matter. It uses active d ...

video
per
second The second (symbol: s, also abbreviated: sec) is the base unit of time Time is the continued sequence of existence and event (philosophy), events that occurs in an apparently irreversible process, irreversible succession from the past, th ...
. Each frame is composed of two fields, each consisting of 262.5 scan lines, for a total of 525 scan lines. 486 scan lines make up the visible
raster Raster may refer to: * Raster graphics, graphical techniques using arrays of pixel values * Raster graphics editor, a computer program * Raster scan, the pattern of image readout, transmission, storage, and reconstruction in television and computer ...
. The remainder (the
vertical blanking interval In a raster scan A raster scan, or raster scanning, is the rectangular pattern of image capture and reconstruction in television. By analogy, the term is used for raster graphics file:Rgb-raster-image.svg, upright=1, The Smiley, smiley face ...
) allow for vertical
synchronization Synchronization is the coordination of events to operate a system A system is a group of Interaction, interacting or interrelated elements that act according to a set of rules to form a unified whole. A system, surrounded and influenced by ...

synchronization
and retrace. This blanking interval was originally designed to simply blank the electron beam of the receiver's CRT to allow for the simple analog circuits and slow vertical retrace of early TV receivers. However, some of these lines may now contain other data such as
closed captioning Closed captioning (CC) and are both processes of displaying on a , , or other visual display to provide additional or interpretive information. Both are typically used as a of the portion of a as it occurs (either or in edited form), some ...
and vertical interval
timecode A timecode (alternatively, time code) is a sequence of numeric codes generated at regular intervals by a timing synchronization system. Timecode is used in video production, show control and other applications which require temporal coordination ...
(VITC). In the complete
raster Raster may refer to: * Raster graphics, graphical techniques using arrays of pixel values * Raster graphics editor, a computer program * Raster scan, the pattern of image readout, transmission, storage, and reconstruction in television and computer ...
(disregarding half lines due to interlacing) the even-numbered scan lines (every other line that would be even if counted in the video signal, e.g. ) are drawn in the first field, and the odd-numbered (every other line that would be odd if counted in the video signal, e.g. ) are drawn in the second field, to yield a flicker-free image at the field refresh
frequency Frequency is the number of occurrences of a repeating event per unit of time A unit of time is any particular time Time is the indefinite continued sequence, progress of existence and event (philosophy), events that occur in an apparen ...

frequency
of  Hz (approximately 59.94 Hz). For comparison, 576i systems such as PAL-B/G and
SECAM 300px, upright=1.2, Analog television encoding systems by nation; NTSC (green), SECAM (orange), and PAL (blue).">PAL.html" ;"title="NTSC (green), SECAM (orange), and PAL">NTSC (green), SECAM (orange), and PAL (blue). SECAM, also written SÉ ...

SECAM
use 625 lines (576 visible), and so have a higher vertical resolution, but a lower temporal resolution of 25 frames or 50 fields per second. The NTSC field refresh frequency in the black-and-white system originally exactly matched the nominal 60 Hz
frequency Frequency is the number of occurrences of a repeating event per unit of time A unit of time is any particular time Time is the indefinite continued sequence, progress of existence and event (philosophy), events that occur in an apparen ...
of
alternating current Alternating current (AC) is an electric current An electric current is a stream of charged particle In physics Physics (from grc, φυσική (ἐπιστήμη), physikḗ (epistḗmē), knowledge of nature, from ''phýsis'' 'natu ...
power used in the United States. Matching the field
refresh rate The refresh rate (or "vertical refresh rate", "vertical scan rate", terminology originating with the cathode ray tubes) is the number of times per second that a Raster scan, raster-based display device displays a new image. This is independent from ...
to the power source avoided
intermodulation plot showing intermodulation between two injected signals at 270 and 275 MHz (the large spikes). Visible intermodulation products are seen as small spurs at 280 MHz and 265 MHz. Intermodulation (IM) or intermodulation distortion (IMD) is the am ...
(also called ''beating''), which produces rolling bars on the screen. Synchronization of the refresh rate to the power incidentally helped
kinescope Kinescope , shortened to kine , also known as telerecording in Britain, is a recording of a television program on motion picture film Film stock is an analog medium that is used for recording motion pictures A film, also calle ...
cameras record early live television broadcasts, as it was very simple to synchronize a
film A film, also called a movie, motion picture or moving picture, is a work of visual art The visual arts are art forms such as painting Painting is the practice of applying paint Paint is any pigmented liquid, liquefiable, ...

film
camera to capture one frame of video on each film frame by using the alternating current frequency to set the speed of the synchronous AC motor-drive camera. When color was added to the system, the refresh frequency was shifted slightly downward by 0.1% to approximately 59.94 Hz to eliminate stationary dot patterns in the difference frequency between the sound and color carriers, as explained below in " Color encoding". By the time the frame rate changed to accommodate color, it was nearly as easy to trigger the camera shutter from the video signal itself. The actual figure of 525 lines was chosen as a consequence of the limitations of the vacuum-tube-based technologies of the day. In early TV systems, a master
voltage-controlled oscillator A microwave (12–18GHz) voltage-controlled oscillator A voltage-controlled oscillator (VCO) is an electronic oscillator An electronic oscillator is an electronic circuit 200px, A circuit built on a printed circuit board (PCB). An electroni ...

voltage-controlled oscillator
was run at twice the horizontal line frequency, and this frequency was divided down by the number of lines used (in this case 525) to give the field frequency (60 Hz in this case). This frequency was then compared with the 60 Hz power-line frequency and any discrepancy corrected by adjusting the frequency of the master oscillator. For interlaced scanning, an odd number of lines per frame was required in order to make the vertical retrace distance identical for the odd and even fields, which meant the master oscillator frequency had to be divided down by an odd number. At the time, the only practical method of frequency division was the use of a chain of
vacuum tube A vacuum tube, electron tube, valve (British usage), or tube (North America), is a device that controls electric current flow in a high vacuum between electrodes to which an electric voltage, potential difference has been applied. The type kn ...
multivibrator A multivibrator is an used to implement a variety of simple two-state devices such as s, s, and . It consists of two (s, s, or other devices) cross-coupled by s or s. The first multivibrator circuit, the astable multivibrator , was invented by ...

multivibrator
s, the overall division ratio being the mathematical product of the division ratios of the chain. Since all the factors of an odd number also have to be odd numbers, it follows that all the dividers in the chain also had to divide by odd numbers, and these had to be relatively small due to the problems of thermal drift with vacuum tube devices. The closest practical sequence to 500 that meets these criteria was . (For the same reason, 625-line PAL-B/G and SECAM uses , the old British 405-line system used , the French 819-line system used etc.)


Colorimetry

The original 1953 color NTSC specification, still part of the United States
Code of Federal Regulations The ''Code of Federal Regulations'' (''CFR'') is the codification of the general and permanent regulations published in the ''Federal Register The ''Federal Register'' (FR or sometimes Fed. Reg.) is the official journal A government gazett ...

Code of Federal Regulations
, defined the
colorimetric Colorimetry is "the science and technology used to quantify and describe physically the human color perception". It is similar to spectrophotometry Spectrophotometry is a branch of electromagnetic spectroscopy concerned with the quantit ...
values of the system as follows: Early color television receivers, such as the RCA
CT-100 The RCA CT-100 was an early all-electronic consumer color television introduced in April 1954. The color picture tube measured 15 inches diagonally. The viewable picture was just 11½ inches wide. The CT-100 wasn't the world's first color T ...
, were faithful to this specification (which was based on prevailing motion picture standards), having a larger gamut than most of today's monitors. Their low-efficiency phosphors (notably in the Red) were weak and long-persistent, leaving trails after moving objects. Starting in the late 1950s, picture tube phosphors would sacrifice saturation for increased brightness; this deviation from the standard at both the receiver and broadcaster was the source of considerable color variation.


SMPTE C

To ensure more uniform color reproduction, receivers started to incorporate color correction circuits that converted the received signal—encoded for the colorimetric values listed above—into signals encoded for the phosphors actually used within the monitor. Since such color correction can not be performed accurately on the nonlinear gamma corrected signals transmitted, the adjustment can only be approximated, introducing both hue and
luminance Luminance is a photometricPhotometry can refer to: * Photometry (optics), the science of measurement of visible light in terms of its perceived brightness to human vision * Photometry (astronomy), the measurement of the flux or intensity of an ...
errors for highly saturated colors. Similarly at the broadcaster stage, in 1968–69 the Conrac Corp., working with RCA, defined a set of controlled phosphors for use in broadcast color picture
video monitor A display device is an output device An output device is any piece of computer hardware Computer hardware includes the physical parts of a computer A computer is a machine that can be programmed to carry out sequences of arithmetic or ...
s.DeMarsh, Leroy (1993): TV Display Phosphors/Primaries — Some History. SMPTE Journal, December 1993: 1095–1098. This specification survives today as the SMPTE "C" phosphor specification: As with home receivers, it was further recommendedInternational Telecommunications Union Recommendation ITU-R 470-6 (1970–1998): Conventional Television Systems, Annex 2. that studio monitors incorporate similar color correction circuits so that broadcasters would transmit pictures encoded for the original 1953 colorimetric values, in accordance with FCC standards. In 1987, the
Society of Motion Picture and Television Engineers The Society of Motion Picture and Television Engineers (SMPTE) (, rarely ), founded in 1916 as the Society of Motion Picture Engineers or SMPE, is a global professional association of engineers, technologists, and executives working in the ...
(SMPTE) Committee on Television Technology, Working Group on Studio Monitor Colorimetry, adopted the SMPTE C (Conrac) phosphors for general use in Recommended Practice 145,Society of Motion Picture and Television Engineers (1987–2004): Recommended Practice RP 145-2004. Color Monitor Colorimetry. prompting many manufacturers to modify their camera designs to directly encode for SMPTE "C" colorimetry without color correction,Society of Motion Picture and Television Engineers (1994, 2004): Engineering Guideline EG 27-2004. Supplemental Information for SMPTE 170M and Background on the Development of NTSC Color Standards, pp. 9 as approved in SMPTE standard 170M, "Composite Analog Video Signal – NTSC for Studio Applications" (1994). As a consequence, the
ATSC Advanced Television Systems Committee (ATSC) standards are an American set of standards for digital television transmission over terrestrial, cable and satellite networks. It is largely a replacement for the analog NTSC standard and, like that ...
digital television standard states that for
480i 480i is the video Video is an electronic Electronic may refer to: *Electronics Electronics comprises the physics, engineering, technology and applications that deal with the emission, flow and control of electrons in vacuum and matt ...
signals, SMPTE "C" colorimetry should be assumed unless colorimetric data is included in the transport stream. Japanese NTSC never changed primaries and whitepoint to SMPTE "C", continuing to use the 1953 NTSC primaries and whitepoint. Both the
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and
SECAM 300px, upright=1.2, Analog television encoding systems by nation; NTSC (green), SECAM (orange), and PAL (blue).">PAL.html" ;"title="NTSC (green), SECAM (orange), and PAL">NTSC (green), SECAM (orange), and PAL (blue). SECAM, also written SÉ ...

SECAM
systems used the original 1953 NTSC colorimetry as well until 1970; unlike NTSC, however, the European Broadcasting Union (EBU) rejected color correction in receivers and studio monitors that year and instead explicitly called for all equipment to directly encode signals for the "EBU" colorimetric values,European Broadcasting Union (1975) Tech. 3213-E.: E.B.U. Standard for Chromaticity Tolerances for Studio Monitors. further improving the color fidelity of those systems.


Color encoding

For backward compatibility with black-and-white television, NTSC uses a
luminance Luminance is a photometricPhotometry can refer to: * Photometry (optics), the science of measurement of visible light in terms of its perceived brightness to human vision * Photometry (astronomy), the measurement of the flux or intensity of an ...
-
chrominance Chrominance (''chroma'' or ''C'' for short) is the signal used in video systems to convey the color information of the picture, separately from the accompanying Luma (video), luma signal (or Y' for short). Chrominance is usually represented as two ...
encoding system invented in 1938 by
Georges ValensiM. Georges Valensi (1889–1980) was a French telecommunications engineer who, in 1938, invented and patent NPOV disputes from March 2021 A patent is a Title (property), title that gives its owner the legal right to exclude others from making, ...
. The ''three'' color picture signals are divided into Luminance (derived mathematically from the three separate color signals (Red, Green and Blue)) which takes the place of the original monochrome signal and Chrominance which carries ''only'' the color information. This process is applied to ''each'' color source by its own Colorplexer, thereby allowing a compatible color source to be managed as if it were an ordinary monochrome source. This allows black-and-white receivers to display NTSC color signals by simply ignoring the chrominance signal. Some black-and-white TVs sold in the U.S. after the introduction of color broadcasting in 1953 were designed to filter chroma out, but the early B&W sets did not do this and chroma dots, chrominance could be seen as a 'dot pattern' in highly colored areas of the picture. In NTSC, chrominance is encoded using two color signals known as I (in-phase) and Q (in quadrature) in a process called Quadrature amplitude modulation, QAM. The two signals each amplitude modulate 3.58 MHz carriers which are 90 degrees out of phase with each other and the result added together but with the Double-sideband suppressed-carrier transmission, carriers themselves being suppressed. The result can be viewed as a single sine wave with varying phase relative to a reference carrier and with varying amplitude. The varying phase represents the instantaneous ''color hue'' captured by a TV camera, and the amplitude represents the instantaneous ''color saturation''. This 3.58 MHz
subcarrier A subcarrier is a sideband , fm is the maximum modulation frequency In radio Radio is the technology of signaling and telecommunication, communicating using radio waves. Radio waves are electromagnetic waves of frequency between 30 her ...
is then added to the Luminance to form the 'composite color signal' which modulates the video signal carrier signal, carrier just as in monochrome transmission. For a color TV to recover hue information from the color subcarrier, it must have a zero phase reference to replace the previously suppressed carrier. The NTSC signal includes a short sample of this reference signal, known as the colorburst, located on the 'back porch' of each horizontal synchronization pulse. The color burst consists of a minimum of eight cycles of the unmodulated (fixed phase and amplitude) color subcarrier. The TV receiver has a "local oscillator", which is synchronized with these color bursts. Combining this reference phase signal derived from the color burst with the chrominance signal's amplitude and phase allows the recovery of the 'I' and 'Q' signals which when combined with the Luminance information allows the reconstruction of a color image on the screen. Color TV has been said to really be color''ed'' TV because of the total separation of the brightness part of the picture from the color portion. In CRT televisions, the NTSC signal is turned into three color signals called Red, Green and Blue, each controlling that color electron gun. TV sets with digital circuitry use sampling techniques to process the signals but the end result is the same. For both analog and digital sets processing an analog NTSC signal, the original three color signals (Red, Green and Blue) are transmitted using three discrete signals (Luminance, I and Q) and then recovered as three separate colors and combined as a color image. When a transmitter broadcasts an NTSC signal, it amplitude-modulates a radio-frequency carrier with the NTSC signal just described, while it frequency-modulates a carrier 4.5 MHz higher with the audio signal. If non-linear distortion happens to the broadcast signal, the 3.579545 MHz color carrier may Beat (acoustics), beat with the sound carrier to produce a dot pattern on the screen. To make the resulting pattern less noticeable, designers adjusted the original 15,750 Hz scanline rate down by a factor of 1.001 (0.1%) to match the audio carrier frequency divided by the factor 286, resulting in a field rate of approximately 59.94 Hz. This adjustment ensures that the difference between the sound carrier and the color subcarrier (the most problematic
intermodulation plot showing intermodulation between two injected signals at 270 and 275 MHz (the large spikes). Visible intermodulation products are seen as small spurs at 280 MHz and 265 MHz. Intermodulation (IM) or intermodulation distortion (IMD) is the am ...
product of the two carriers) is an odd multiple of half the line rate, which is the necessary condition for the dots on successive lines to be opposite in phase, making them least noticeable. The 59.94 rate is derived from the following calculations. Designers chose to make the chrominance subcarrier frequency an ''n'' + 0.5 multiple of the line frequency to minimize interference between the luminance signal and the chrominance signal. (Another way this is often stated is that the color subcarrier frequency is an odd multiple of half the line frequency.) They then chose to make the audio subcarrier frequency an integer multiple of the line frequency to minimize visible (intermodulation) interference between the audio signal and the chrominance signal. The original black-and-white standard, with its 15,750 Hz line frequency and 4.5 MHz audio subcarrier, does not meet these requirements, so designers had either to raise the audio subcarrier frequency or lower the line frequency. Raising the audio subcarrier frequency would prevent existing (black and white) receivers from properly tuning in the audio signal. Lowering the line frequency is comparatively innocuous, because the horizontal and vertical synchronization information in the NTSC signal allows a receiver to tolerate a substantial amount of variation in the line frequency. So the engineers chose the line frequency to be changed for the color standard. In the black-and-white standard, the ratio of audio subcarrier frequency to line frequency is   285.71. In the color standard, this becomes rounded to the integer 286, which means the color standard's line rate is  ≈ 15,734 Hz. Maintaining the same number of scan lines per field (and frame), the lower line rate must yield a lower field rate. Dividing lines per second by 262.5 lines per field gives approximately 59.94 fields per second.


Transmission modulation method

An NTSC television channel as transmitted occupies a total bandwidth of 6 MHz. The actual video signal, which is amplitude modulation, amplitude-modulated, is transmitted between 500 Hertz, kHz and 5.45 MHz above the lower bound of the channel. The video carrier signal, carrier is 1.25 MHz above the lower bound of the channel. Like most AM signals, the video carrier generates two sidebands, one above the carrier and one below. The sidebands are each 4.2 MHz wide. The entire upper sideband is transmitted, but only 1.25 MHz of the lower sideband, known as a vestigial sideband, is transmitted. The color subcarrier, as noted above, is 3.579545 MHz above the video carrier, and is quadrature amplitude modulation, quadrature-amplitude-modulated with a suppressed carrier. The audio signal is frequency modulation, frequency-modulated, like the audio signals broadcast by FM broadcasting, FM radio Radio broadcasting, stations in the 88–108 MHz band, but with a 25 kHz maximum frequency deviation, as opposed to 75 kHz as is used on the FM broadcast band, FM band, making analog television audio signals sound quieter than FM radio signals as received on a wideband receiver. The main audio carrier is 4.5 MHz above the video carrier, making it 250 kHz below the top of the channel. Sometimes a channel may contain an Multichannel television sound, MTS signal, which offers more than one audio signal by adding one or two subcarriers on the audio signal, each synchronized to a multiple of the line frequency. This is normally the case when stereophonic sound, stereo audio and/or second audio program signals are used. The same extensions are used in
ATSC Advanced Television Systems Committee (ATSC) standards are an American set of standards for digital television transmission over terrestrial, cable and satellite networks. It is largely a replacement for the analog NTSC standard and, like that ...
, where the ATSC digital carrier is broadcast at 0.31 MHz above the lower bound of the channel. "Setup" is a 54 mV (7.5 IRE (unit), IRE) voltage offset between the "black" and "blanking" levels. It is unique to NTSC. CVBS stands for Color, Video, Blanking, and Sync. The following table shows the values for the basic RGB colors, encoded in NTSC


Frame rate conversion

There is a large difference in
frame rate Frame rate (expressed in or FPS) is the frequency Frequency is the number of occurrences of a repeating event per unit of time A unit of time is any particular time Time is the indefinite continued sequence, progress of existence an ...
between film, which runs at 24.0 frames per second, and the NTSC standard, which runs at approximately 29.97 (10 MHz×63/88/455/525) frames per second. In regions that use 25-fps television and video standards, this difference can be overcome by PAL speedup, speed-up. For 30-fps standards, a process called "Three-two pull down, 3:2 pulldown" is used. One film frame is transmitted for three video fields (lasting  video frames), and the next frame is transmitted for two video fields (lasting 1 video frame). Two film frames are thus transmitted in five video fields, for an average of  video fields per film frame. The average frame rate is thus 60 ÷ 2.5 = 24 frames per second, so the average film speed is nominally exactly what it should be. (In reality, over the course of an hour of real time, 215,827.2 video fields are displayed, representing 86,330.88 frames of film, while in an hour of true 24-fps film projection, exactly 86,400 frames are shown: thus, 29.97-fps NTSC transmission of 24-fps film runs at 99.92% of the film's normal speed.) Still-framing on playback can display a video frame with fields from two different film frames, so any difference between the frames will appear as a rapid back-and-forth flicker. There can also be noticeable jitter/"stutter" during slow camera pans (telecine judder). To avoid 3:2 pulldown, film shot specifically for NTSC television is often taken at 30 frame/s. To show 25-fps material (such as European television series and some European movies) on NTSC equipment, every fifth frame is duplicated and then the resulting stream is interlaced. Film shot for NTSC television at 24 frames per second has traditionally been accelerated by 1/24 (to about 104.17% of normal speed) for transmission in regions that use 25-fps television standards. This increase in picture speed has traditionally been accompanied by a similar increase in the pitch and tempo of the audio. More recently, frame-blending has been used to convert 24 FPS video to 25 FPS without altering its speed. Film shot for television in regions that use 25-fps television standards can be handled in either of two ways: * The film can be shot at 24 frames per second. In this case, when transmitted in its native region, the film may be accelerated to 25 fps according to the analog technique described above, or kept at 24 fps by the digital technique described above. When the same film is transmitted in regions that use a nominal 30-fps television standard, there is no noticeable change in speed, tempo, and pitch. * The film can be shot at 25 frames per second. In this case, when transmitted in its native region, the film is shown at its normal speed, with no alteration of the accompanying soundtrack. When the same film is shown in regions that use a 30-fps nominal television standard, every fifth frame is duplicated, and there is still no noticeable change in speed, tempo, and pitch. Because both film speeds have been used in 25-fps regions, viewers can face confusion about the true speed of video and audio, and the pitch of voices, sound effects, and musical performances, in television films from those regions. For example, they may wonder whether the Jeremy Brett series of Sherlock Holmes television films, made in the 1980s and early 1990s, was shot at 24 fps and then transmitted at an artificially fast speed in 25-fps regions, or whether it was shot at 25 fps natively and then slowed to 24 fps for NTSC exhibition. These discrepancies exist not only in television broadcasts over the air and through cable, but also in the home-video market, on both tape and disc, including laser disc and DVD. In digital television and video, which are replacing their analog predecessors, single standards that can accommodate a wider range of frame rates still show the limits of analog regional standards. The initial version of the
ATSC Advanced Television Systems Committee (ATSC) standards are an American set of standards for digital television Digital television (DTV) is the transmission of television audiovisual Audiovisual (AV) is electronic media possessing both a so ...

ATSC
standard, for example, allowed frame rates of 23.976, 24, 29.97, 30, 59.94, 60, 119.88 and 120 frames per second, but not 25 and 50. Modern ATSC allows 25 and 50 FPS.


Modulation for analog satellite transmission

Because satellite power is severely limited, analog video transmission through satellites differs from terrestrial TV transmission. Amplitude modulation, AM is a linear modulation method, so a given demodulated signal-to-noise ratio (SNR) requires an equally high received RF SNR. The SNR of studio quality video is over 50 dB, so AM would require prohibitively high powers and/or large antennas. Wideband Frequency modulation, FM is used instead to trade RF bandwidth for reduced power. Increasing the channel bandwidth from 6 to 36 MHz allows a RF SNR of only 10 dB or less. The wider noise bandwidth reduces this 40 dB power saving by 36 MHz / 6 MHz = 8 dB for a substantial net reduction of 32 dB. Sound is on an FM subcarrier as in terrestrial transmission, but frequencies above 4.5 MHz are used to reduce aural/visual interference. 6.8, 5.8 and 6.2 MHz are commonly used. Stereo can be multiplex, discrete, or matrix and unrelated audio and data signals may be placed on additional subcarriers. A triangular 60 Hz energy dispersal waveform is added to the composite baseband signal (video plus audio and data subcarriers) before modulation. This limits the satellite downlink Spectral density, power spectral density in case the video signal is lost. Otherwise the satellite might transmit all of its power on a single frequency, interfering with terrestrial microwave links in the same frequency band. In half transponder mode, the frequency deviation of the composite baseband signal is reduced to 18 MHz to allow another signal in the other half of the 36 MHz transponder. This reduces the FM benefit somewhat, and the recovered SNRs are further reduced because the combined signal power must be "backed off" to avoid intermodulation distortion in the satellite transponder. A single FM signal is constant amplitude, so it can saturate a transponder without distortion.


Field order

An NTSC "frame" consists of an "even" field followed by an "odd" field. As far as the reception of an analog signal is concerned, this is purely a matter of convention and, it makes no difference. It is rather like the broken lines running down the middle of a road, it does not matter whether it is a line/space pair or a space/line pair; the effect to a driver is exactly the same. The introduction of digital television formats has changed things somewhat. Most digital TV formats store and transmit fields in pairs as a single digital frame. Digital formats that match NTSC field rate, including the popular DVD format, record video with the ''even field first'' in the digital frame, while the formats that match field rate of the 625 line system often record video with ''odd frame first''. This means that when reproducing many non-NTSC based digital formats it is necessary to reverse the field order, otherwise an unacceptable shuddering "comb" effect occurs on moving objects as they are shown ahead in one field and then jump back in the next. This has also become a hazard where non NTSC progressive video is transcoded to interlaced and vice versa. Systems that recover progressive frames or transcode video should ensure that the "Field Order" is obeyed, otherwise the recovered frame will consist of a field from one frame and a field from an adjacent frame, resulting in "comb" interlacing artifacts. This can often be observed in PC based video playing utilities if an inappropriate choice of de-interlacing algorithm is made. During the decades of high-power NTSC broadcasts in the United States, switching between the views from two cameras was accomplished according to two Field dominance standards, the choice between the two being made by geography, East versus West. In one region, the switch was made between the odd field that finished one frame and the even field that began the next frame; in the other, the switch was made after an even field and before an odd field. Thus, for example, a home VHS recording made of a local television newscast in the East, when paused, would only ever show the view from one camera (unless a dissolve or other multicamera shot were intended), whereas VHS playback of a situation comedy taped and edited in Los Angeles and then transmitted nationwide could be paused at the moment of a switch between cameras with half the lines depicting the outgoing shot and the other half depicting the incoming shot.


Variants


NTSC-M

Unlike PAL and SECAM, with its many varied underlying
broadcast television systems Broadcast programming, Broadcast television systems (or terrestrial television systems outside the US and Canada) are the encoding or formatting standards for the transmission and reception of terrestrial television signals. There were three main ...
in use throughout the world, NTSC color encoding is almost invariably used with CCIR System M, broadcast system M, giving NTSC-M.


NTSC-N/NTSC50

NTSC-N/NTSC50 is an unofficial system combining 625-line video with 3.58 MHz NTSC color. PAL software running on an NTSC Atari ST displays using this system as it cannot display PAL color. Television sets and monitors with a V-Hold knob can display this system after adjusting the vertical hold.


NTSC-J

Only
Japan Japan ( ja, 日本, or , and formally ) is an island country An island country or an island nation is a country A country is a distinct territory, territorial body or political entity. It is often referred to as the land of an in ...

Japan
's variant "NTSC-J" is slightly different: in Japan, black level and blanking level of the signal are identical (at 0 IRE (unit), IRE), as they are in PAL, while in American NTSC, black level is slightly higher (7.5 IRE (unit), IRE) than blanking level. Since the difference is quite small, a slight turn of the brightness knob is all that is required to correctly show the "other" variant of NTSC on any set as it is supposed to be; most watchers might not even notice the difference in the first place. The channel encoding on NTSC-J differs slightly from NTSC-M. In particular, the Japanese VHF band runs from channels 1–12 (located on frequencies directly above the 76–90 MHz Japanese FM broadcasting, FM radio band) while the North American VHF TV band uses channels 2–13 (54–72 MHz, 76–88 MHz and 174–216 MHz) with 88–108 MHz allocated to FM radio broadcasting. Japan's UHF TV channels are therefore numbered from 13 up and not 14 up, but otherwise uses the same UHF broadcasting frequencies as those in North American television frequencies, North America.


PAL-M (Brazil)

The Brazilian PAL-M system, introduced on February 19, 1972, uses the same lines/field as NTSC (525/60), and almost the same broadcast bandwidth and scan frequency (15.750 vs. 15.734 kHz). Prior to the introduction of color, Brazil broadcast in standard black-and-white NTSC. As a result, PAL-M signals are near identical to North American NTSC signals, except for the encoding of the color subcarrier (3.575611 MHz for PAL-M and 3.579545 MHz for NTSC). As a consequence of these close specs, PAL-M will display in monochrome with sound on NTSC sets and vice versa.


PAL-N

This is used in Argentina, Paraguay and Uruguay. This is very similar to PAL-M (used in Brazil). The similarities of NTSC-M and NTSC-N can be seen on the ITU analog television standards, ITU identification scheme table, which is reproduced here: As it is shown, aside from the number of lines and frame rate, frames per second, the systems are identical. NTSC-N/PAL-N are compatible with sources such as Video game console, game consoles, VHS/Betamax VCRs, and DVD players. However, they are not compatible with baseband broadcasts (which are received over an Antenna (radio), antenna), though some newer sets come with baseband NTSC 3.58 support (NTSC 3.58 being the frequency for color modulation in NTSC: 3.58 MHz).


NTSC 4.43

In what can be considered an opposite of PAL, PAL-60, NTSC 4.43 is a pseudo-color system that transmits NTSC encoding (525/29.97) with a color subcarrier of 4.43 MHz instead of 3.58 MHz. The resulting output is only viewable by TVs that support the resulting pseudo-system (such as most PAL TVs since around the mid-1990s). Using a native NTSC TV to decode the signal yields no color, while using an incompatible PAL TV to decode the system yields erratic colors (observed to be lacking red and flickering randomly). The format was used by the United States Air Force, USAF TV based in Germany during the Cold War. It was also found as an optional output on some LaserDisc players and some game consoles sold in markets where the PAL system is used. The NTSC 4.43 system, while not a broadcast format, appears most often as a playback function of PAL cassette format VCRs, beginning with the Sony 3/4" U-Matic format and then following onto Betamax and VHS format machines. As Hollywood has the claim of providing the most cassette software (movies and television series) for VCRs for the world's viewers, and as not ''all'' cassette releases were made available in PAL formats, a means of playing NTSC format cassettes was highly desired. Multi-standard video monitors were already in use in Europe to accommodate broadcast sources in PAL, SECAM, and NTSC video formats. The Heterodyne#Heterodyning in analog videotape recording, heterodyne color-under process of U-Matic, Betamax & VHS lent itself to minor modification of VCR players to accommodate NTSC format cassettes. The color-under format of VHS uses a 629 kHz subcarrier while U-Matic & Betamax use a 688 kHz subcarrier to carry an ''amplitude modulated'' chroma signal for both NTSC and PAL formats. Since the VCR was ready to play the color portion of the NTSC recording using PAL color mode, the PAL scanner and capstan speeds had to be adjusted from PAL's 50 Hz field rate to NTSC's 59.94 Hz field rate, and faster linear tape speed. The changes to the PAL VCR are minor thanks to the existing VCR recording formats. The output of the VCR when playing an NTSC cassette in NTSC 4.43 mode is 525 lines/29.97 frames per second with PAL compatible heterodyned color. The multi-standard receiver is already set to support the NTSC H & V frequencies; it just needs to do so while receiving PAL color. The existence of those multi-standard receivers was probably part of the drive for region coding of DVDs. As the color signals are component on disc for all display formats, almost no changes would be required for PAL DVD players to play NTSC (525/29.97) discs as long as the display was frame-rate compatible.


OSKM

In January 1960 (7 years prior to adoption of the modified SECAM version) the experimental TV studio in Moscow started broadcasting using the OSKM system. The OSKM abbreviation means "Simultaneous system with quadrature modulation" (In Russian: Одновременная Система с Квадратурной Модуляцией). It used the color coding scheme that was later used in PAL (U and V instead of I and Q), because it was based on D/K monochrome standard, 625/50. The color subcarrier frequency was 4.4296875 MHz and the bandwidth of U and V signals was near 1.5 MHz. Only circa 4000 TV sets of 4 models (Raduga, Temp-22, Izumrud-201 and Izumrud-203) were produced for studying the real quality of TV reception. These TV's were not commercially available, despite being included in the goods catalog for trade network of the USSR. The broadcasting with this system lasted about 3 years and was ceased well before SECAM transmissions started in the USSR. None of the current multi-standard TV receivers can support this TV system.


NTSC-film

Film content commonly shot at 24 frames/s can be converted to 30 frames/s through the telecine process to duplicate frames as needed. : \frac = \frac Mathematically for NTSC this is relatively simple as it is only needed to duplicate every fourth frame. Various techniques are employed. NTSC with an actual frame rate of   (approximately 23.976) frames/s is often defined as NTSC-film. A process known as pullup, also known as pulldown, generates the duplicated frames upon playback. This method is common for H.262/MPEG-2 Part 2 digital video so the original content is preserved and played back on equipment that can display it or can be converted for equipment that cannot.


Canada/US video game region

Sometimes ''NTSC-U'', ''NTSC-US'', or ''NTSC-U/C'' is used to describe the video gaming region of North America (the U/C refers to US + Canada), as regional lockout usually restricts games from being playable outside the region.


Comparative quality

For NTSC, and to a lesser extent, PAL, reception problems can degrade the color accuracy of the picture where ghosting can dynamically change the phase of the color burst with picture content, thus altering the color balance of the signal. The only receiver compensation is in the professional TV receiver ghost cancelling circuits used by cable companies. The vacuum-tube electronics used in televisions through the 1960s led to various technical problems. Among other things, the color burst phase would often drift. In addition, the TV studios did not always transmit properly, leading to hue changes when channels were changed, which is why NTSC televisions were equipped with a tint control. PAL and SECAM televisions had less of a need for one. SECAM in particular was very robust, but PAL, while excellent in maintaining skin tones which viewers are particularly sensitive to, never-the-less would distort other colors in the face of phase errors. With phase errors, only "Deluxe PAL" receivers would get rid of "Hanover bars" distortion. Hue controls are still found on NTSC TVs, but color drifting generally ceased to be a problem for more modern circuitry by the 1970s. When compared to PAL in particular, NTSC color accuracy and consistency was sometimes considered inferior, leading to video professionals and television engineers jokingly referring to NTSC as ''Never The Same Color'', ''Never Twice the Same Color'', or ''No True Skin Colors'', while for the more expensive PAL system it was necessary to ''Pay for Additional Luxury''. PAL has also been referred to as ''Peace At Last'', ''Perfection At Last'' or ''Pictures Always Lovely'' in the color war. This mostly applied to vacuum tube-based TVs, however, and later-model solid state sets using Vertical Interval Reference signals have less of a difference in quality between NTSC and PAL. This color phase, "tint", or "hue" control allows for anyone skilled in the art to easily calibrate a monitor with SMPTE color bars, even with a set that has drifted in its color representation, allowing the proper colors to be displayed. Older PAL television sets did not come with a user accessible "hue" control (it was set at the factory), which contributed to its reputation for reproducible colors. The use of NTSC coded color in S-Video systems, as well as the use of closed-circuit composite NTSC, both eliminate the phase distortions because there is no reception ghosting in a closed-circuit system to smear the color burst. For VHS video tape on the horizontal axis and frame rate of the three color systems when used with this scheme, the use of S-Video gives the higher resolution picture quality on monitors and TVs without a high quality motion-compensated comb filtering section. (The NTSC resolution on the vertical axis is lower than the European standards, 525 lines against 625.) However, it uses too much bandwidth for over-the-air transmission. The Atari 800 and Commodore 64 home computers generated S-video, but only when used with specially designed monitors as no TV at the time supported the separate chroma and luma on standard RCA jacks. In 1987, a standardized four-pin mini-DIN socket was introduced for S-video input with the introduction of S-VHS players, which were the first device produced to use the four-pin plugs. However, S-VHS never became very popular. Video game consoles in the 1990s began offering S-video output as well. The mismatch between NTSC's 30 frames per second and film's 24 frames is overcome by a process that capitalizes on the ''field'' rate of the interlaced NTSC signal, thus avoiding the film playback speedup used for 576i systems at 25 frames per second (which causes the accompanying audio to increase in pitch slightly, sometimes rectified with the use of a pitch shifter) at the price of some Telecine judder, jerkiness in the video. See #Frame rate conversion, Frame rate conversion above.


Vertical interval reference

The standard NTSC video image contains some lines (lines 1–21 of each field) that are not visible (this is known as the Vertical Blanking Interval, or VBI); all are beyond the edge of the viewable image, but only lines 1–9 are used for the vertical-sync and equalizing pulses. The remaining lines were deliberately blanked in the original NTSC specification to provide time for the electron beam in CRT-based screens to return to the top of the display. VIR (or Vertical interval reference), widely adopted in the 1980s, attempts to correct some of the color problems with NTSC video by adding studio-inserted reference data for luminance and chrominance levels on line 19. Suitably equipped television sets could then employ these data in order to adjust the display to a closer match of the original studio image. The actual VIR signal contains three sections, the first having 70 percent luminance and the same chrominance as the Colorburst, color burst signal, and the other two having 50 percent and 7.5 percent luminance respectively. A less-used successor to VIR, ghost-canceling reference, GCR, also added ghost (multipath interference) removal capabilities. The remaining
vertical blanking interval In a raster scan A raster scan, or raster scanning, is the rectangular pattern of image capture and reconstruction in television. By analogy, the term is used for raster graphics file:Rgb-raster-image.svg, upright=1, The Smiley, smiley face ...
lines are typically used for datacasting or ancillary data such as video editing timestamps (vertical interval timecodes or Society of Motion Picture and Television Engineers, SMPTE timecodes on lines 12–14), Vertical Interval Test Signal, test data on lines 17–18, a network source code on line 20 and
closed captioning Closed captioning (CC) and are both processes of displaying on a , , or other visual display to provide additional or interpretive information. Both are typically used as a of the portion of a as it occurs (either or in edited form), some ...
, Extended Data Services, XDS, and V-chip data on EIA-608, line 21. Early teletext applications also used vertical blanking interval lines 14–18 and 20, but teletext over NTSC was never widely adopted by viewers. Many stations transmit TV Guide On Screen (Guide Plus, TVGOS) data for an electronic program guide on VBI lines. The primary station in a market will broadcast 4 lines of data, and backup stations will broadcast 1 line. In most markets the PBS station is the primary host. TVGOS data can occupy any line from 10–25, but in practice its limited to 11–18, 20 and line 22. Line 22 is only used for 2 broadcast, DirecTV and CFPL-DT, CFPL-TV. TiVo data is also transmitted on some commercials and program advertisements so that customers can autorecord the program being advertised, and is also used in weekly half-hour infomercial, paid programs on Ion Television and the Discovery Channel which highlight TiVo promotions and advertisers.


Countries and territories that are using or once used NTSC

Below countries and territories currently use or once used the NTSC system. Many of these have switched or are currently switching from NTSC to digital television standards such as
ATSC Advanced Television Systems Committee (ATSC) standards are an American set of standards for digital television transmission over terrestrial, cable and satellite networks. It is largely a replacement for the analog NTSC standard and, like that ...
(United States, Canada, Mexico, Suriname, South Korea),
ISDB Integrated Services Digital Broadcasting (ISDB; Japanese Japanese may refer to: * Something from or related to Japan , image_flag = Flag of Japan.svg , alt_flag = Centered deep red circle on a white ...
(Japan, Philippines and part of South America), DVB-T (Taiwan, Panama, Colombia and Trinidad and Tobago) or Digital Terrestrial Multimedia Broadcast, DTMB (Cuba). * * * * * * * * (Over-the-air NTSC broadcasts (Channel 9) have been terminated as of March 2016, local broadcast stations have now switched to digital channels 20.1 and 20.2.) * * * * (Over-the-air NTSC broadcasting in major cities ceased August 2011 as a result of legislative fiat, to be replaced with ATSC. Some one-station markets or markets served only by full-power repeaters remain analog.) * * * (Analog shutoff scheduled to 2022, simulcasting in ISDB-Tb.) * (NTSC broadcast to be abandoned by 2017, simulcasting DVB-T.) * (NTSC broadcast to be abandoned by December 2018, simulcasting ISDB-Tb.) * * * * (Over-the-air NTSC broadcasting scheduled to be abandoned by 2021, simulcast in ATSC.) * * (Over-the-air NTSC broadcasting scheduled to be abandoned by January 1, 2020, simulcast in ATSC.) * * * * * * * (Over-the-air NTSC broadcasting scheduled to be abandoned by December 2020, simulcast in ATSC.) * * (fully switched to
ISDB Integrated Services Digital Broadcasting (ISDB; Japanese Japanese may refer to: * Something from or related to Japan , image_flag = Flag of Japan.svg , alt_flag = Centered deep red circle on a white ...
in 2012, after the 2011 Tōhoku earthquake and tsunami delayed the planned 2011 rollout in three prefectures) * * (in Compact of Free Association with US; US aid funded NTSC adoption) * plans to transition from NTSC announced on July 2, 2004, started conversion in 2013 full transition was scheduled for December 31, 2015, but due to technical and economic issues for some transmitters, the full transition was extended to be completed on December 31, 2016. * (in Compact of Free Association with US, transitioning to DVB-T) * (a US military base) * * * * (in Compact of Free Association with US; adopted NTSC before independence) * (NTSC broadcasts to be abandoned by 2020, simulcasting DVB-T. NTSC broadcasts to be abandoned in areas with more than 90% of DVB-T reception.) * , (NTSC broadcast to be abandoned by December 31, 2017, simulcasting ISDB-Tb.) * (NTSC broadcast was intended to be abandoned at the end of 2015; however, in later 2014, it was postponed to 2019. All analog broadcast is expected to be shut off in 2023. It will simulcast in ISDB#ISDB-T, ISDB-T.) * * * * * * (used NTSC, SECAM and PAL, before switching to PAL in the early 1990s) * * * * * (Full-power over-the-air NTSC broadcasting was switched off on June 12, 2009 in favor of ATSC. Low-power stations, Class A stations were switched off on September 1, 2015. Broadcast relay station, Translators and other Low-power stations were supposed to transition on the same day Class-A stations shut off analog services but it was postponed to July 13, 2021, due to a spectrum auction. Most remaining analog cable television systems are also not affected.) * *


Experimented

* (Between 1962 and 1963, Rede Tupi and Rede Excelsior made the first unofficial transmissions in color, in specific programs in the city of São Paulo, before the official adoption of PAL-M by the Brazilian Government on February 19, 1972) * * (Experimented on 405-line variant of NTSC, then UK chose 625-line for PAL broadcasting.)


Countries and territories that have ceased using NTSC

The following countries and regions no longer use NTSC for terrestrial broadcasts.


See also

* Broadcast television systems ** Advanced Television Systems Committee standards ** Multichannel television sound, BTSC ** NTSC-J ** NTSC-C **
PAL 300px, upright=1.2, Analog television encoding systems by nation; SECAM.html"_;"title="NTSC_(green),_SECAM">NTSC_(green),_SECAM_(orange),_and_PAL_(blue). Phase_Alternating_Line_(PAL)_is_a_colour_encoding_system_for_Analog_television.html" ;"ti ...
**
RCA The RCA Corporation was a major American electronics company, which was founded as the Radio Corporation of America in 1919. It was initially a patent trust owned by General Electric General Electric Company (GE) is an American multinatio ...
**
SECAM 300px, upright=1.2, Analog television encoding systems by nation; NTSC (green), SECAM (orange), and PAL (blue).">PAL.html" ;"title="NTSC (green), SECAM (orange), and PAL">NTSC (green), SECAM (orange), and PAL (blue). SECAM, also written SÉ ...

SECAM
*Composite artifact colors *Dot crawl * List of common resolutions#Television, List of common resolutions – Television * List of video connectors * Moving image formats * Prewar television stations, Oldest television station * Television channel frequencies ** Very high frequency ** Ultra high frequency ** Knife-edge effect ** Channel 1 (North American TV) ** Channel 37 ** North American broadcast television frequencies ** North American cable television frequencies ** Australasian television frequencies, Australasian TV frequencies * Broadcast-safe * Digital television transition in the United States * Glossary of video terms


References


Sources

* A standard defining the NTSC system was published by the International Telecommunication Union in 1998 under the title "Recommendation ITU-R BT.470-7, Conventional Analog Television Systems". It is publicly available on the Internet a
ITU-R BT.470-7
or can be purchased from th
ITU
* Ed Reitan (1997)


External links


National Television System Committee




– at TVTower.com

* [https://web.archive.org/web/20140222023017/http://www.avsforum.com/t/223615/does-59-94-hz-60-hz "Why 59.94 vs 60 Hz"] {{Telecommunications History of television ITU-R recommendations Television terminology Television transmission standards Video formats Video signal