NTSC
Encyclopedia
Analog television
Analog television is the analog transmission that involves the broadcasting of encoded analog audio and analog video signal: one in which the message conveyed by the broadcast signal is a function of deliberate variations in the amplitude and/or frequency of the signal...
system that is used in most of North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
, most of South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
(except Brazil
Brazil
Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...
, Argentina
Argentina
Argentina , officially the Argentine Republic , is the second largest country in South America by land area, after Brazil. It is constituted as a federation of 23 provinces and an autonomous city, Buenos Aires...
, Uruguay
Uruguay
Uruguay ,officially the Oriental Republic of Uruguay,sometimes the Eastern Republic of Uruguay; ) is a country in the southeastern part of South America. It is home to some 3.5 million people, of whom 1.8 million live in the capital Montevideo and its metropolitan area...
, and French Guiana
French Guiana
French Guiana is an overseas region of France, consisting of a single overseas department located on the northern Atlantic coast of South America. It has borders with two nations, Brazil to the east and south, and Suriname to the west...
), Burma, South Korea
South Korea
The Republic of Korea , , is a sovereign state in East Asia, located on the southern portion of the Korean Peninsula. It is neighbored by the People's Republic of China to the west, Japan to the east, North Korea to the north, and the East China Sea and Republic of China to the south...
, Taiwan
Taiwan
Taiwan , also known, especially in the past, as Formosa , is the largest island of the same-named island group of East Asia in the western Pacific Ocean and located off the southeastern coast of mainland China. The island forms over 99% of the current territory of the Republic of China following...
, Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
, the Philippines
Philippines
The Philippines , officially known as the Republic of the Philippines , is a country in Southeast Asia in the western Pacific Ocean. To its north across the Luzon Strait lies Taiwan. West across the South China Sea sits Vietnam...
, and some Pacific island nations and territories (see map).
Most countries using the NTSC standard, as well as those using other analog television standards, are switching to newer digital television
Digital television
Digital television is the transmission of audio and video by digital signals, in contrast to the analog signals used by analog TV...
standards, of which at least four different ones are in use around the world. North America, parts of Central America
Central America
Central America is the central geographic region of the Americas. It is the southernmost, isthmian portion of the North American continent, which connects with South America on the southeast. When considered part of the unified continental model, it is considered a subcontinent...
, and South Korea
South Korea
The Republic of Korea , , is a sovereign state in East Asia, located on the southern portion of the Korean Peninsula. It is neighbored by the People's Republic of China to the west, Japan to the east, North Korea to the north, and the East China Sea and Republic of China to the south...
are adopting the ATSC standards, while other countries are adopting or have adopted other standards.
The first NTSC standard was developed in 1941 and had no provision for color television. In 1953 a second modified version of the NTSC standard was adopted, which allowed color television
Color television
Color television is part of the history of television, the technology of television and practices associated with television's transmission of moving images in color video....
broadcasting compatible with the existing stock of black-and-white receivers. NTSC was the first widely adopted broadcast color system. After nearly 70 years of use, the vast majority of over-the-air NTSC transmissions in the United States were replaced
DTV transition in the United States
The DTV transition in the United States was the switchover from analog to exclusively digital broadcasting of free over-the-air television programming...
with digital
Digital television
Digital television is the transmission of audio and video by digital signals, in contrast to the analog signals used by analog TV...
ATSC on June 12, 2009 and August 31, 2011 in Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
and most other NTSC markets. Despite the shift to digital broadcasting, standard definition television in these countries continues to follow the NTSC standard in terms of frame rate
Frame rate
Frame rate is the frequency at which an imaging device produces unique consecutive images called frames. The term applies equally well to computer graphics, video cameras, film cameras, and motion capture systems...
and number of lines of resolution. In the United States a small number of short-range local and TV relay stations continue to broadcast NTSC, as the FCC allows. NTSC baseband video signals are also still often used in video playback (typically of recordings from existing libraries using existing equipment) and in CCTV and surveillance video systems.
History
The National Television System Committee was established in 1940 by the United States Federal Communications CommissionFederal Communications Commission
The Federal Communications Commission is an independent agency of the United States government, created, Congressional statute , and with the majority of its commissioners appointed by the current President. The FCC works towards six goals in the areas of broadband, competition, the spectrum, the...
(FCC) to resolve the conflicts that arose 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
Black-and-white
Black-and-white, often abbreviated B/W or B&W, is a term referring to a number of monochrome forms in visual arts.Black-and-white as a description is also something of a misnomer, for in addition to black and white, most of these media included varying shades of gray...
television that built upon a 1936 recommendation made by the Radio Manufacturers Association (RMA). Technical advancements of the vestigial sideband technique allowed for the opportunity to increase the image resolution. The NTSC selected 525 scan lines as a compromise between RCA
RCA
RCA Corporation, founded as the Radio Corporation of America, was an American electronics company in existence from 1919 to 1986. The RCA trademark is currently owned by the French conglomerate Technicolor SA through RCA Trademark Management S.A., a company owned by Technicolor...
's 441-scan line
Scan line
A scan line or scanline is one line, or row, in a raster scanning pattern, such as a line of video on a cathode ray tube display of a television set or computer monitor....
standard (already being used by RCA's NBC
NBC
The National Broadcasting Company is an American commercial broadcasting television network and former radio network headquartered in the GE Building in New York City's Rockefeller Center with additional major offices near Los Angeles and in Chicago...
TV network) and Philco
Philco
Philco, the Philadelphia Storage Battery Company , was a pioneer in early battery, radio, and television production as well as former employer of Philo Farnsworth, inventor of cathode ray tube television...
's and DuMont
DuMont Television Network
The DuMont Television Network, also known as the DuMont Network, DuMont, Du Mont, or Dumont was one of the world's pioneer commercial television networks, rivalling NBC for the distinction of being first overall. It began operation in the United States in 1946. It was owned by DuMont...
's desire to increase the number of scan lines to between 605 and 800. The standard recommended a frame rate
Frame rate
Frame rate is the frequency at which an imaging device produces unique consecutive images called frames. The term applies equally well to computer graphics, video cameras, film cameras, and motion capture systems...
of 30 frames (images) per second, consisting of two interlaced fields
Field (video)
In video, a field is one of the many still images which are displayed sequentially to create the impression of motion on the screen. Two fields comprise one video frame...
per frame at 262.5 lines per field and 60 fields per second. Other standards in the final recommendation were an aspect ratio
Aspect ratio (image)
The aspect ratio of an image is the ratio of the width of the image to its height, expressed as two numbers separated by a colon. That is, for an x:y aspect ratio, no matter how big or small the image is, if the width is divided into x units of equal length and the height is measured using this...
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
Color television is part of the history of television, the technology of television and practices associated with television's transmission of moving images in color video....
. In December 1953, it 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 existing black-and-white television sets. Color information was added to the black-and-white image by adding a color subcarrier
Subcarrier
A subcarrier is a separate analog or digital signal carried on a main radio transmission, which carries extra information such as voice or data. More technically, it is an already-modulated signal, which is then modulated into another signal of higher frequency and bandwidth...
of 4.5 × 455/572 = 315/88 MHz (approximately 3.58 MHz) to the video signal. To reduce the visibility of interference between the chrominance
Chrominance
Chrominance is the signal used in video systems to convey the color information of the picture, separately from the accompanying luma signal . Chrominance is usually represented as two color-difference components: U = B' − Y' and V = R' − Y'...
signal and FM sound carrier required a slight reduction of the frame rate
Frame rate
Frame rate is the frequency at which an imaging device produces unique consecutive images called frames. The term applies equally well to computer graphics, video cameras, film cameras, and motion capture systems...
from 30 frames per second to 30/1.001 (approximately 29.97) frames per second, and changing the line frequency from 15,750 Hz to 15,750/1.001 Hz (approximately 15,734.26 Hz).
The FCC had briefly approved a different color television standard, starting in October 1950, which was developed by CBS
CBS
CBS Broadcasting Inc. is a major US commercial broadcasting television network, which started as a radio network. The name is derived from the initials of the network's former name, Columbia Broadcasting System. The network is sometimes referred to as the "Eye Network" in reference to the shape of...
. However, this standard was incompatible with black-and-white broadcasts. It used a rotating color wheel, reduced the number of scan line
Scan line
A scan line or scanline is one line, or row, in a raster scanning pattern, such as a line of video on a cathode ray tube display of a television set or computer monitor....
s from 525 to 405, and increased the field rate from 60 to 144, but had an effective frame rate
Frame rate
Frame rate is the frequency at which an imaging device produces unique consecutive images called frames. The term applies equally well to computer graphics, video cameras, film cameras, and motion capture systems...
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
Office of Defense Mobilization
The Office of Defense Mobilization was an independent agency of the United States government whose function was to plan, coordinate, direct and control all wartime mobilization activities of the federal government, including manpower, economic stabilization, and transport operations...
(ODM) in October, ostensibly due to the Korean War
Korean War
The Korean War was a conventional war between South Korea, supported by the United Nations, and North Korea, supported by the People's Republic of China , with military material aid from the Soviet Union...
. 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. 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
Kukla, Fran and Ollie is an early American television show using puppets, originally created for children but soon watched by more adults than children. It did not have a script and was entirely ad-libbed...
on August 30, 1953, although it was viewable in color only at the network's headquarters. The first nationwide view of NTSC color came on the following January 1 with the coast-to-coast broadcast of the Tournament of Roses Parade
Tournament of Roses Parade
The Tournament of Roses Parade, better known as the Rose Parade, is "America's New Year Celebration", a festival of flower-covered floats, marching bands, equestrians and a college football game on New Year's Day , produced by the non-profit Pasadena Tournament of Roses Association.The annual...
, viewable on prototype color receivers at special presentations across the country.
The first color NTSC television camera 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
Americas
The Americas, or America , are lands in the Western hemisphere, also known as the New World. In English, the plural form the Americas is often used to refer to the landmasses of North America and South America with their associated islands and regions, while the singular form America is primarily...
and Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
. With the advent of digital television
Digital television
Digital television is the transmission of audio and video by digital signals, in contrast to the analog signals used by analog TV...
, analog broadcasts are being phased out. Most U.S. NTSC broadcasters were required by the FCC to shut down their analog transmitters in 2009. Low-power stations
Low-power broadcasting
Low-power broadcasting is electronic broadcasting at very low power and low cost, to a small community area.The terms "low-power broadcasting" and "micropower broadcasting" should not be used interchangeably, because the markets are not the same...
, Class A stations
Class A television service
The class A television service is a system for regulating some low-power television stations in the United States. Class A stations are denoted by the broadcast callsign suffix "-CA" or "-CD" , although very many analog -CA stations have a digital companion channel that was assigned the -LD...
and translators
Broadcast relay station
A broadcast relay station, relay transmitter, broadcast translator , rebroadcaster , or repeater is a broadcast transmitter which relays, repeats, or reflects the signal of another radio station or television station, usually to an area not covered by the signal of the originating station...
were not immediately affected. An analog cut-off date for those stations was not set.
Lines and refresh rate
NTSC color encoding is used with the system MSystem M
System M, sometimes called 525 line, is the analog broadcast television system used in the United States since July 1, 1941, and also in most of the Americas and Caribbean, South Korea, and Taiwan. In addition, Japan uses System J, which is nearly identical to System M. The systems were given...
television signal, which consists of 29.97 interlaced frames of video
Video
Video is the technology of electronically capturing, recording, processing, storing, transmitting, and reconstructing a sequence of still images representing scenes in motion.- History :...
per second
Second
The second is a unit of measurement of time, and is the International System of Units base unit of time. It may be measured using a clock....
, or the nearly identical system J
NTSC-J
NTSC-J is an analog television system and video display standard for the region of Japan.While NTSC-M is an official standard, "J" is more a colloquial indicator as used in Marketing definition but not an official term.-Technical definition:...
in Japan. Each frame consists of a total of 525 scanlines, of which 486 make up the visible raster
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, the pattern of image storage and transmission used in most computer bitmap image systems...
. The remainder (the vertical blanking interval
Vertical blanking interval
The vertical blanking interval , also known as the vertical interval or VBLANK, is the time difference between the last line of one frame or field of a raster display, and the beginning of the first line of the next frame. It is present in analog television, VGA, DVI and other signals. During the...
) are used for synchronization
Synchronization
Synchronization is timekeeping which requires the coordination of events to operate a system in unison. The familiar conductor of an orchestra serves to keep the orchestra in time....
and vertical retrace. This blanking interval was originally designed to simply blank the receiver's CRT to allow for the simple analog circuits and slow vertical retrace of early TV receivers. However, some of these lines now can contain other data such as closed captioning
Closed captioning
Closed captioning is the process of displaying text on a television, video screen or other visual display to provide additional or interpretive information to individuals who wish to access it...
and vertical interval timecode
Vertical interval timecode
Vertical Interval TimeCode is a form of SMPTE timecode embedded as a pair of black-and-white bars in a video signal. These lines are typically inserted into the vertical blanking interval of the video signal...
(VITC). In the complete raster (ignoring half-lines), the even-numbered or 'lower" scanlines (Every other line that would be even if counted in the video signal, e.g. {2,4,6,...,524}) are drawn in the first field, and the odd-numbered or "upper" (Every other line that would be odd if counted in the video signal, e.g. {1,3,5,...,525}) are drawn in the second field, to yield a flicker-free
Flicker fusion threshold
The flicker fusion threshold is a concept in the psychophysics of vision. It is defined as the frequency at which an intermittent light stimulus appears to be completely steady to the observer...
image at the field refresh frequency
Frequency
Frequency is the number of occurrences of a repeating event per unit time. It is also referred to as temporal frequency.The period is the duration of one cycle in a repeating event, so the period is the reciprocal of the frequency...
of approximately 59.94 Hertz
Hertz
The hertz is the SI unit of frequency defined as the number of cycles per second of a periodic phenomenon. One of its most common uses is the description of the sine wave, particularly those used in radio and audio applications....
(actually 60 Hz/1.001). For comparison, 576i systems
576i
576i is a standard-definition video mode used in PAL and SECAM countries. In digital applications it is usually referred to as "576i", in analogue contexts it is often quoted as "625 lines"...
such as PAL-B/G
PAL
PAL, short for Phase Alternating Line, is an analogue television colour encoding system used in broadcast television systems in many countries. Other common analogue television systems are NTSC and SECAM. This page primarily discusses the PAL colour encoding system...
and SECAM
SECAM
SECAM, also written SÉCAM , is an analog color television system first used in France....
uses 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
Utility frequency
The utility frequency, line frequency or mains frequency is the frequency at which alternating current is transmitted from a power plant to the end-user. In most parts of the world this is 50 Hz, although in the Americas it is typically 60 Hz...
of alternating current
Alternating current
In alternating current the movement of electric charge periodically reverses direction. In direct current , the flow of electric charge is only in one direction....
power used in the United States. Matching the field refresh rate
Refresh rate
The refresh rate is the number of times in a second that a display hardware draws the data...
to the power source avoided intermodulation
Intermodulation
Intermodulation or intermodulation distortion is the amplitude modulation of signals containing two or more different frequencies in a system with nonlinearities...
(also called beating), which produces rolling bars on the screen. When color was later added to the system, the refresh frequency was shifted slightly downward to 59.94 Hz to eliminate stationary dot patterns in the difference frequency between the sound and color carriers, as explained below in "Color encoding". Synchronization of the refresh rate to the power incidentally helped kinescope
Kinescope
Kinescope , shortened to kine , also known as telerecording in Britain, is a recording of a television program made by filming the picture from a video monitor...
cameras record early live television broadcasts, as it was very simple to synchronize a film
Film
A film, also called a movie or motion picture, is a series of still or moving images. It is produced by recording photographic images with cameras, or by creating images using animation techniques or visual effects...
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. By the time the frame rate changed to 29.97 Hz for 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 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
Vacuum tube
In electronics, a vacuum tube, electron tube , or thermionic valve , reduced to simply "tube" or "valve" in everyday parlance, is a device that relies on the flow of electric current through a vacuum...
multivibrator
Multivibrator
A multivibrator is an electronic circuit used to implement a variety of simple two-state systems such as oscillators, timers and flip-flops. It is characterized by two amplifying devices cross-coupled by resistors or capacitors...
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 the problems of thermal drift with vacuum tube devices. The closest practical sequence to 500 that meets these criteria was 3 × 5 × 5 × 7 = 525. (For the same reason, 625-line PAL-B/G and SECAM uses 5 × 5 × 5 × 5, the old British 405-line system used 3 × 3 × 3 × 3 × 5, the French 819-line system used 3 × 3 × 7 × 13 etc.).
Colorimetry
The original 1953 color NTSC specification, still part of the United States Code of Federal RegulationsCode of Federal Regulations
The Code of Federal Regulations is the codification of the general and permanent rules and regulations published in the Federal Register by the executive departments and agencies of the Federal Government of the United States.The CFR is published by the Office of the Federal Register, an agency...
, defined the colorimetric
Colorimetry
Colorimetry is "the science and technology used to quantify and describe physically the human color perception."It is similar to spectrophotometry, but is distinguished by its interest in reducing spectra to the physical correlates of color perception, most often the CIE 1931 XYZ color space...
values of the system as follows:
| Original NTSC colorimetry (1953) | CIE 1931 x | CIE 1931 y |
|---|---|---|
| primary red | 0.67 | 0.33 |
| primary green | 0.21 | 0.71 |
| primary blue | 0.14 | 0.08 |
| white point (CIE Standard illuminant Standard illuminant A standard illuminant is a theoretical source of visible light with a profile which is published. Standard illuminants provide a basis for comparing images or colors recorded under different lighting.-CIE illuminants:... C) |
0.310 | 0.316 |
Early color television receivers, such as the RCA CT-100
Ct-100
For the Bajaj motorcycle, see Bajaj CT 100Introduced in April 1954 the RCA CT-100 was the second all-electronic consumer color television set in the USA, preceeded by the Westinghouse H840CK15 by a few weeks. The color picture tube measured 15 inches diagonally. The viewable picture was just...
, were faithful to this specification, having a larger gamut than most of today's monitors. Their low-efficiency phosphors however were dark 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 both at the receiver and broadcaster ends was the source of considerable color variation.
Color correction in studio monitors and home receivers
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 receiver. 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 luminanceLuma (video)
In video, luma, sometimes called luminance, represents the brightness in an image . Luma is typically paired with chrominance. Luma represents the achromatic image without any color, while the chroma components represent the color information...
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
Video monitor
A video monitor also called a broadcast monitor, broadcast reference monitor or just reference monitor, is a display device similar to a television set, used to monitor the output of a video-generating device, such as playout from a video server, IRD, video camera, VCR, or DVD player. It may or...
s. This specification survives today as the SMPTE "C" phosphor specification:
| SMPTE "C" colorimetry | CIE 1931 x | CIE 1931 y |
|---|---|---|
| primary red | 0.630 | 0.340 |
| primary green | 0.310 | 0.595 |
| primary blue | 0.155 | 0.070 |
| white point (CIE illuminant Standard illuminant A standard illuminant is a theoretical source of visible light with a profile which is published. Standard illuminants provide a basis for comparing images or colors recorded under different lighting.-CIE illuminants:... D65) |
0.3127 | 0.3290 |
As with home receivers, it was further recommended 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 (SMPTE) Committee on Television Technology, Working Group on Studio Monitor Colorimetry, adopted the SMPTE C (Conrac) phosphors for general use in Recommended Practice 145, prompting many manufacturers to modify their camera designs to directly encode for SMPTE "C" colorimetry without color correction., as approved in SMPTE standard 170M, "Composite Analog Video Signal — NTSC for Studio Applications" (1994). As a consequence, the ATSC
ATSC
ATSC standards are a set of standards developed by the Advanced Television Systems Committee for digital television transmission over terrestrial, cable, and satellite networks....
digital television standard states that for 480i
480i
480i is the shorthand name for a video mode, namely the US NTSC television system or digital television systems with the same characteristics. The i, which is sometimes uppercase, stands for interlaced, the 480 for a vertical frame resolution of 480 lines containing picture information; while NTSC...
signals, SMPTE "C" colorimetry should be assumed unless colorimetric data is included in the transport stream.
Variations
Japanese NTSC uses the same colorimetric values for red, blue, and green, but employs a different white point of CIE Illuminant D93 (x=0.285, y=0.293). Both the PAL and SECAM systems used the original 1953 NTSC colorimetry as well until 1970; unlike NTSC, however, the European Broadcasting Union (EBU) eschewed 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, further improving the color fidelity of those systems.Color encoding
For backward compatibility with black-and-white television, NTSC uses a luminance-chrominanceChrominance
Chrominance is the signal used in video systems to convey the color information of the picture, separately from the accompanying luma signal . Chrominance is usually represented as two color-difference components: U = B' − Y' and V = R' − Y'...
encoding system invented in 1938 by Georges Valensi
Georges Valensi
Georges Valensi was a French telecommunications engineer who, in 1938, invented and patented a method of transmitting color images so that they could be received on both color and black & white television sets....
. Luminance (derived mathematically from the composite color signal) takes the place of the original monochrome signal. Chrominance carries color information. This allows black-and-white receivers to display NTSC signals simply by filtering out the chrominance. If it were not removed, the picture would be covered with dots (a result of chroma being interpreted as luminance). All black-and-white TVs sold in the US 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 would show up in the picture.
In NTSC, chrominance is encoded using two 3.579545 MHz signals that are 90 degrees out of phase, known as I (in-phase) and Q (quadrature) QAM. These two signals are each amplitude modulated and then added together. The carrier is suppressed. Mathematically, the result can be viewed as a single sine wave with varying phase relative to a reference and varying amplitude. The phase represents the instantaneous color hue captured by a TV camera, and the amplitude represents the instantaneous color saturation.
For a TV to recover hue information from the I/Q phase, it must have a zero phase reference to replace the suppressed carrier. It also needs a reference for amplitude to recover the saturation information. So, the NTSC signal includes a short sample of this reference signal, known as the color burst, located on the 'back porch' of each horizontal line (the time between the end of the horizontal synchronization pulse and the end of the blanking 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 it synchronizes to the color bursts and then uses as a reference for decoding the chrominance. By comparing the reference signal derived from color burst to the chrominance signal's amplitude and phase at a particular point in the raster scan, the device determines what chrominance to display at that point. Combining that with the amplitude of the luminance signal, the receiver calculates what color to make the point, i.e. the point at the instantaneous position of the continuously scanning beam. Note that analog TV is discrete in the vertical dimension (there are distinct lines) but continuous in the horizontal dimension (every point blends into the next with no boundaries), hence there are no pixel
Pixel
In digital imaging, a pixel, or pel, is a single point in a raster image, or the smallest addressable screen element in a display device; it is the smallest unit of picture that can be represented or controlled....
s in analog TV. In CRT televisions, the NTSC signal is turned into RGB, which is then used to control the electron guns. Digital TV sets receiving analog signals instead convert the picture into discrete pixels. This process of discretization
Discretization
In mathematics, discretization concerns the process of transferring continuous models and equations into discrete counterparts. This process is usually carried out as a first step toward making them suitable for numerical evaluation and implementation on digital computers...
necessarily degrades the picture information somewhat, though with small enough pixels the effect may be imperceptible. Digital sets include all sets with a matrix of discrete pixels built into the display device, such as LCD, plasma, and DLP screens, but not CRTs, which do not have fixed pixels. This should not be confused with digital (ATSC) television signals, which are a form of MPEG video, but which still have to be converted into a format the TV can use.
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
Beat (acoustics)
In acoustics, a beat is an interference between two sounds of slightly different frequencies, perceived as periodic variations in volume whose rate is the difference between the two frequencies....
with the sound carrier to produce a dot pattern on the screen. To make the resulting pattern less noticeable, designers adjusted the original 60 Hz field rate down by a factor of 1.001 (0.1%), to approximately 59.94 fields per second. This adjustment ensures that the sums and differences of the sound carrier and the color subcarrier and their multiples (i.e., the intermodulation
Intermodulation
Intermodulation or intermodulation distortion is the amplitude modulation of signals containing two or more different frequencies in a system with nonlinearities...
products of the two carriers) are not exact multiples of the frame rate, which is the necessary condition for the dots to remain stationary on the screen, making them most 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 15750 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 4.5 MHz / 15,750 = 285.71. In the color standard, this becomes rounded to the integer 286, which means the color standard's line rate is 4.5 MHz / 286 = approximately 15,734 lines per second. Maintaining the same number of scan lines per field (and frame), the lower line rate must yield a lower field rate. Dividing (4,500,000 / 286)
lines per second by 262.5 lines per field gives approximately 59.94 fields per second.
Transmission modulation scheme
Television channel
A television channel is a physical or virtual channel over which a television station or television network is distributed. For example, in North America, "channel 2" refers to the broadcast or cable band of 54 to 60 MHz, with carrier frequencies of 55.25 MHz for NTSC analog video and...
as transmitted occupies a total bandwidth of 6 MHz. The actual video signal, which is amplitude-modulated
Amplitude modulation
Amplitude modulation is a technique used in electronic communication, most commonly for transmitting information via a radio carrier wave. AM works by varying the strength of the transmitted signal in relation to the information being sent...
, is transmitted between 500 kHz and 5.45 MHz above the lower bound of the channel. The video carrier
Carrier wave
In telecommunications, a carrier wave or carrier is a waveform that is modulated with an input signal for the purpose of conveying information. This carrier wave is usually a much higher frequency than the input signal...
is 1.25 MHz above the lower bound of the channel. Like most AM signals, the video carrier generates two sideband
Sideband
In radio communications, a sideband is a band of frequencies higher than or lower than the carrier frequency, containing power as a result of the modulation process. The sidebands consist of all the Fourier components of the modulated signal except the carrier...
s, 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-modulated
Quadrature amplitude modulation
Quadrature amplitude modulation is both an analog and a digital modulation scheme. It conveys two analog message signals, or two digital bit streams, by changing the amplitudes of two carrier waves, using the amplitude-shift keying digital modulation scheme or amplitude modulation analog...
with a suppressed carrier. The audio signal is frequency-modulated
Frequency modulation
In telecommunications and signal processing, frequency modulation conveys information over a carrier wave by varying its instantaneous frequency. This contrasts with amplitude modulation, in which the amplitude of the carrier is varied while its frequency remains constant...
, like the audio signals broadcast by FM radio stations
Radio station
Radio broadcasting is a one-way wireless transmission over radio waves intended to reach a wide audience. Stations can be linked in radio networks to broadcast a common radio format, either in broadcast syndication or simulcast or both...
in the 88–108 MHz band, but with a ±25kHz maximum frequency swing, as opposed to ±75kHz as is used on the FM band. 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 MTS
Multichannel television sound
Multichannel television sound, better known as MTS , is the method of encoding three additional channels of audio into an NTSC-format audio carrier.- History :...
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 stereo audio
Stereophonic sound
The term Stereophonic, commonly called stereo, sound refers to any method of sound reproduction in which an attempt is made to create an illusion of directionality and audible perspective...
and/or second audio program
Second audio program
Second audio program , also known as secondary audio programming, is an auxiliary audio channel for analog television that can be broadcast or transmitted both over the air and by cable TV.-Usage:...
signals are used. The same extensions are used in ATSC
ATSC
ATSC standards are a set of standards developed by the Advanced Television Systems Committee for digital television transmission over terrestrial, cable, and satellite networks....
, where the ATSC digital carrier is broadcast at 1.31 MHz above the lower bound of the channel.
The Cvbs (Composite vertical blanking signal) (sometimes called "setup") is a voltage offset between the "black" and "blanking" levels. Cvbs is unique to NTSC. Cvbs has the advantage of making NTSC video more easily separated from its primary sync signals.
Framerate conversion
There is a large difference in framerate between film, which runs at approximately 24.0 frames per second, and the NTSC standard, which runs at approximately 29.97 frames per second.Unlike the 576i video formats, this difference cannot be overcome by a simple speed-up.
A complex process called "3:2 pulldown" is used. One film frame is transmitted for three video fields (1½ video frame times), and the next frame is transmitted for two video fields (one video frame time). Two film frames are therefore transmitted in five video fields, for an average of 2½ video fields per film frame. The average frame rate is thus 60 / 2.5 = 24 frame/s, so the average film speed is exactly what it should be. There are drawbacks, however. Still-framing on playback can display a video frame with fields from two different film frames, so any motion 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.
For viewing native 576i material (such as European television series and some European movies) on NTSC equipment, a standards conversion has to take place. There are basically two ways to accomplish this:
- The framerate can be slowed from 25 to 23.976 frames per second (a slowdown of about 4%) to subsequently apply 3:2 pulldown.
- Interpolation of the contents of adjacent frames in order to produce new intermediate frames; unless highly sophisticated motion-sensing computer algorithms are applied, this introduces artifacts, and even the most modestly trained of eyes can quickly spot video that has been converted between formats.
Modulation for analog satellite transmission
Because satellite power is severely limited, analog video transmission through satellites differs from terrestrial TV transmission.AM
Amplitude modulation
Amplitude modulation is a technique used in electronic communication, most commonly for transmitting information via a radio carrier wave. AM works by varying the strength of the transmitted signal in relation to the information being sent...
is a linear modulation method, so a given demodulated signal-to-noise ratio
Signal-to-noise ratio
Signal-to-noise ratio is a measure used in science and engineering that compares the level of a desired signal to the level of background noise. It is defined as the ratio of signal power to the noise power. A ratio higher than 1:1 indicates more signal than noise...
(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 FM
Frequency modulation
In telecommunications and signal processing, frequency modulation conveys information over a carrier wave by varying its instantaneous frequency. This contrasts with amplitude modulation, in which the amplitude of the carrier is varied while its frequency remains constant...
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 a 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 or discrete, 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 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's rather like the broken lines running down the middle of a road, it doesn't 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, including the popular DVD
DVD
A DVD is an optical disc storage media format, invented and developed by Philips, Sony, Toshiba, and Panasonic in 1995. DVDs offer higher storage capacity than Compact Discs while having the same dimensions....
format, record NTSC originated video with the even field first in the recorded frame (the development of DVD took place in regions that traditionally utilize NTSC). However, this frame sequence has migrated through to the so-called PAL format (actually a technically incorrect description) of digital video with the result that the even field is often recorded first in the frame (the European 625 line system is specified as odd frame first). This is no longer a matter of convention because a frame of digital video is a distinct entity on the recorded medium. This means that when reproducing many non NTSC based digital formats (including DVD) 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.
Comparative quality
Phase (waves)
Phase in waves is the fraction of a wave cycle which has elapsed relative to an arbitrary point.-Formula:The phase of an oscillation or wave refers to a sinusoidal function such as the following:...
of the color signal (actually differential phase distortion), so the color balance of the picture will be altered unless a compensation is made in the receiver. 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 when channels were changed, which is why NTSC televisions were equipped with a tint control. PAL and SECAM televisions had no need of one, and although it is still found on NTSC TVs, color drifting generally ceased to be a problem once solid-state electronics were adopted in the 1970s. When compared to PAL in particular, NTSC color accuracy and consistency is 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 or Perfection At Last in the color war. This mostly applied to vacuum tube-based TVs, however, and solid state sets 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
SMPTE color bars
The SMPTE color bars are a type of television test pattern, and is most commonly used in countries where the NTSC video standard is dominant, such as those in North America. The Society of Motion Picture and Television Engineers refers to this test pattern as Engineering Guideline EG 1-1990...
, 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
S-Video
Separate Video, more commonly known as S-Video and Y/C, is often referred to by JVC as both an S-VHS connector and as Super Video. It is an analog video transmission scheme, in which video information is encoded on two channels: luma and chroma...
systems completely eliminates the phase distortions. As a consequence, the use of NTSC color encoding gives the highest resolution picture quality (on the horizontal axis & frame rate) of the three color systems when used with this scheme. (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. Some home computers in the 1980s generated S-video, but only for specially designed monitors as no TV at the time supported it. In 1987, a standardized 4-pin DIN plug was introduced for S-video input with the introduction of S-VHS
S-VHS
S-VHS is an improved version of the VHS standard for consumer-level analog recording videocassettes. It was introduced by JVC in Japan in April 1987 with the HR-S7000 VCR and certain overseas markets soon afterwards...
players, which were the first device produced to use the 4-pin plugs. However, S-VHS never became very popular. Video game consoles in the 1990s began offering S-video output as well.
With the advent of DVD players in the 1990s, component video also began appearing. This provides separate lines for the luminance, red shift, and blue shift. Thus, component produces near-RGB quality video. It also allows 480p progressive-scan video due to the greater bandwidth offered.
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 shift
Pitch shift
Pitch shifting is a sound recording technique in which the original pitch of a sound is raised or lowered. Effects units that raise or lower pitch by a pre-designated musical interval are called "pitch shifters" or "pitch benders".-Pitch/time shifting:...
er) at the price of some jerkiness in the video. See Framerate conversion above.
NTSC-M
Unlike PAL, with its many varied underlying broadcast television systemBroadcast television system
Broadcast television systems are encoding or formatting standards for the transmission and reception of terrestrial television signals. There are three main analog television systems in current use around the world: NTSC, PAL, and SECAM...
s in use throughout the world, NTSC color encoding is invariably used with broadcast system M, giving NTSC-M.
NTSC-J
Only JapanJapan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
's variant "NTSC-J
NTSC-J
NTSC-J is an analog television system and video display standard for the region of Japan.While NTSC-M is an official standard, "J" is more a colloquial indicator as used in Marketing definition but not an official term.-Technical definition:...
" is slightly different: in Japan, black level and blanking level of the signal are identical (at 0 IRE
IRE (unit)
An IRE is a unit used in the measurement of composite video signals. Its name is derived from the initials of the Institute of Radio Engineers....
), as they are in PAL, while in American NTSC, black level is slightly higher (7.5 IRE
IRE (unit)
An IRE is a unit used in the measurement of composite video signals. Its name is derived from the initials of the Institute of Radio Engineers....
) 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 while the American VHF band uses channels 2-13.
PAL-M (Brazil)
The Brazilian PAL-M system, introduced in 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 colour 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-M (PAL=Phase Alternating Line) specs are:
- Transmission Band UHF/VHF,
- Frame Rate 29.97
- Lines/Field 525/60
- Horizontal Freq. 15.750 kHz
- Vertical Freq. 60 Hz
- Color Sub Carrier 3.575611 MHz
- Video Bandwidth 4.2 MHz
- Sound Carrier Frequency 4.5 MHz
- Channel Bandwidth 6 MHz
- NTSC (National Television System Committee) specs are:
- Transmission Band UHF/VHF
- Lines/Field 525/60
- Horizontal Frequency 15.734 kHz
- Vertical Frequency 60 Hz
- Color Subcarrier Frequency 3.579545 MHz
- Video Bandwidth 4.2 MHz
- Sound Carrier Frequency 4.5 MHz
PAL-N
This is used in ParaguayParaguay
Paraguay , officially the Republic of Paraguay , is a landlocked country in South America. It is bordered by Argentina to the south and southwest, Brazil to the east and northeast, and Bolivia to the northwest. Paraguay lies on both banks of the Paraguay River, which runs through the center of the...
, Uruguay
Uruguay
Uruguay ,officially the Oriental Republic of Uruguay,sometimes the Eastern Republic of Uruguay; ) is a country in the southeastern part of South America. It is home to some 3.5 million people, of whom 1.8 million live in the capital Montevideo and its metropolitan area...
and Argentina
Argentina
Argentina , officially the Argentine Republic , is the second largest country in South America by land area, after Brazil. It is constituted as a federation of 23 provinces and an autonomous city, Buenos Aires...
. This is very similar to PAL-M
PAL-M (television)
PAL-M is the TV system used in Brazil since February 19, 1972. At that time, Brazil was the first South American country to broadcast in colour. Colour TV broadcast began on September 1972 when the TV networks Globo, Tupi and Bandeirantes TV transmitted the Caxias do Sul Grape Festival. Transition...
(used in Brazil
Brazil
Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...
).
The similarities of NTSC-M and NTSC-N can be seen on the ITU identification scheme table, which is reproduced here:
| System | Lines | Frame rate | Channel b/w | Visual b/w | Sound offset | Vestigial sideband | Vision mod. | Sound mod. | Notes |
|---|---|---|---|---|---|---|---|---|---|
| M | 525 | 29.97 | 6 | 4.2 | +4.5 | 0.75 | Neg. | FM | Most of the Americas Americas The Americas, or America , are lands in the Western hemisphere, also known as the New World. In English, the plural form the Americas is often used to refer to the landmasses of North America and South America with their associated islands and regions, while the singular form America is primarily... and Caribbean Caribbean The Caribbean is a crescent-shaped group of islands more than 2,000 miles long separating the Gulf of Mexico and the Caribbean Sea, to the west and south, from the Atlantic Ocean, to the east and north... , South Korea South Korea The Republic of Korea , , is a sovereign state in East Asia, located on the southern portion of the Korean Peninsula. It is neighbored by the People's Republic of China to the west, Japan to the east, North Korea to the north, and the East China Sea and Republic of China to the south... , Taiwan Republic of China The Republic of China , commonly known as Taiwan , is a unitary sovereign state located in East Asia. Originally based in mainland China, the Republic of China currently governs the island of Taiwan , which forms over 99% of its current territory, as well as Penghu, Kinmen, Matsu and other minor... , Philippines Philippines The Philippines , officially known as the Republic of the Philippines , is a country in Southeast Asia in the western Pacific Ocean. To its north across the Luzon Strait lies Taiwan. West across the South China Sea sits Vietnam... (all NTSC-M) and Brazil Brazil Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people... (PAL-M). |
| N | 625 | 25 | 6 | 4.2 | +4.5 | 0.75 | Neg. | FM | Argentina Argentina Argentina , officially the Argentine Republic , is the second largest country in South America by land area, after Brazil. It is constituted as a federation of 23 provinces and an autonomous city, Buenos Aires... , Paraguay Paraguay Paraguay , officially the Republic of Paraguay , is a landlocked country in South America. It is bordered by Argentina to the south and southwest, Brazil to the east and northeast, and Bolivia to the northwest. Paraguay lies on both banks of the Paraguay River, which runs through the center of the... , Uruguay Uruguay Uruguay ,officially the Oriental Republic of Uruguay,sometimes the Eastern Republic of Uruguay; ) is a country in the southeastern part of South America. It is home to some 3.5 million people, of whom 1.8 million live in the capital Montevideo and its metropolitan area... (all PAL-N). Greater number of lines results in higher quality. |
As it is shown, aside from the number of lines and frames per second
Frame rate
Frame rate is the frequency at which an imaging device produces unique consecutive images called frames. The term applies equally well to computer graphics, video cameras, film cameras, and motion capture systems...
, the systems are identical. NTSC-N/PAL-N are compatible with sources such as game consoles, VHS
VHS
The Video Home System is a consumer-level analog recording videocassette standard developed by Victor Company of Japan ....
/Betamax
Betamax
Betamax was a consumer-level analog videocassette magnetic tape recording format developed by Sony, released on May 10, 1975. The cassettes contain -wide videotape in a design similar to the earlier, professional wide, U-matic format...
VCRs, and DVD
DVD
A DVD is an optical disc storage media format, invented and developed by Philips, Sony, Toshiba, and Panasonic in 1995. DVDs offer higher storage capacity than Compact Discs while having the same dimensions....
players. However, they are not compatible with broadband
Broadband
The term broadband refers to a telecommunications signal or device of greater bandwidth, in some sense, than another standard or usual signal or device . Different criteria for "broad" have been applied in different contexts and at different times...
broadcasts (which are received over an antenna
Antenna (radio)
An antenna is an electrical device which converts electric currents into radio waves, and vice versa. It is usually used with a radio transmitter or radio receiver...
), 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-60PAL
PAL, short for Phase Alternating Line, is an analogue television colour encoding system used in broadcast television systems in many countries. Other common analogue television systems are NTSC and SECAM. This page primarily discusses the PAL colour encoding system...
, 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 (usually multi-standard TVs). Using a native NTSC TV to decode the signal yields no color, while using a PAL TV to decode the system yields erratic colors (observed to be lacking red and flickering randomly). The format is apparently limited to few early 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 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.
NTSC-movie
NTSC with a frame rate of 23.976 frame/s is described in the NTSC-movie standard.Canada/U.S. video game region
Sometimes NTSC-US or NTSC-U/C is used to describe the video gaming region of North America (the U/C refers to U.S. + Canada), as regional lockoutRegional lockout
Regional lockout is the programming practice, code, chip, or physical barrier used to prevent the playing of media designed for a device from the country where it is marketed on the version of the same device marketed in another country.-Video games:...
usually restricts games released within a region to that region.
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 IntervalVertical blanking interval
The vertical blanking interval , also known as the vertical interval or VBLANK, is the time difference between the last line of one frame or field of a raster display, and the beginning of the first line of the next frame. It is present in analog television, VGA, DVI and other signals. During the...
, 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 color burst signal, and the other two having 50 percent and 7.5 percent luminance respectively.
A less-used successor to VIR, GCR
Ghost-canceling reference
Ghost-canceling reference, or GCR, is a special sub-signal on a television channel that receivers can use to attenuate the ghosting effect of a television signal split into multiple paths between transmitter and receiver....
, also added ghost (multipath interference) removal capabilities.
The remaining vertical blanking interval
Vertical blanking interval
The vertical blanking interval , also known as the vertical interval or VBLANK, is the time difference between the last line of one frame or field of a raster display, and the beginning of the first line of the next frame. It is present in analog television, VGA, DVI and other signals. During the...
lines are typically used for datacasting
Datacasting
Datacasting is the broadcasting of data over a wide area via radio waves. It most often refers to supplemental information sent by television stations along with digital television, but may also be applied to digital signals on analog TV or radio...
or ancillary data such as video editing timestamps (vertical interval timecode
Vertical interval timecode
Vertical Interval TimeCode is a form of SMPTE timecode embedded as a pair of black-and-white bars in a video signal. These lines are typically inserted into the vertical blanking interval of the video signal...
s or SMPTE timecodes on lines 12–14), test data on lines 17–18, a network source code on line 20 and closed captioning
Closed captioning
Closed captioning is the process of displaying text on a television, video screen or other visual display to provide additional or interpretive information to individuals who wish to access it...
, XDS
Extended Data Services
Extended Data Services , is an American standard classified under Electronic Industries Alliance standard CEA-608-E for the delivery of any ancillary data to be sent with an analog television program, or any other NTSC video signal.XDS is used by TV stations, TV networks, and TV program...
, and V-chip
V-chip
V-chip is a generic term for technology used in television set receivers in the USA, Canada, and Brazil which allows the blocking of programs based on their ratings category. It is intended for use by parents to manage their children's television viewing...
data on line 21
EIA-608
EIA-608, also known as line 21 captions, used to be the standard for closed captioning for NTSC TV broadcasts in the United States and Canada...
. Early teletext
Teletext
Teletext is a television information retrieval service developed in the United Kingdom in the early 1970s. It offers a range of text-based information, typically including national, international and sporting news, weather and TV schedules...
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 (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
DirecTV
DirecTV is an American direct broadcast satellite service provider and broadcaster based in El Segundo, California. Its satellite service, launched on June 17, 1994, transmits digital satellite television and audio to households in the United States, Latin America, and the Anglophone Caribbean. ...
and CFPL-TV
CFPL-TV
CFPL-DT is a television station based in London, Ontario, Canada, owned by Bell Media. Part of the CTV Two television system, the station serves London, Sarnia and much of southwestern Ontario north of London, including Wingham since its former sister station, CKNX-TV which ceased operations and...
.
TiVo data is also transmitted on some commercials and program advertisements so customers can autorecord the program being advertised, and is also used in weekly half-hour paid programs
Infomercial
Infomercials are direct response television commercials which generally include a phone number or website. There are long-form infomercials, which are typically between 15 and 30 minutes in length, and short-form infomercials, which are typically 30 seconds to 120 seconds in length. Infomercials...
on Ion Television and the Discovery Channel
Discovery Channel
Discovery Channel is an American satellite and cable specialty channel , founded by John Hendricks and distributed by Discovery Communications. It is a publicly traded company run by CEO David Zaslav...
which highlight TiVo promotions and advertisers.
North America
, Over-the-air NTSC broadcasting in major cities only scheduled to be abandoned by August 2011, simulcast in ATSC, Over-the-air NTSC broadcasting scheduled to be abandoned by December 31, 2015 simulcast in ATSC, High-power over-the-air NTSC broadcasting was switched off on June 12, 2009 in favor of ATSC. Low-power stationsLow-power broadcasting
Low-power broadcasting is electronic broadcasting at very low power and low cost, to a small community area.The terms "low-power broadcasting" and "micropower broadcasting" should not be used interchangeably, because the markets are not the same...
, Class A stations
Class A television service
The class A television service is a system for regulating some low-power television stations in the United States. Class A stations are denoted by the broadcast callsign suffix "-CA" or "-CD" , although very many analog -CA stations have a digital companion channel that was assigned the -LD...
and translators
Broadcast relay station
A broadcast relay station, relay transmitter, broadcast translator , rebroadcaster , or repeater is a broadcast transmitter which relays, repeats, or reflects the signal of another radio station or television station, usually to an area not covered by the signal of the originating station...
are not immediately affected, nor are remaining analog cable television
Cable television
Cable television is a system of providing television programs to consumers via radio frequency signals transmitted to televisions through coaxial cables or digital light pulses through fixed optical fibers located on the subscriber's property, much like the over-the-air method used in traditional...
systems. NTSC also remains in use as an interconnect standard for A/V devices such as televisions and DVD players.
Central America
, NTSC broadcast to be abandoned by December 2018, simulcasting ISDB-T/b, Over-the-air NTSC broadcasting scheduled to be abandoned by January 1, 2019 simulcast in ATSC, Over-the-air NTSC broadcasting scheduled to be abandoned by December 2020, simulcast in ATSC
Caribbean islands
(U.S.)South America
, NTSC broadcast to be abandoned by 2019, simulcasting DVB-TDVB-T
DVB-T is an abbreviation for Digital Video Broadcasting — Terrestrial; it is the DVB European-based consortium standard for the broadcast transmission of digital terrestrial television that was first published in 1997 and first broadcast in the UK in 1998...
, NTSC broadcast to be abandoned by December 31, 2017, simulcasting ISDB-T/b, NTSC broadcast to be abandoned by December 31, 2017, simulcasting ISDB-T/b
Asia
, NTSC-J broadcast was switched off on July 24, 2011, simulcasting ISDBISDB
Integrated Services Digital Broadcasting is a Japanese standard for digital television and digital radio used by the country's radio and television stations. ISDB replaced the previously used MUSE "Hi-vision" analogue HDTV system...
-T, but some area will be delayed due to 2011 Miyagi earthquake, NTSC broadcast to be abandoned by December 2012, simulcast in ATSC Republic of China
Republic of China
The Republic of China , commonly known as Taiwan , is a unitary sovereign state located in East Asia. Originally based in mainland China, the Republic of China currently governs the island of Taiwan , which forms over 99% of its current territory, as well as Penghu, Kinmen, Matsu and other minor...
(Taiwan
Taiwan
Taiwan , also known, especially in the past, as Formosa , is the largest island of the same-named island group of East Asia in the western Pacific Ocean and located off the southeastern coast of mainland China. The island forms over 99% of the current territory of the Republic of China following...
), NTSC broadcast to be abandoned by June 30, 2012, simulcast in DVB-T Union of Burma, NTSC broadcast to be abandoned by December 2015. Simulcast in ISDB-T
Other: (Only for few satellite TV programs; mostly are changed into PAL) (Propaganda station aimed at South Korea; domestic broadcasts use PAL) (Historic; Cambodia now uses PAL)
, Former used shortly by Thai TV Channel 4 Bangkunbrohma; later changed to PAL in late 1960s.
Chilean territories
, NTSC-M broadcast to be abandoned by December 31, 2017, simulcasting ISDB-T/bOther Pacific island nations
(in Compact of Free AssociationCompact of Free Association
The Compact of Free Association defines the relationship that three sovereign states—the Federated States of Micronesia , the Republic of the Marshall Islands and the Republic of Palau—have entered into as associated states with the United States.Now sovereign nations, the three freely associated...
with U.S.; U.S. aid funded NTSC adoption) Micronesia
Federated States of Micronesia
The Federated States of Micronesia or FSM is an independent, sovereign island nation, made up of four states from west to east: Yap, Chuuk, Pohnpei and Kosrae. It comprises approximately 607 islands with c...
(in Compact of Free Association
Compact of Free Association
The Compact of Free Association defines the relationship that three sovereign states—the Federated States of Micronesia , the Republic of the Marshall Islands and the Republic of Palau—have entered into as associated states with the United States.Now sovereign nations, the three freely associated...
with U.S.) (in Compact of Free Association
Compact of Free Association
The Compact of Free Association defines the relationship that three sovereign states—the Federated States of Micronesia , the Republic of the Marshall Islands and the Republic of Palau—have entered into as associated states with the United States.Now sovereign nations, the three freely associated...
with U.S.; adopted NTSC before independence) (closely tied to American Samoa; U.S. aid funded NTSC adoption) (U.S. aid funded NTSC adoption)
Historic (used NTSC experimentally before adopting PAL)
United Kingdom (tests using 405-line405-lineThe 405-line monochrome analogue television broadcasting system was the first fully electronic television system to be used in regular broadcasting....
50 Hz system in the late 1950s before the introduction of PAL Color and 625/50 Hz in the 1960s).
Republic of Ireland (Same as above) .
See also
- Broadcast television systems
- ATSC Standards
- BTSC
- NTSC-JNTSC-JNTSC-J is an analog television system and video display standard for the region of Japan.While NTSC-M is an official standard, "J" is more a colloquial indicator as used in Marketing definition but not an official term.-Technical definition:...
- NTSC-CNTSC-CNTSC-C is a regional lockout created in 2003 by Sony Computer Entertainment for the official launch of its PS2 gaming system into the mainland Chinese market.-Mainland Chinese market:...
- PALPALPAL, short for Phase Alternating Line, is an analogue television colour encoding system used in broadcast television systems in many countries. Other common analogue television systems are NTSC and SECAM. This page primarily discusses the PAL colour encoding system...
- RCARCARCA Corporation, founded as the Radio Corporation of America, was an American electronics company in existence from 1919 to 1986. The RCA trademark is currently owned by the French conglomerate Technicolor SA through RCA Trademark Management S.A., a company owned by Technicolor...
- SECAMSECAMSECAM, also written SÉCAM , is an analog color television system first used in France....
- List of video connectors
- Moving image formatsMoving image formatsThis article discusses moving image capture, transmission and presentation from today's technical and creative points of view; concentrating on aspects of frame rates.- Essential parameters :...
- Oldest television stationOldest television stationThis is a list of prewar television stations of the 1920s and 1930s that were among the first in the world. Most of these experimental stations were located in Europe , Canada and the United States...
- Television channel frequenciesTelevision channel frequenciesThe following tables show the frequencies assigned to broadcast television channels in various regions of the world, along with the ITU letter designator for the system used. The frequencies shown are for the video and audio carriers. The channel itself occupies several megahertz of bandwidth....
- Very high frequencyVery high frequencyVery high frequency is the radio frequency range from 30 MHz to 300 MHz. Frequencies immediately below VHF are denoted High frequency , and the next higher frequencies are known as Ultra high frequency...
- Ultra high frequencyUltra high frequencyUltra-High Frequency designates the ITU Radio frequency range of electromagnetic waves between 300 MHz and 3 GHz , also known as the decimetre band or decimetre wave as the wavelengths range from one to ten decimetres...
- Knife-edge effectKnife-edge effectIn electromagnetic wave propagation, the knife-edge effect or edge diffraction is a redirection by diffraction of a portion of the incident radiation that strikes a well-defined obstacle such as a mountain range or the edge of a building....
- Channel 1 (NTSC-M)
- Channel 37Channel 37Channel 37 is an unused television channel in countries using the M and N broadcast television system standards. Channel 37 occupies a band of UHF frequencies from 608 to 614 MHz, frequencies that are particularly important to radio astronomy...
- North American broadcast television frequenciesNorth American broadcast television frequenciesThe North American broadcast television frequencies are on designated television channels numbered 2 through 69, approximately between 54 and 806 MHz. Traditionally, the frequencies are divided into two sections, the very high frequency band and the ultra high frequency band. The VHF band is...
- North American cable television frequenciesNorth American cable television frequenciesIn North American cable TV networks, the radio frequencies used to carry signals to the customer are allocated to standardarized channel numbers listed in the CEA standard 542. Cable channel frequencies are generally different from off-air broadcast frequencies...
- Australasian TV frequencies
- Very high frequency
- Broadcast-safeBroadcast-safeBroadcast-safe video is a term used in the broadcast industry to define video and audio compliant with the technical or regulatory broadcast requirements of the target area or region the feed might be broadcasting to...
- DTV transition in the United StatesDTV transition in the United StatesThe DTV transition in the United States was the switchover from analog to exclusively digital broadcasting of free over-the-air television programming...
External links
- U.S. cable television channel frequencies
- TVTower.com - Commercial Television Frequencies
- Representation of the NTSC refresh rate on a television and on a DVD
- Understanding & Measuring Video TV-RF Signals by Glen Kropuenske, CET, Sencore Application Engineer