NTSC

NTSCSECAMPAL or PAL/SECAMNo InformationUse of NTSC as Official Standard in the World (Color Verde). Distribution of TV Systems in the World

NTSC named for the acronym of National Television System Committee, (in Spanish Comité Nacional de Sistema de Televisión) is the system analog television that has been used in North America, Central America, most of South America and Japan among others. A derivative of NTSC is the PAL system that is used in Europe and some South American countries such as Argentina, Paraguay, Uruguay and Brazil.

History

In July 1940, in the United States, the Radio Manufacturers Association (RMA, acronym for the Radio Manufacturers Association) established a Television System Committee Committee (NTSC) chaired by electrical engineer Walter Ransom Gail Baker (1892-1960), who was manager of General Electric's radio and television division. After several hours of technical work done by this committee, the Federal Commission The FCC held public hearings beginning on March 20, 1941, finding that the standards the committee proposed had been approved virtually unanimously by manufacturers. The NTSC committee selected 525 scan lines as a compromise between RCA's standard of 441 scan lines, which was already being used by RCA's NBC television network, and the wishes of manufacturers Philco and DuMont to increase that number to between 605 and 800 lines. The standard recommended an output rate of 30 images per second, each consisting of two interlaced fields per frame at 262.5 lines per field and 60 fields per second. Other standards in the final recommendations were to maintain a 4:3 aspect ratio, and to frequency modulate the audio carrier, which was fairly recent at the time. In its report dated May 3, 1941, the FCC accepted the committee's recommendations and approved commercial television broadcasts, under NTSC standards, on July 1, 1941.

In January 1950, the Committee was reconstituted to standardize color television. Nine months later, the FCC had quickly approved a standard that was developed by CBS. However, this standard was incompatible with black-and-white transmissions and receivers at the time. The CBS system used a rotating color wheel, reduced the number of scan lines from 525 to 405, and increased the field frequency from 60 to 144 Hz, but had an effective frame rate of only 24 frames. per second. Legal action by rival RCA kept commercial use of the system off the air until June 1951, and its regular broadcasts only lasted a few months, before manufacture of all color televisions was banned by the Office of Defense Mobilization (ODM), in October, apparently due to the Korean War.

During 1951, engineers from RCA and General Electric filed patent applications for color control systems in what would become the future NTSC standard, such as the Americans Eugene Orville Keizer, Robert Dome, Loren R. Kirkwood, Alton J. Torre and Richard W. Sonnenfeldt. Kirkwood and Torre proposed in their patent application the frequency of 3.89 MHz for the color burst signal frequency for the synchronization of color signals, using the circuit of quadrature modulator that appeared in the November 1949 issue of "Electronics" From McGraw-Hill Publishing.

CBS terminated its system in March 1953, and the FCC replaced it on December 17, 1953, with the NTSC color standard, which had been developed cooperatively by several companies, including RCA and Philco.

In December 1953, what is now known as the NTSC color television standard, later defined as RS-170A, was unanimously approved. The "compatible color" it maintained full backwards compatibility with existing black and white television sets.

The color information was added to the black and white image by adding a color subcarrier of 4.5 × 455/572 = 315/88 MHz=3.579545455 (approximately 3.58 MHz) to the video signal. To reduce the visibility of interference between the chrominance signal and the FM sound carrier, a slight reduction in frame rate from 30 to approximately 29.97 frames per second and changing the line frequency to 15750 Hz was required. at approximately 15734.26 Hz.

The first public broadcast of a program using the "color compatible" NTSC, was an episode of the NBC children's show Kukla, Fran and Ollie that aired on August 30, 1953, though it was viewable in color only at the station's headquarters. Nationally viewable broadcast of NTSC in color was made on the January 1, 1954, coast-to-coast broadcast of the Rose Parade, and could be seen on prototype color receivers at special appearances across the country.

The first television camera for the NTSC color standard was the RCA TK-40, used for experimental broadcasts in 1953 and an improved version, the TK-40A, introduced in March 1954, which was the first color camera. commercially available color television. Later that year, the improved TK-41 camera became the standard camera used throughout much of the 1960s in America.

The NTSC standard has been adopted by other countries, most of the Americas and Japan. With the advent of digital television, analog broadcasts are being phased out in the United States, while in other countries this change will take some time. The FCC ordered most NTSC stations in the US to shut down their analog transmitters in 2009. Low-power stations, Class A stations, and rebroadcast stations were immediately affected. Ultimately, the FCC ruled that On September 1, 2015, all analog television services in the United States would end, including those of low-power stations, so users in that country had to purchase decoding equipment for their traditional televisions or new equipment with a digital tuner.

Technical details

Line and update frequency

The NTSC System color coding is used with Television Standard M, which is 29.97 video frames per second with interlaced scanning. Each raster or frame is made up of two fields, each of which consists of 262.5 scan lines, for a total of 525 scan lines, of which 480 make up the visible frame. The remainder, during the vertical blanking interval, is used for sync and vertical retrace. This interval was originally designed to blank the CRT of early television receivers. However, some of these lines may now contain other data such as subtitles and vertical interval time code (VITC). In the full frame, the even scan lines (from 2 to 524) are drawn in the first field and the odd scan lines (from 1 to 525) are drawn in the first field (without taking into account the half lines due to interlacing). second field, to provide a flicker-free image at a refresh rate of approximately 59.94 Hz (actually 60 Hz). For comparison, 576i systems such as PAL-B/G/N and SECAM use 625 lines, of which 576 are visible, thus providing higher vertical resolution, but lower temporal resolution of 25 frames or 50 fields. per second.

The NTSC vertical refresh rate in the black-and-white TV system originally matched exactly the nominal 60 Hz AC frequency used in the United States. Matching the field update rate to the power frequency prevented the intermodulation (or beat) that causes rolling bars on the screen. When color was added to television, the refresh rate was slightly lowered to 59.94 Hz to eliminate stationary dot patterns between the frequency difference between sound and color carriers. The synchronization of the two frequencies, by the way, helped kinescope cameras to record the first live television broadcasts, since it was very simple to synchronize a movie camera to capture a frame of video in each frame of the film using the Using the AC frequency to adjust the speed of the AC synchronous motor of the camera. By the time the frame rate changed to 29.97 frames per second for color systems, it was easier to trigger the camera's shutter from the video feed itself.

The figure of 525 lines was chosen as a result of the limitations of spectrum use. A video signal of 525 lines and 30 frames per second requires a bandwidth of 6 MHz. In the first practical TV systems, a main voltage-controlled oscillator was operated at twice the horizontal line frequency, and this frequency was divided by the number of lines used (in this case 525) to obtain the field frequency (60 Hz). This frequency was then compared to the power line frequency of 60 Hz and any discrepancies were corrected by adjusting the main oscillator frequency. For interlaced scanning, an odd number of lines per frame is required in order to make the vertical return distance identical for odd and even fields, which meant that the master oscillator frequency had to be divided by a number odd. At that time, the only practical method of frequency division was the use of a chain of vacuum tube multivibrators. The total split ratio is the product of the split ratios of the entire chain. Since all the prime factors of an odd number are also odd, it follows that all the divisions of the chain also had to divide by odd numbers, and these had to be relatively small, because harmonic filtering loses performance. The closest practice sequence to 500 that met these criteria was 3 × 5 × 5 × 7 = 525. For the same reason, in European 625-line standards, CCIR Standard (625 lines 25 frames per second) is uses 5 × 5 × 5 × 5; in the old British standard of 405 lines the sequence was 3 × 3 × 3 × 3 × 5 and in the French standard of 819 lines, the ratio 3 × 3 × 7 × 13 was used. The EIA Standards of 525/30 used With a bandwidth of 6 MHz, the CCIR 625/25 occupied 7 or 8 MHz of bandwidth (depending on the standard of each country), while the French standard 819/25 occupied 10 MHz.

Colorimetry

The original NTSC color specification in 1953 defines the system of colorimetric values as follows:

Early color television receivers, such as RCA's CT-100, were true to this specification, with a wider gamut than most monitors today. The phosphor used was, however, of low efficiency, dark and long persistence, leaving trails behind moving objects on the screen. Beginning in the late 1950s, picture tube phosphors would sacrifice saturation for higher brightness; this deviation from the norm at both the receiver and transmitter ends was the source of considerable color variation.

SMPTE C Specification

To ensure the most consistent color reproduction, receivers began to incorporate color correction circuitry that converted the received signal, coded according to the colorimetric values mentioned above, into signals coded from the phosphors actually used in the receiver. Since color correction cannot be accurately performed on the transmitted non-linear (gamma-corrected) signals, the adjustment can only be approximate, introducing hue and luminance errors, as well as errors for highly saturated colors.

Similarly, for the broadcast stage, between 1968 and 1969 the Conrac Corporation, in collaboration with RCA, defined a set of controlled phosphors for use in broadcasting color images from video monitors. This specification remains today as the SMPTE "C" phosphor specifications:

As with receivers for residential use, it was further recommended that similar studio monitors incorporate color correction circuitry so that broadcasters could transmit images encoded to the original 1953 colorimetric values, in accordance with standards of the FCC./

In 1987, the SMPTE Television Technology Committee's Working Group on Studio Monitor Colorimetry adopted the SMPTE-C (Conrac) specification for general use in Recommended Practice 145, which led to many manufacturers to modify your camera designs to encode directly into SMPTE "C" without color correction. as approved in the SMPTE 170M standard titled "Composite Analog Video Signal — NTSC for Studio Applications" (NTSC Composite Analog Video Signal for Studio Applications) published in 1994. As a consequence, the American ATSC digital television standard states that for 480i signals, SMPTE "C" should be assumed unless colorimetric data is included in the transport stream.

The Japanese NTSC version uses the same colorimetric values for red, blue, and green, but employs a different white point from CIE Illuminant D93 (x=0.285, y=0.293). Both the PAL and SECAM systems used the colorimetry original NTSC from 1953, until 1970; however, unlike NTSC, the European Broadcasting Union (EBU) eschewed color correction on receivers and studio monitors that year and instead explicitly called for all equipment to encode signals directly for the "EBU" colorimetric values, further improving the color fidelity of those systems.

Color coding

To maintain compatibility with black-and-white television, the NTSC color standard uses a luminance-chrominance coding system invented in 1938 by French engineer Georges Valensi. Luminance (mathematically derived from the signal composite color) represents the basic monochrome television signal. Color difference or chrominance signals carry color information. This allows monochrome receivers to display station signals in NTSC color, simply by filtering out the chrominance signals. If these are not filtered, the image would be covered in dots, as a result of color signals being interpreted as luminance. All black-and-white televisions manufactured and sold in the US after the introduction of color television in 1953 were designed to filter out color signals.

In NTSC, the chrominance signals are quadrature amplitude modulated to two carrier signals at frequency 3.579545 MHz derived from a master oscillator that are 90 degrees out of phase and are known as the I (in phase, in phase) and Q (in quadrature, in quadrature). These two signals are added to the output of the modulator and the carrier is suppressed. Mathematically, the result can be seen as a single sine wave with various offsets from a reference and with variable amplitude. The phase represents the instantaneous color hue or hue captured by a television camera, and the amplitude represents the instantaneous color saturation.

In order for a television to recover hue information from the I and Q signals, it must have a zero phase reference to replace the suppressed carrier. You also need a reference for the amplitude to retrieve the saturation information. Therefore, the NTSC signal includes a small sample of this reference signal, known as a salvo or color burst, which is found in the so-called rear gate of each horizontal line, which is the time between the end of the horizontal sync pulse and the end of the blanking. The color burst consists of a minimum of eight cycles of the unmodulated color subcarrier, with fixed phase and amplitude. The receiver has a local oscillator, which is synchronized with the color bursts and is used as a reference for chrominance decoding. By comparing the reference signal derived from the color burst with the amplitude and phase of the chrominance signal at a particular point in the raster scan, the device determines the color to display at that point. By combining this with the amplitude of the luminance signal, the receiver calculates the color saturation at the instantaneous position of the continuously scanned beam. It should be noted that analog TV is discrete in the vertical dimension (because it is divided into distinct lines), but it is continuous in the horizontal dimension (each point blends with the next without limits), therefore there are no pixels. on analog television. In cathode ray tube (CRT) televisions, the NTSC signal is converted to RGB, which is then used to control the tube's electron guns.

When a television transmitter broadcasts an NTSC signal, a radio frequency carrier is amplitude modulated with the video signal as just described, while the audio signal frequency modulates a carrier with a frequency of 4.5 MHz higher than the video carrier. If the non-linear distortion is passed to the broadcast signal, the 3.579545 MHz color subcarrier can “beat” into the broadcast signal. with the sound carrier to produce a pattern of dots on the screen. To make the pattern less noticeable, designers adjust the original 60Hz field frequency down by a factor of 0.1%, to approximately 59.94 fields per second. This setting ensures that the sums and differences of the sound carrier and the color subcarrier and their multiples (i.e. the intermodulation products of the two carriers) are not exact multiples of the frame rate, which is the necessary condition for the dots remain stationary on the screen, making them less noticeable.

The designers chose to make the chrominance subcarrier frequency a multiple of "n+0.5" of the line frequency to minimize interference between the luminance signal and the chrominance signals. Another way of expressing this is that the color subcarrier frequency is an odd multiple of half the line frequency. They then opted to make the audio subcarrier frequency an integer multiple of the line frequency to minimize visible interference (intermodulation) between the audio signal and the chrominance signals. The original monochrome standard, with its 15750 Hz line frequency and 4.5 MHz audio subcarrier, does not meet these requirements, so designers had to either increase the audio subcarrier frequency or lower the audio subcarrier frequency. line. Increasing the frequency of the audio subcarrier would prevent existing receivers (black and white) from correctly tuning the audio signal. Line frequency reduction is relatively harmless, because the horizontal and vertical synchronization information in the NTSC signal allows a receiver to tolerate a substantial amount of variation in line frequency. So the NTSC committee engineers opted for a line frequency change in the color standard. In the monochrome standard, the ratio of the audio subcarrier frequency to the line frequency is 4.5 MHz/15,750 kHz ≈ 285.71. In the color standard, this is rounded to the integer 286, which means that the standard color line rate is 4.5 MHz/286 = 15734 lines per second. Keeping the number of lines per field and per frame the same, slowing down the bottom line should produce a lower field speed. Dividing 15,734 lines per second by 262.5 lines per field gives approximately 59.94 fields per second. This explains the slight decrease in the field frequency with respect to the monochromatic standard.

Transmission modulation scheme

Distribution in the spectrum of a television channel in the M System, with color in NTSC standard.

An NTSC television channel occupies a total bandwidth of 6 MHz. The video signal, which is amplitude modulated, is transmitted between 500 kHz and 5.45 MHz above the lower limit of the channel. The video carrier is 1.25 MHz above the lower limit of the channel. As with most AM signals, the video carrier generates two sidebands, one above the carrier and one below it. Each of the sidebands has a width of 4.2 MHz. The entire upper sideband is transmitted, but only 1.25 MHz of the lower sideband, known as the vestigial sideband, is transmitted. The color subcarrier is 3.579545 MHz above the video carrier, and is quadrature amplitude modulated by the chrominance or color difference signals, carrier suppressed. The audio signal is frequency modulated, but with a maximum frequency deviation of ±25 kHz. The audio carrier is 4.5 MHz above the video carrier, so it is 250 kHz below the top of the channel. Sometimes a channel may contain a multi-channel television sound signal, which provides more than one audio signal by adding one or two subcarriers to the audio signal, each clocked to a multiple of the line frequency. This is often the case when using stereo audio signals or a second audio program. Similar extensions are used in the US digital television standard ATSC, in which the digital carrier is transmitted at 1.31 MHz above the lower channel limit.

Comparison in quality

SMPTE Color Bar, an example of a test pattern.

Reception problems could degrade an NTSC picture by shifting the phase of the color signal (actually differential phase distortion), so the picture's color balance would be off unless the receiver set it. make compensation. The vacuum tube electronics used in televisions through the 1960s gave rise to various technical problems. Among other things, the phase of the color burst often varies when changing channels, so NTSC televisions were equipped with a tint control. Although such control is still found on NTSC receivers, color drift generally ceased to be a problem once solid-state electronics were adopted in the 1960s. Color tint or tone control allows anyone to An expert can easily calibrate a monitor using SMPTE color bars, even with a receiver that has drifted in its color representation, allowing proper colors to be displayed. In contrast, on older televisions for the PAL color coding system there was no user-available tint control (as it had been set at the factory), which contributed to its good reputation for color reproduction.

Using separate luminance and chrominance signals as is done in the S-Video system improves color reproduction, since it is not necessary to use filters to separate luminance from chrominance. When using S-Video, you can't talk about NTSC, since it's not a composite video signal. In 1987, a standardized 4-pin DIN plug for S-video input was introduced with the introduction of S-VHS players, which were the first production device to use the 4-pin plugs. However, S-VHS systems never became very popular.

S-Video was normally only found in high-end video (laserdisc) players. In the 1990s, cheaper devices such as DVD players and game consoles began to feature S-Video output. This provides separate connections for luminance and color difference signals. Therefore, the player produces near RGB quality video. It also allows you to record 480 pixel progressive scan video, due to the higher bandwidth offered. The mismatch between NTSC's 30 frames/second and cinema's 24 frames/second is overcome by a process that takes advantage of the field rate of the interlaced NTSC signal, thus avoiding the increased playback speed of film used for 576i systems at 25 frames per second.

Variants of the NTSC System

NTSC-M

NTSC color coding is always used with Broadcast System M, technically known as NTSC-M. It is also used in the Argentine and Brazilian version of PAL color coding, especially for cable and satellite television.

NTSC-N

NTSC-N is a system that combines 625-line video with 3.58 MHz NTSC color. PAL software running on an Atari ST NTSC display uses this system, as it cannot display PAL color. TVs and monitors with a V-Hold knob can display this system after adjusting the vertical hold. PAL-N signals are generically identical to North American NTSC signals, except for the color carrier coding. Both systems are based on the N monochrome standard, therefore PAL-N will display monochrome with sound on NTSC equipment and vice versa. In Argentina, Uruguay and Paraguay it is used for subscription television.

NTSC-J

In the Japanese variant, called NTSC-J, the signal level for black and the signal suppression level are identical (they have the level of 0 IRE), while in the American NTSC system, the level for black it is slightly higher (7.5 IRE) than the suppression level. Since the difference is very small, a slight adjustment of the brightness is all that is required to view color signals of this variant on an American NTSC receiver, and even many viewers see no need to adjust the brightness. The channel coding in NTSC-J differs slightly from NTSC-M. In particular, the Japanese VHF band runs from channels 1-12, which are on the frequencies directly above the Japanese FM radio band 76-90 MHz, while the North American VHF television band uses channels 2 to 13 (54-72 MHz, 76-88 MHz and 174-216 MHz) with 88-108 MHz assigned to FM broadcasting. Therefore, UHF channels from Japan are numbered from channel 13 and not from 14 onwards, as in the US standard.

NTSC 4.43

NTSC 4.43 is a heavyweight color system, used in Europe, that transmits the 525-line, 29.97 fps coding of NTSC on a 4.43 MHz color subcarrier. The resulting output it is only visible on multi-standard TV equipment for the European market. It took advantage of the fact that the luma and chroma separator filters were tuned to 4.43 MHz.

Although the NTSC 4.43 system is not a broadcast format, it typically appeared as an add-on to PAL-standard VCRs, beginning with the U-Matic 3/4" from Sony, then Betamax and VHS sold in Europe and countries that have adopted PAL in its European version. Since American cinema was released on most video cassettes around the world, and since not all releases in that format were available in PAL, it was highly desirable to have the ability to read cassettes recorded in NTSC.

Multi-standard video monitors were already in use in Europe to accommodate broadcast sources in the PAL, SECAM and NTSC video formats. The U-Matic, Betamax, and VHS heterodyne processing for color signals lent itself to minor modification of VCRs to accommodate NTSC-format cassettes. The color process for VHS uses a 629 kHz subcarrier, while U-Matic and Betamax use a 688 kHz subcarrier to carry an amplitude-modulated chroma signal for NTSC and PAL formats. Since VCRs were ready to play the color portion of the NTSC recording using the PAL color mode, the PAL scanner and capstan speeds had to be adjusted from the 50 Hz PAL field frequency to 59 Hz..94 Hz from the NTSC field frequency, and at a faster tape speed. Changes to the PAL VCR are minor thanks to existing VCR recording formats. The VCR output during playback of an NTSC cassette in NTSC 4.43 mode is 525 lines and 29.97 frames per second with 4.43 modulated color signals.

Variants of the PAL System

The original PAL system is PAL-B. It was developed in Germany by Dr. Walter Bruch of the Telefunken company. It basically uses the same principles as the NTSC system, but with the difference that the R-Y color difference signal inverts the phase 180° between one line and the next. Said inversion makes it possible to detect the phase changes of the color vectors and also allows the use of modulation of the color subcarrier in Vestigial Side Band with suppressed carrier and with the same bandwidth for each color difference signal (which is impossible in the NTSC system, which uses the differential bandwidth between the I and Q signals).

PAL-M

The Brazilian PAL-M system, introduced on February 19, 1972, is a redesign of the European PAL standard that uses the same broadcast bandwidth, frame rate, and number of lines, and the same transmission bandwidth. transmission and horizontal scan than the US M broadcast system. USA (EIA). Before the introduction of color TV, in Brazil it was transmitted with this diffusion system. The adoption of the PAL system in the M standard was an attempt by the industry to be able to manufacture all the necessary equipment locally. This strategy failed, and the imported equipment in PAL-M resulted in a higher cost, since it was only produced for Brazil, giving a low manufacturing scale. So the Brazilian television stations decided to produce their programs with NTSC equipment and broadcast in PAL-M through transcoding. The color subcarrier frequency in PAL-M is 3.57561125 MHz.

PAL-N

This variant of the PAL standard was created in Argentina, through Resolution No. 100 ME/76 which determined the creation of a study commission for a local color standard. This commission recommended using the PAL standard under the N diffusion system that Paraguay and Uruguay also used. In these countries, broadcasters produce their programs using PAL equipment under broadcast system B (PAL-B) and then, using a transcoder, switch from PAL-B to PAL-N. These transcoders, designed by Walter Bruch in 1978, use filters to separate the luminance and chrominance signals, allowing maximum use of the original luminance resolution. Experiments at the time showed that better image quality was obtained by this method than directly generating the signal in PAL-N. During the launch of Telefe Internacional in 1998 and El Día del Milenio on Canal 13 (Argentina) in 1999, the stations decided to produce their programs with NTSC equipment and broadcast in PAL-N by transcoding. The color subcarrier frequency in PAL-N is 3.582056 MHz

Disadvantages of the NTSC system in its origins

Transmission and interference problems tend to degrade the image quality of the NTSC system by altering the phase of the color signal, so that sometimes the picture loses its color balance at the time it is received. To correct this, one more control had to be added to this system: the tint control, which was not necessary in PAL or SECAM. This was due to the lack of stability of the components used in the 1950s. That is why, jokingly, it used to be called "NTSC: Never The Same Color", in Spanish "NTSC: never the same color". Later, this problem has been corrected with solid-state and integrated circuits.

Given its characteristics, it offers a color resolution of 525 lines, while the PAL and SECAM systems offer 625/2 since the chrominance is averaged every two lines. Converting film formats to the 29.97 frame/second M standard requires an additional process known as “3:2 pull down”.

Compatibility of B/W and color systems

When the color television signal transmission systems appeared, the black and white system was already widespread and, therefore, it was necessary for the color transmission system to be compatible with existing receivers.

B/W transmission systems are based on the capture by the camera of a luminance signal. On the other hand, in color television transmission systems, it is necessary to specify the color of a picture element by decomposing the three primary colors red (R), green (G) and blue (B).

The system chosen to transmit the signal was the combination of luminance (Y), and two color difference signals R-Y, B-Y. These two difference signals were chosen because they achieve greater protection against interference and noise.

This system meets the basic conditions of compatibility between systems:

• The B/N receptors could reproduce the signal emitted with color information but in B/N.
• Color receptors could reproduce in B/N the signal of stations that still emit monochromatic signals.

Experimental relationship adopted to relate the components: Y(R,G,B)=0'229*R+0'587*G+0'114*B.

This relation allows obtaining in reception the direct conversion of the three components Y, R-Y, B-Y towards those necessary for reproduction R, G, B.

Technical specifications

• Appearance ratio: 4/3
• Number of lines: 525
• Number of active lines: 480
• Frame Frequency: 30 Hz
• Field frequency (image): 60 Hz (59.94 in color version)
• Frequency of the color subporter: 3.579545 MHz
• Sound carrier frequency: 4.5 MHz
• Line period: 64 microseconds
• Active line period: 52 microseconds
• Duration of horizontal synchronism: 4.7 microseconds
• Duration of line deletion: 12 microseconds
• Gamma correction factor: 2,8
• Video signal bandwidth: 4.2 MHz
• Bandwidth of chromancy signals (I and Q): 1.5 MHz and 0.5 MHz

Use by countries

Asian

• Burma
• South Korea
• Philippines
• Japan
• Taiwan

America

North America

• Bermuda
• Canada
• United States
• Mexico

Central America

South America

Caribbean Islands

Countries and territories that have stopped using NTSC

The following countries and regions no longer use NTSC for terrestrial broadcasts and are in the process of converting from NTSC (cable) to DVB-T, ATSC, or ISDB-T.

Country	Changed to	Completed switching
El SalvadorEl Salvador	ISDB-T	20222022
EcuadorEcuador		2026-03-01March 2026
Costa RicaCosta Rica		2023-01-31January 2023
ChileChile		2024-04-011 April 2024
Peru Peru		20282028
BermudaBermuda	DVB-T	2016-03-01March 2016
CanadaCanada	ATSC	2012-07-3131 August 2011 (selected markets)
JapanJapan	ISDB-T	2012-03-3131 March 2012
South KoreaSouth Korea	ATSC	2012-12-312012-03-3131 December 2012
Mexico Mexico		2015-12-312012-03-3131 December 2015 (High Power Stations)
Republic of China	DVB-T	2012-06-3030 June 2012
United States	ATSC	2009-06-1212 June 2009 (High Power Stations) 1 September 2015 (Class A Stations) 13 July 2021 (Lower Power Stations)