Engineering:PAL

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Short description: Colour encoding system for analogue television
Analog television encoding systems by nation; NTSC (green), SECAM (orange), and PAL (blue)

Phase Alternating Line (PAL) is a colour encoding system for analogue television. It was one of three major analogue colour television standards, the others being NTSC and SECAM. In most countries it was broadcast at 625 lines, 50 fields (25 frames) per second, and associated with CCIR analogue broadcast television systems B, D, G, H, I or K. The articles on analog broadcast television systems further describe frame rates, image resolution, and audio modulation.

PAL video is composite video because luminance (luma, monochrome image) and chrominance (chroma, colour applied to the monochrome image) are transmitted together as one signal.

A latter evolution of the standard, PALplus, added support for widescreen broadcasts with no loss of vertical resolution, while retaining compatibility with existing sets. Almost all of the countries using PAL are currently in the process of conversion, or have already converted transmission standards to DVB, ISDB or DTMB.

Geographic reach

PAL was adopted by most European countries, by several African countries, by Argentina , Brazil , Paraguay, Uruguay, and by most of Asia Pacific (including the Middle East).[1] Countries in those regions that did not adopt PAL were France ,[2] Francophone Africa,[2] several ex-Soviet states,[2] Japan ,[3] South Korea , Liberia, Myanmar, the Philippines ,[3] and Taiwan.[3]

PAL region

With the introduction of home video releases and later digital sources (e.g. DVD-Video), the name "PAL" might be used to refer to digital formats, even though they use completely different colour encoding systems. For example, 576i (576 interlaced lines) digital video with colour encoded as YCbCr, intended to be backward compatible and easily displayed on legacy PAL devices, is usually mentioned as "PAL" (ex: "PAL DVD"). Likewise, video game consoles outputting a 50 Hz signal might be labeled as "PAL", as opposed to 60 Hz on NTSC machines. These designations should not be confused with the analog colour system itself.

History

In the 1950s, the Western European countries began plans to introduce colour television, and were faced with the problem that the NTSC standard demonstrated several weaknesses, including colour tone shifting under poor transmission conditions, which became a major issue considering Europe's geographical and weather-related particularities. To overcome NTSC's shortcomings, alternative standards were devised, resulting in the development of the PAL and SECAM standards. The goal was to provide a colour TV standard for the European picture frequency of 50 fields per second (50 hertz), and finding a way to eliminate the problems with NTSC.

PAL was developed by Walter Bruch at Telefunken in Hanover, West Germany, with important input from Gerhard Mahler [de].[4] The format was patented by Telefunken in December 1962, citing Bruch as inventor,[5][6] and unveiled to members of the European Broadcasting Union (EBU) on 3 January 1963.[6] When asked why the system was named "PAL" and not "Bruch" the inventor answered that a "Bruch system" would probably not have sold very well ("Bruch" is the German word for "breakage"[7]).

The first broadcasts began in the United Kingdom in July 1967, followed by West Germany at the Berlin IFA on August 25.[6][8] The BBC channel initially using the broadcast standard was BBC2, which had been the first UK TV service to introduce "625-lines" during 1964. The Netherlands and Switzerland started PAL broadcasts by 1968, with Austria following the next year.[6]

Telefunken PALcolour 708T[9] was the first PAL commercial TV set. It was followed by Loewe-Farbfernseher S 920 and F 900.[10]

Telefunken was later bought by the French electronics manufacturer Thomson. Thomson also bought the Compagnie Générale de Télévision where Henri de France developed SECAM, the first European Standard for colour television. Thomson, now called Technicolour SA, also owns the RCA brand and licences it to other companies; Radio Corporation of America, the originator of that brand, created the NTSC colour TV standard before Thomson became involved.

The Soviets developed two further systems, mixing concepts from PAL and SECAM, known as TRIPAL and NIIR, that never went beyond tests.[6]

In 1993,[11] an evolution of PAL aimed to improve and enhance format by allowing 16:9 aspect ratio broadcasts, while remaining compatible with existing television receivers,[12] was introduced. Named PALplus, it was defined by ITU recommendation BT.1197-1. It was developed at the University of Dortmund in Germany , in cooperation with German terrestrial broadcasters and European and Japanese manufacturers. Adoption was limited to European countries.

With the introduction of digital broadcasts and signal sources (ex: DVDs, game consoles), the term PAL was used imprecisely to refer to the 625-line/50 Hz television system in general, to differentiate from the 525-line/60 Hz system generally used with NTSC. For example, DVDs were labelled as PAL or NTSC (referring to the line count and frame rate)[13] even though technically the discs carry neither PAL nor NTSC encoded signal. These devices would still have analog outputs (ex; composite video output), and would convert the digital signals (576i or 480i) to the analog standards to assure compatibility. CCIR 625/50 and EIA 525/60 are the proper names for these (line count and field rate) standards; PAL and NTSC on the other hand are methods of encoding colour information in the signal.

Color decoding methods

"PAL-D", "PAL-N", "PAL-H" and "PAL-K" designations on this section describe PAL decoding methods and are unrelated to broadcast systems with similar names.[6]

The Telefunken licence covered any decoding method that relied on the alternating subcarrier phase to reduce phase errors, described as "PAL-D" for "delay", and "PAL-N" for "new" or "Chrominance Lock".[6]

This excluded very basic PAL decoders that relied on the human eye to average out the odd/even line phase errors, and in the early 1970s some Japanese set manufacturers developed basic decoding systems to avoid paying royalties to Telefunken. These variations are known as "PAL-S" (for "simple" or "Volks-PAL"),[14] operating without a delay line and suffering from the “Hannover bars” effect. An example of this solution is the Kuba Porta Color CK211P set.[6] Another solution was to use a 1H analogue delay line to allow decoding of only the odd or even lines. For example, the chrominance on odd lines would be switched directly through to the decoder and also be stored in the delay line. Then, on even lines, the stored odd line would be decoded again. This method (known as 'gated NTSC') was adopted by Sony on their 1970s Trinitron sets (KV-1300UB to KV-1330UB), and came in two versions: "PAL-H" and "PAL-K" (averaging over multiple lines).[6][14] It effectively treated PAL as NTSC, suffering from hue errors and other problems inherent in NTSC and required the addition of a manual hue control.

Colour encoding

Un-decoded PAL image, showing chroma information as fine patterns chroma dots (click to zoom) overlapping the luma signal
Decoded PAL image, with chroma fully recovered. Some minor artifacts (see dot crawl) are present across transition areas (click to zoom)

Most PAL systems encode the colour information using a variant of the Y'UV colour space. [math]\displaystyle{ Y' }[/math]comprises the monochrome luma signal, with the three RGB colour channels mixed down onto two, [math]\displaystyle{ U }[/math] and [math]\displaystyle{ V }[/math].

Like NTSC, PAL uses a quadrature amplitude modulated subcarrier carrying the chrominance information added to the luma video signal to form a composite video baseband signal. The frequency of this subcarrier is 4.43361875 MHz for PAL 4.43, compared to 3.579545 MHz for NTSC 3.58. The SECAM system, on the other hand, uses a frequency modulation scheme on its two line alternate colour subcarriers 4.25000 and 4.40625 MHz.

The name "Phase Alternating Line" describes the way that the phase of part of the colour information on the video signal is reversed with each line, which automatically corrects phase errors in the transmission of the signal by cancelling them out, at the expense of vertical frame colour resolution. Lines where the colour phase is reversed compared to NTSC are often called PAL or phase-alternation lines, which justifies one of the expansions of the acronym, while the other lines are called NTSC lines. Early PAL receivers relied on the human eye to do that cancelling; however, this resulted in a comb-like effect known as Hanover bars on larger phase errors. Thus, most receivers now use a chrominance analogue delay line, which stores the received colour information on each line of display; an average of the colour information from the previous line and the current line is then used to drive the picture tube. The effect is that phase errors result in saturation changes, which are less objectionable than the equivalent hue changes of NTSC. A minor drawback is that the vertical colour resolution is poorer than the NTSC system's, but since the human eye also has a colour resolution that is much lower than its brightness resolution, this effect is not visible. In any case, NTSC, PAL, and SECAM all have chrominance bandwidth (horizontal colour detail) reduced greatly compared to the luma signal.

Spectrum of a System I television channel with PAL.
RF spectrogram and waterfall of an actual PAL-I transmission with NICAM.
Oscillogram of composite PAL signal—one frame.
Oscillogram of composite PAL signal—several lines.
Oscillogram of composite PAL signal—two lines.
A waterfall display showing a 20ms long interlaced PAL frame with high FFT resolution
Analyzing a PAL signal and decoding the 20ms frame and 64µs lines

The 4.43361875 MHz frequency of the colour carrier is a result of 283.75 colour clock cycles per line plus a 25 Hz offset to avoid interferences. Since the line frequency (number of lines per second) is 15625 Hz (625 lines × 50 Hz ÷ 2), the colour carrier frequency calculates as follows: 4.43361875 MHz = 283.75 × 15625 Hz + 25 Hz. The frequency 50 Hz is the optional refresh frequency of the monitor to be able to create an illusion of motion, while 625 lines means the vertical lines or resolution that the PAL system supports. The original colour carrier is required by the colour decoder to recreate the colour difference signals. Since the carrier is not transmitted with the video information it has to be generated locally in the receiver. In order that the phase of this locally generated signal can match the transmitted information, a 10 cycle burst of colour subcarrier is added to the video signal shortly after the line sync pulse, but before the picture information, during the so-called back porch. This colour burst is not actually in phase with the original colour subcarrier, but leads it by 45 degrees on the odd lines and lags it by 45 degrees on the even lines. This swinging burst enables the colour decoder circuitry to distinguish the phase of the [math]\displaystyle{ R-Y' }[/math]vector which reverses every line.

PAL signal details

For PAL-B/G the signal has these characteristics.

Parameter Value
Bandwidth 5 MHz[15]
Horizontal sync polarity Negative
Total time for each line 64 μs[16][17]
Front porch (A) 1.65+0.4
−0.1 μs
Sync pulse length (B) 4.7±0.20 μs
Back porch (C) 5.7±0.20 μs
Active video (D) 51.95+0.4
−0.1 μs

(Total horizontal sync time 12.05 µs)

After 0.9 µs a 2.25±0.23 μs colourburst of 10±1 cycles is sent. Most rise/fall times are in 250±50 ns range. Amplitude is 100% for white level, 30% for black, and 0% for sync.[16] The CVBS electrical amplitude is Vpp 1.0 V and impedance of 75 Ω.[18]

The composite video (CVBS) signal used in systems M and N before combination with a sound carrier and modulation onto an RF carrier.

The vertical timings are:

Parameter Value
Vertical lines 312.5 (625 total)
Vertical lines visible 288 (576 total)
Vertical sync polarity Negative (burst)
Vertical frequency 50 Hz
Sync pulse length (F) 0.576 ms (burst)[19]
Active video (H) 18.4 ms

(Total vertical sync time 1.6 ms)

As PAL is interlaced, every two fields are summed to make a complete picture frame.

Colorimetry

PAL colorimetry, as defined by the ITU on REC-BT.470, and based on CIE 1931 x,y coordinates:[20]

PAL colorimetry
Standard Year White point Primaries Display gamma EOTF
Red Green Blue
xʀ yʀ xɢ yɢ xʙ yʙ
PAL EBU 3213-E, ITU-R BT.470/601 (B/G) 1970 D65 0.64 0.33 0.29 0.60 0.15 0.06 2.8
PAL-M BT.470-6[21] 1972 C 0.67 0.33 0.21 0.71 0.14 0.08 2.2

The assumed display gamma is defined as 2.8.[20] The PAL-M system uses color primary and gamma values similar to NTSC.[21] Color is encoded using the YUV color space (with the exception of PAL-N, that uses YDbDr).

Luma ([math]\displaystyle{ E'{\scriptstyle\text{Y}} }[/math]) is derived from red, green, and blue ([math]\displaystyle{ E'{\scriptstyle\text{R}}, E'{\scriptstyle\text{G}}, E'{\scriptstyle\text{B}} }[/math]) gamma pre-corrected ([math]\displaystyle{ E' }[/math]) primary signals:[17]

  • [math]\displaystyle{ E'{\scriptstyle\text{Y}}= 0.299E'{\scriptstyle\text{R}} + 0.587E'{\scriptstyle\text{G}} + 0.114E'{\scriptstyle\text{B}} }[/math]

[math]\displaystyle{ E'{\scriptstyle\text{U}} }[/math] and [math]\displaystyle{ E'{\scriptstyle\text{V}} }[/math] are used to transmit chrominance. Each has a typical bandwidth of 1.3 MHz.

  • [math]\displaystyle{ E'{\scriptstyle\text{U}} = 0.492(E'{\scriptstyle\text{B}}-E'{\scriptstyle\text{Y}}) }[/math]
  • [math]\displaystyle{ E'{\scriptstyle\text{V}} = 0.877(E'{\scriptstyle\text{R}}-E'{\scriptstyle\text{Y}}) }[/math]

Composite PAL signal [math]\displaystyle{ = E'{\scriptstyle\text{Y}} + E'{\scriptstyle\text{U}} \sin (\omega t) + E'{\scriptstyle\text{V}} \cos (\omega t) + }[/math]timing[17] where [math]\displaystyle{ \omega = 2\pi F_{SC} }[/math].

Subcarrier frequency [math]\displaystyle{ F_{SC} }[/math] is 4.43361875 MHz (±5 Hz) for PAL-B/D/G/H/I/N.

PAL broadcast systems

The PAL colour system is usually used with a video format that has 625 lines per frame (576 visible lines, the rest being used for other information such as sync data and captioning) and a refresh rate of 50 interlaced fields per second (compatible with 25 full frames per second), such systems being B, G, H, I, and N (see broadcast television systems for the technical details of each format).

This ensures video interoperability. However, as some of these standards (B/G/H, I and D/K) use different sound carriers (5.5 MHz, 6.0 MHz and 6.5 MHz respectively), it may result in a video image without audio when viewing a signal broadcast over the air or cable. Some countries in Eastern Europe which formerly used SECAM with systems D and K have switched to PAL while leaving other aspects of their video system the same, resulting in the different sound carrier. Instead, other European countries have changed completely from SECAM-D/K to PAL-B/G.[22]

The PAL-N system has a different sound carrier, and also a different colour subcarrier, and decoding on incompatible PAL systems results in a black-and-white image without sound. The PAL-M system has a different sound carrier and a different colour subcarrier, and does not use 625 lines or 50 frames/second. This would result in no video or audio at all when viewing a European signal.

Differences between PAL variants[20]
PAL B PAL G, H PAL I PAL D/K, L PAL N PAL M
Transmission band VHF UHF VHF/UHF
Fields 50 60
Scan lines 625 525
Active lines 576 480
Channel bandwidth 7 MHz 8 MHz 6 MHz
Video bandwidth 5.0 MHz 5.5 MHz 6.0 MHz 4.2 MHz
Vision/Sound carrier spacing 5.5 MHz 6.0 MHz 6.5 MHz 4.5 MHz
Colour Subcarrier 4.43361875 MHz 3.58205625 MHz 3.575611 MHz
Assumed Receiver
Gamma correction 		2.8 2.2
Color model YUV YDbDr YUV

System A

The BBC tested their pre-war (but still broadcast until 1985) 405-line monochrome system (CCIR System A) with all three colour standards including PAL, before the decision was made to abandon 405 and transmit colour on 625/System I only.

PAL-B/G/D/K/I

Many countries have turned off analogue transmissions, so the following does not apply anymore, except for using devices which output RF signals, such as video recorders.

The majority of countries using or having used PAL have television standards with 625 lines and 50 fields per second. Differences concern the audio carrier frequency and channel bandwidths. The variants are:

  • Standards B/G are used in most of Western Europe, former Yugoslavia, South Asia, Australia, and New Zealand
  • Standard I in the UK, Ireland, Hong Kong, South Africa, and Macau
  • Standards D/K (along with SECAM usually) in most of Central and Eastern Europe and mainland China. Most analogue CCTV cameras are Standard D.[citation needed]

Systems B and G are similar. System B specifies 7 MHz channel bandwidth, while System G specifies 8 MHz channel bandwidth. Australia and China used Systems B and D respectively for VHF and UHF channels. Similarly, Systems D and K are similar except for the bands they use: System D is only used on VHF, while System K is only used on UHF. Although System I is used on both bands, it has only been used on UHF in the United Kingdom.

PAL-L

The PAL-L (Phase Alternating Line with CCIR System L broadcast system) standard uses the same video system as PAL-B/G/H (625 lines, 50 Hz field rate, 15.625 kHz line rate), but with a larger 6 MHz video bandwidth rather than 5.5 MHz and moving the audio subcarrier to 6.5 MHz. An 8 MHz channel spacing is used for PAL-L, to maintain compatibility with System L channel spacings.

PAL-N (Argentina, Paraguay and Uruguay)

In Argentina, Paraguay and Uruguay the PAL-N variant is used (Phase Alternating Line with CCIR System N broadcast system). It employs the 625 line/50 field per second waveform of PAL-B/G, D/K, H, and I, but on a 6 MHz channel with a chrominance subcarrier frequency of 3.582056 MHz (917/4*H) very similar to NTSC (910/4*H). PAL-N uses the YDbDr colour space.[20]

Extended features of the PAL specification, such as Teletext, are implemented quite differently in PAL-N. PAL-N supports a modified 608 closed captioning format that is designed to ease compatibility with NTSC originated NABTS content carried on line 18, and a modified teletext format that can occupy several lines.

PAL-M (Brazil)

Main page: PAL-M

In Brazil, PAL is used in conjunction with the 525 line, 60 field/s CCIR System M, using (very nearly) the NTSC colour subcarrier frequency. Exact colour subcarrier frequency of PAL-M is 3.575611 MHz, or 227.25 times System M's horizontal scan frequency. Almost all other countries using system M use NTSC.

The PAL colour system (either baseband or with any RF system, with the normal 4.43 MHz subcarrier unlike PAL-M) can also be applied to an NTSC-like 525-line picture to form what is often known as "PAL 60" (sometimes "PAL 60/525", "Quasi-PAL" or "Pseudo PAL"). PAL-M (a broadcast standard) however should not be confused with "PAL 60" (a video playback system—see below).

Home devices

Multisystem TVs

PAL television receivers manufactured in the 2000s can typically decode all of the PAL variants except, in some cases PAL-M and PAL-N. Many of receivers can also receive Eastern European and Middle Eastern SECAM, though rarely French-broadcast SECAM (because France used a quasi-unique positive video modulation, system L) unless they are manufactured for the French market. They will correctly display plain (non-broadcast) CVBS or S-video SECAM signals. Many can also accept baseband NTSC-M, such as from a VCR or game console, and RF modulated NTSC with a PAL standard audio subcarrier (i.e., from a modulator), though not usually broadcast NTSC (as its 4.5 MHz audio subcarrier is not supported). Many sets also support NTSC with a 4.43 MHz color subcarrier (see PAL 60 on the next section).

VHS and DVD players

VHS tapes recorded from a PAL-N or a PAL-B/G, D/K, H, or I broadcast are indistinguishable because the downconverted subcarrier on the tape is the same. A VHS recorded off TV (or released) in Europe will play in colour on any PAL-N VCR and PAL-N TV in Argentina, Paraguay and Uruguay. Likewise, any tape recorded in Argentina, Paraguay or Uruguay off a PAL-N TV broadcast can be sent to anyone in European countries that use PAL (and Australia/New Zealand, etc.) and it will display in colour. This will also play back successfully in Russia and other SECAM countries, as the USSR mandated PAL compatibility in 1985—this has proved to be very convenient for video collectors.

People in Argentina, Paraguay and Uruguay usually own TV sets that also display NTSC-M, in addition to PAL-N. DirecTV also conveniently broadcasts in NTSC-M for North, Central, and South America. Most DVD players sold in Argentina, Paraguay and Uruguay also play PAL discs—however, this is usually output in the European variant (colour subcarrier frequency 4.433618 MHz), so people who own a TV set which only works in PAL-N (plus NTSC-M in most cases) will have to watch those PAL DVD imports in black and white (unless the TV supports RGB SCART) as the colour subcarrier frequency in the TV set is the PAL-N variation, 3.582056 MHz.

In the case that a VHS or DVD player works in PAL (and not in PAL-N) and the TV set works in PAL-N (and not in PAL), there are two options:

  • images can be seen in black and white, or
  • an inexpensive transcoder (PAL -> PAL-N) can be purchased in order to see the colours

Some DVD players (usually lesser known brands) include an internal transcoder and the signal can be output in NTSC-M, with some video quality loss due to the standard conversion from a 625/50 PAL DVD to the NTSC-M 525/60 output format. A few DVD players sold in Argentina, Paraguay and Uruguay also allow a signal output of NTSC-M, PAL, or PAL-N. In that case, a PAL disc (imported from Europe) can be played back on a PAL-N TV because there are no field/line conversions, quality is generally excellent.

Some special VHS video recorders are available which can allow viewers the flexibility of enjoying PAL-N recordings using a standard PAL ( 625/50 Hz ) colour TV, or even through multi-system TV sets. Video recorders like Panasonic NV-W1E (AG-W1 for the US), AG-W2, AG-W3, NV-J700AM, Aiwa HV-M110S, HV-M1U, Samsung SV-4000W and SV-7000W feature a digital TV system conversion circuitry.

PAL 60

Many 1990s-onwards videocassette recorders sold in Europe can play back NTSC tapes. When operating in this mode most of them do not output a true (625/25) PAL signal, but rather a hybrid consisting of the original NTSC line standard (525/30), with colour converted to PAL 4.43 MHz (instead of 3.58 as with NTSC and South American PAL variants and with the PAL-specific phase alternation of colour difference signal between the lines) — this is known as "PAL 60" (also "quasi-PAL" or "pseudo-PAL") with "60" standing for 60 Hz (for 525/30), instead of 50 Hz (for 625/25).

Some video game consoles also output a signal in this mode. The Dreamcast pioneered PAL 60 with most of its games being able to play games at full speed like NTSC and without borders. Xbox and GameCube also support PAL 60 unlike PlayStation 2.[23] The PlayStation 2 did not actually offer a true PAL 60 mode; while many PlayStation 2 games did offer a "PAL 60" mode as an option, the console would in fact generate an NTSC signal during 60 Hz operation.

Most newer television sets can display a "PAL 60" signal correctly, but some will only do so (if at all) in black and white and/or with flickering/foldover at the bottom of the picture, or picture rolling (however, many old TV sets can display the picture properly by means of adjusting the V-Hold and V-Height knobs—assuming they have them). Some TV tuner cards or video capture cards will support this mode (although software/driver modification can be required and the manufacturers' specs may be unclear).

Some DVD players offer a choice of PAL vs NTSC output for NTSC discs.[24]

PAL vs. NTSC

PAL usually has 576 visible lines compared with 480 lines with NTSC, meaning that PAL has a 20% higher resolution, in fact it even has a higher resolution than Enhanced Definition standard (852x480). Most TV output for PAL and NTSC use interlaced frames meaning that even lines update on one field and odd lines update on the next field. Interlacing frames gives a smoother motion with half the frame rate. NTSC is used with a frame rate of 60i or 30p whereas PAL generally uses 50i or 25p; both use a high enough frame rate to give the illusion of fluid motion. This is due to the fact that NTSC is generally used in countries with a utility frequency of 60 Hz and PAL in countries with 50 Hz, although there are many exceptions.

Both PAL and NTSC have a higher frame rate than film which uses 24 frames per second. PAL has a closer frame rate to that of film, so most films are sped up 4% to play on PAL systems, shortening the runtime of the film and, without adjustment, slightly raising the pitch of the audio track. Film conversions for NTSC instead use 3:2 pull down to spread the 24 frames of film across 60 interlaced fields. This maintains the runtime of the film and preserves the original audio, but may cause worse interlacing artefacts during fast motion.

NTSC receivers have a tint control to perform colour correction manually. If this is not adjusted correctly, the colours may be faulty. The PAL standard automatically cancels hue errors by phase reversal, so a tint control is unnecessary yet Saturation control can be more useful. Chrominance phase errors in the PAL system are cancelled out using a 1H delay line resulting in lower saturation, which is much less noticeable to the eye than NTSC hue errors.

However, the alternation of colour information—Hanover bars—can lead to picture grain on pictures with extreme phase errors even in PAL systems, if decoder circuits are misaligned or use the simplified decoders of early designs (typically to overcome royalty restrictions). This effect will usually be observed when the transmission path is poor, typically in built up areas or where the terrain is unfavourable. The effect is more noticeable on UHF than VHF signals as VHF signals tend to be more robust. In most cases such extreme phase shifts do not occur.

PAL and NTSC have slightly divergent colour spaces, but the colour decoder differences here are ignored.


Outside of film and TV broadcasts, the differences between the two formats in video games are quite dramatic. To avoid timing problems or unfeasible code changes, games were historically slowed down by approximately 16.7%. This led to games ported over to PAL regions being known for inferior speed and frame rates compared to their NTSC counterparts. In addition, the increased resolution of PAL was often not utilised at all during conversion, creating a pseudo-letterbox effect with borders from the top to bottom. This was prevalent in previous generations, especially during the 8-bit and 16-bit era of games where 2D graphics were common at that time.

The Dreamcast offered a true "PAL 60" mode and games made for the system in PAL regions offered no significant differences compared to their NTSC counterparts in terms of speed and frame rates. The Xbox and GameCube also featured "PAL 60" modes in games made for the region as well. The lone exception was the PlayStation 2, where games ported over to PAL regions still run slower with borders compared to their NTSC counterparts. The PlayStation 2's lack of PAL 60 support was considered inexcusable by many users at the time due to the availability of TV sets supporting a 60 Hz scan rate with PAL colour (see "PAL 60" above) and RGB or component connections that allowed colour outputs without the need for NTSC or PAL colour encoding.

These problems associated with PAL region video games aren't necessarily encountered in Brazil with the PAL-M standard used in that region, as it uses an identical number of visible lines and refresh rate as NTSC but with a slightly different colour encoding frequency based on PAL, which was slightly modified for the System M colour encoding system.

PAL vs. SECAM

The SECAM patents predate those of PAL by several years (1956 vs. 1962). Its creator, Henri de France, in search of a response to known NTSC hue problems, came up with ideas that were to become fundamental to both European systems, namely:

  1. colour information on two successive TV lines is very similar and vertical resolution can be halved without serious impact on perceived visual quality
  2. more robust colour transmission can be achieved by spreading information on two TV lines instead of just one
  3. information from the two TV lines can be recombined using a delay line.

SECAM applies those principles by transmitting alternately only one of the U and V components on each TV line, and getting the other from the delay line. QAM is not required, and frequency modulation of the subcarrier is used instead for additional robustness (sequential transmission of U and V was to be reused much later in Europe's last "analog" video systems: the MAC standards).

SECAM is free of both hue and saturation errors. It is not sensitive to phase shifts between the colour burst and the chrominance signal, and for this reason was sometimes used in early attempts at colour video recording, where tape speed fluctuations could get the other systems into trouble. In the receiver, it did not require a quartz crystal (which was an expensive component at the time) and generally could do with lower accuracy delay lines and components.

SECAM transmissions are more robust over longer distances than NTSC or PAL. However, owing to their FM nature, the colour signal remains present, although at reduced amplitude, even in monochrome portions of the image, thus being subject to stronger cross colour.

One serious drawback for studio work is that the addition of two SECAM signals does not yield valid colour information, due to its use of frequency modulation. It was necessary to demodulate the FM and handle it as AM for proper mixing, before finally remodulating as FM, at the cost of some added complexity and signal degradation. In its later years, this was no longer a problem, due to the wider use of component and digital equipment.

PAL can work without a delay line (PAL-S), but this configuration, sometimes referred to as "poor man's PAL", could not match SECAM in terms of picture quality. To compete with it at the same level, it had to make use of the main ideas outlined above, and as a consequence PAL had to pay licence fees to SECAM. Over the years, this contributed significantly to the estimated 500 million francs gathered by the SECAM patents (for an initial 100 million francs invested in research).[25]

Hence, PAL could be considered as a hybrid system, with its signal structure closer to NTSC, but its decoding borrowing much from SECAM.

There were initial specifications to use colour with the French 819 line format (system E). However, "SECAM E" only ever existed in development phases. Actual deployment used the 625 line format. This made for easy interchange and conversion between PAL and SECAM in Europe. Conversion was often not even needed, as more and more receivers and VCRs became compliant with both standards, helped in this by the common decoding steps and components. When the SCART plug became standard, it could take RGB as an input, effectively bypassing all the colour coding formats' peculiarities.

When it comes to home VCRs, all video standards use what is called "colour under" format. Colour is extracted from the high frequencies of the video spectrum, and moved to the lower part of the spectrum available from tape. Luma then uses what remains of it, above the colour frequency range. This is usually done by heterodyning for PAL (as well as NTSC). But the FM nature of colour in SECAM allows for a cheaper trick: division by 4 of the subcarrier frequency (and multiplication on replay). This became the standard for SECAM VHS recording in France. Most other countries kept using the same heterodyning process as for PAL or NTSC and this is known as MESECAM recording (as it was more convenient for some Middle East countries that used both PAL and SECAM broadcasts). Another difference in colour management is related to the proximity of successive tracks on the tape, which is a cause for chroma crosstalk in PAL. A cyclic sequence of 90° chroma phase shifts from one line to the next is used to overcome this problem. This is not needed in SECAM, as FM provides sufficient protection.

Regarding early (analogue) videodiscs, the established Laserdisc standard supported only NTSC and PAL. However, a different optical disc format, the Thomson transmissive optical disc made a brief appearance on the market. At some point, it used a modified SECAM signal (single FM subcarrier at 3.6 MHz[26]). The media's flexible and transmissive material allowed for direct access to both sides without flipping the disc, a concept that reappeared in multi-layered DVDs about fifteen years later.

Countries and territories that are using or once used PAL

Below are lists of countries and territories that used or once used the PAL system. Many of these have converted or are converting PAL to DVB-T (most countries), DVB-T2 (most countries), DTMB (China, Hong Kong and Macau) or ISDB (Sri Lanka, Maldives, Botswana, Brazil, Argentina, Paraguay and Uruguay).

A legacy list of PAL users in 1998 is available on Recommendation ITU-R BT.470-6 - Conventional Television Systems, Appendix 1 To Annex 1.[27]

Using PAL B, D, G, H, K or I

  •  Afghanistan (used SECAM)[28]
  •  Algeria
  •  Angola[28]
  •  Armenia
  •  Bahrain (DVB-T introduction in assessment)[28]
  •  Bangladesh[28]
  •  Bhutan[28]
  •  Bosnia and Herzegovina[28]
  •  Botswana[28]
  • Template:IOT[28]
  •  Cameroon[28]
  •  Cape Verde[28]
  •  Christmas Island
  •  Comoros
  •  Cook Islands (see New Zealand)
  •  Djibouti[28]
  •  Egypt (migrated from SECAM 1990–1992)[28]
  •  Equatorial Guinea[28]
  •  Eritrea[28]
  •  Eswatini[28]
  •  Ethiopia[28]
  •  Falkland Islands (UHF only)[28]
  •  Fiji
  •  Gambia[28]
  •  Guinea-Bissau[28]
  •  Iraq[28](DVB-T introduction in assessment)
  •  Jordan[29] (DVB-T introduction in assessment)
  •  Kiribati[28]
  •  Kuwait[28]
  •  Laos (Once experimented in PAL-M)[28]
  •  Lebanon (uses PAL for Lebanese channels)
  •  Lesotho[28]
  •  Liberia[28]
  •  Libya
  • Template:MAW[28]
  •  Maldives[28]
  •  Mauritius
  •  Moldova
  •  Mongolia
  •  Mozambique[28]
  •  Nauru[28]
  •    Nepal[28]
  •  Nigeria
  •  Niue[28]
  •  Norfolk Island (see Australia)
  •  North Korea (used SECAM until 1990s)[28]
  •  Oman (DVB-T introduction in assessment)[28]
  •  Pakistan[28]
  • Template:PLE (DVB-T introduction in assessment)
  •  Papua New Guinea[28]
  •  Saint Helena, Ascension and Tristan da Cunha (Two PAL-I analogue TV services operated by BFBS)
  • Template:SAM[28]
  •  São Tomé and Príncipe
  •  Seychelles[28]
  •  Sierra Leone[28]
  •  Solomon Islands
  •  Somalia[28]
  •  South Sudan
  •  Sri Lanka[28]
  •  Sudan[28]
  •  Syria (along with SECAM)[28]
  •  Timor-Leste
  • Template:TGA[28] (PAL broadcast to be abandoned. Analog shutoff scheduled for 15 June 2015. Simulcast in DVB-T)
  •  Turkey
  •  Tuvalu[28]
  •  Uganda[28]
  •  Vanuatu[28]
  •  Yemen[28] (DVB-T introduction)
  •  Zimbabwe[28]


PAL-M

  •  Brazil (H264 video over ISDB-T, at 480i@60 Hz (SD) or 1080i@60 Hz (HD), simulcast with digital format in ISDB-Tb, also called SBTVD), an update to ISDB-T, started in December 2007. PAL broadcasting in its final stages of abandonment, the complete shut-down is scheduled to 2023.

PAL-N

  •  Argentina (H264 video over ISDB-T, at 480i/576i@50/60 Hz (SD) or 1080i@50/60 Hz (HD), simulcast with digital format in ISDB-Tb, also called SBTVD), an update to ISDB-T, started in August 28, 2008. PAL broadcasting in its final stages of abandonment, the complete shut-down is scheduled to 2023.
  •  Paraguay (Simulcast in ISDB-T)
  •  Uruguay (Simulcast in ISDB-T)

Countries and territories that have ceased using PAL

The following countries and territories no longer use PAL for terrestrial broadcasts, and are in process of converting from PAL to DVB-T/T2, DTMB or ISDB-T.

Country Switched to Switchover completed
 Albania DVB-T2 2019-10-011 October 2019
 Andorra DVB-T 2007-09-2525 September 2007
 Australia DVB-T 2013-12-1010 December 2013
 Austria DVB-T and DVB-T2 2010-06-077 June 2011
 Azerbaijan DVB-T 2015-06-1717 June 2015
 Belgium DVB-T 2010-03-011 March 2010
 Brunei DVB-T 2015-01-011 January 2015
 Bulgaria DVB-T 2013-09-3030 September 2013
 Cambodia DVB-T2 2015-01-011 January 2015
 China DTMB 2021-03-3131 March 2021
 Croatia DVB-T2 12 November 2020[30]
 Cyprus DVB-T 2011-07-011 July 2011
 Czech Republic DVB-T and DVB-T2 2012-06-3030 June 2012
 Denmark DVB-T and DVB-T2 2009-11-011 November 2009
 Estonia DVB-T 2010-07-011 July 2010
 Faroe Islands DVB-T 2002–12 December 2002
 Finland DVB-T and DVB-T2 2007-09-011 September 2007
 Georgia DVB-T 2015-07-011 July 2015
 Germany DVB-T and DVB-T2 2009-06-044 June 2009
 Ghana DVB-T2 2015-06June 2015
 Greece DVB-T 2015-02-056 February 2015
 Gibraltar DVB-T 2012-12-3131 December 2012
 Guernsey DVB-T 2010-11-1717 November 2010
 Hong Kong DTMB 2020-12-011 December 2020
 Hungary DVB-T and DVB-T2 2013-10-3131 October 2013
 Iceland DVB-T and DVB-T2 2015-02-022 February 2015
 India DVB-T 2015-03-3131 March 2015
 Indonesia DVB-T2 2023-08-1212 August 2023[31]
 Iran DVB-T 2014-12-1919 December 2014
 Ireland DVB-T 2012-10-2424 October 2012
 Isle of Man DVB-T 2012-10-2424 October 2012
 Israel DVB-T and DVB-T2 2011-06-1313 June 2011
 Italy DVB-T 2012-07-044 July 2012
 Jersey DVB-T 2010-11-1717 November 2010
 Kenya DVB-T 2015-03March 2015
 Latvia DVB-T 2010-06-011 June 2010
 Lithuania DVB-T 2012-10-2929 October 2012
 Luxembourg DVB-T 2006-09-011 September 2006
 Macau DTMB 2023-06-3030 June 2023[32]
 North Macedonia DVB-T 2013-05-3131 May 2013
 Malaysia DVB-T2 2019-10-3131 October 2019
 Malta DVB-T 2011-10-3131 October 2011
 Monaco DVB-T 2011-05-2424 May 2011
 Montenegro DVB-T 2015-06-1717 June 2015
 Namibia DVB-T 2014-09-1313 September 2014
 Netherlands DVB-T 2006-12-1414 December 2006
 New Zealand DVB-T 2013-12-011 December 2013
 Norway DVB-T 2009-12December 2009[33]
 Poland DVB-T 2013-07-2323 July 2013
 Portugal DVB-T 2012-04-2626 April 2012
 Qatar DVB-T and DVB-T2 2012-02-1313 February 2012
 Romania DVB-T2 2016-12-3131 December 2016
 Rwanda DVB-T 2014-03March 2014
 San Marino DVB-T 2010-12-022 December 2010
 Saudi Arabia DVB-T and DVB-T2 2012-02-1313 February 2012
 Serbia DVB-T2 2015-06-077 June 2015
 Singapore DVB-T2 2019-01-022 January 2019
 Slovakia DVB-T 2012-12-3131 December 2012
 Slovenia DVB-T 2010-12-011 December 2010
 South Africa DVB-T 20152015[34] (as of 2018, PAL terrestrial still operational)
 Spain DVB-T and DVB-T2 2010-04-033 April 2010
 Sweden DVB-T and DVB-T2 2007-10-2929 October 2007
  Switzerland DVB-T 2007-11-2626 November 2007
 Tanzania DVB-T 2014-07July 2014
 Thailand DVB-T2 2020-0926 March 2020
 Ukraine DVB-T and DVB-T2 2016-12-3131 December 2016
 United Arab Emirates DVB-T and DVB-T2 2012-02-1313 February 2012
 United Kingdom DVB-T (SD) and DVB-T2 (HD) 2012-10-2424 October 2012
 Vietnam DVB-T2 2020-12-2828 December 2020
 Zambia DVB-T2 2014-12-3131 December 2014

See also

References

  1. ↑ "PGC categories – Countries using PAL standard". 22 April 2009. http://www.dvd-replica.com/DVD/palnations.php. 
  2. ↑ 2.0 2.1 2.2 "PGC categories – Countries using SECAM standard". 23 February 2009. http://dvd-replica.com/DVD/secamnations.php. 
  3. ↑ 3.0 3.1 3.2 "PGC categories – Countries using NTSC standard". 22 April 2009. http://dvd-replica.com/DVD/ntscnations.php. 
  4. ↑ "Walter Bruch and the PAL Color Television System". 2 March 2020. http://scihi.org/walter-bruch/. "In 1963, when he gave a public presentation of the Phase Alternation Line to a group of experts from the European Broadcasting Union in Hannover" 
  5. ↑ "Walter Bruch; PAL Television". 7 December 2019. https://www.radios-tv.co.uk/walter-bruch-pal-television/. "In 1950s, when Telefunken commissioned Bruch to invent an automated differential phase correction for color television. That's why he was awarded." 
  6. ↑ 6.0 6.1 6.2 6.3 6.4 6.5 6.6 6.7 6.8 "45 Years Anniversary of Walter Bruch's PAL Color Television". https://www.radiomuseum.org/forum/45_years_anniversary_of_walter_bruchs_pal_color_television.html. 
  7. ↑ "English translation of 'Bruch'". https://www.collinsdictionary.com/dictionary/german-english/bruch. 
  8. ↑ The standard that defines the PAL system was last published by the International Telecommunication Union in 1998 and has the title Recommendation ITU-R BT.470, Conventional Television Systems
  9. ↑ "Telefunken PALcolour 708 TV advert". https://www.radiomuseum.org/forumdata/users/4144/40_years_PAL/D_Telefunken_1967_708SM_advert.jpg. 
  10. ↑ "Loewe-Farbfernseher S 920 & F 900 PAL TV advert". https://buizenradioclub.nl/media/kunena/attachments/111/Loewe2_1967.jpg. 
  11. ↑ "EUR-Lex – 31993D0424 – EN". 5 August 1993. pp. 48–54. https://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=CELEX:31993D0424:EN:HTML. 
  12. ↑ "Fluke PM5420 Application Note PALplus". https://assets.fluke.com/appnotes/it_products/B0291A-16U9509_NL_EN.pdf. 
  13. ↑ "What Is a NTSC Format DVD? How Can I Play a NTSC DVD in the UK Without Restriction?". https://www.videoconverterfactory.com/tips/ntsc-format-dvd.html. 
  14. ↑ 14.0 14.1 "Tech Notes: Colour TV". 2007-07-16. https://www.camerasunderwater.info/engineering/tv_stds/colortv.html. 
  15. ↑ "PGC categories – Countries using PAL standard". http://www.dvd-replica.com/DVD/palnations.php.  090426 dvd-replica.com
  16. ↑ 16.0 16.1 "Horizontal Blanking Interval of 405-, 525-, 625- and 819-Line Standards". http://www.pembers.freeserve.co.uk/World-TV-Standards/HBI.pdf.  090426 pembers.freeserve.co.uk
  17. ↑ 17.0 17.1 17.2 "NTSC, PAL, and SECAM Overview". p. 52. http://www.deetc.isel.ipl.pt/Analisedesinai/sm/downloads/doc/ch08.pdf. 
  18. ↑ LDK 5400 Triax Adapter Technical Manual. Thomson Multimedia Broadcast Solutions. 2002. https://wwwapps.grassvalley.com/docs/Manuals/cameras/ldk5400/3922-496-46791.s03.v01.pdf. 
  19. ↑ "Vertical Blanking Interval of 625-Line Standard (PAL Colour)". http://www.pembers.freeserve.co.uk/World-TV-Standards/VBI-625-PAL.pdf. 
  20. ↑ 20.0 20.1 20.2 20.3 "RECOMMENDATION ITU-R BT.470-6 - CONVENTIONAL TELEVISION SYSTEMS". https://www.itu.int/dms_pubrec/itu-r/rec/bt/R-REC-BT.470-6-199811-S!!PDF-E.pdf. 
  21. ↑ 21.0 21.1 "RECOMMENDATION ITU-R BT.470-6 - CONVENTIONAL TELEVISION SYSTEMS, p.16". https://www.itu.int/dms_pubrec/itu-r/rec/bt/R-REC-BT.470-6-199811-S!!PDF-E.pdf#page=16. 
  22. ↑ "Changes to the terrestrial television systems in Central and East European countries". EBU. http://tech.ebu.ch/docs/i/i033.pdf. 
  23. ↑ "The Virtual Console's PAL Problem". 15 April 2010. https://www.nintendolife.com/news/2010/04/talking_point_the_virtual_consoles_pal_problem. 
  24. ↑ "Playback of NTSC Videos on PAL Equipment". https://www.amigaforever.com/kb/16-111. 
  25. ↑ "The CCIR, the standards and the TV sets' market in France" (section III.1)
  26. ↑ "Les Videodisques", Georges Broussaud (head/member of development team), editions Masson
  27. ↑ RECOMMENDATION ITU-R BT.470-6 - CONVENTIONAL TELEVISION SYSTEMS. ITU Radiocommunication Assembly. 1998. pp. 29–34. https://www.itu.int/dms_pubrec/itu-r/rec/bt/R-REC-BT.470-6-199811-S!!PDF-E.pdf. 
  28. ↑ 28.00 28.01 28.02 28.03 28.04 28.05 28.06 28.07 28.08 28.09 28.10 28.11 28.12 28.13 28.14 28.15 28.16 28.17 28.18 28.19 28.20 28.21 28.22 28.23 28.24 28.25 28.26 28.27 28.28 28.29 28.30 28.31 28.32 28.33 28.34 28.35 28.36 28.37 28.38 28.39 28.40 28.41 28.42 28.43 28.44 28.45 28.46 28.47 Michael Hegarty; Anne Phelan; Lisa Kilbride (1 January 1998). Classrooms for Distance Teaching and Learning: A Blueprint. Leuven University Press. pp. 260–. ISBN 978-90-6186-867-5. https://books.google.com/books?id=5YjHecPlPS8C&pg=PA260. 
  29. ↑ "PAL / NTSC / SECAM countries list". http://shop.sandbag.uk.com/OneGiantLeap/PALNTSCInfo.html. 
  30. ↑ "Prijelaz na DVB-T2 TV signal s HEVC (H.265) sažimanjem | OIV digitalni signali i mreže" (in hr). https://gledajbezbrige.oiv.hr/dvb-t2-prijelaz/. 
  31. ↑ "Siaran TV Analog Disetop di Seluruh RI 12 Agustus 2023". https://www.detik.com/jabar/berita/d-6870993/siaran-tv-analog-disetop-di-seluruh-ri-12-agustus-2023. 
  32. ↑ "TDM to switch off analogue television transmission system". https://www.tdm.com.mo/en/news-detail/850844. 
  33. ↑ "TV og radio". https://www.nkom.no/fritid/digital-radio/digitalt-bakkenett/digitalt-bakkenett-i-norge. 
  34. ↑ "Switching Off Analogue TV Will Lock Out Many In Africa". 14 August 2014. http://afkinsider.com/68611/analogue-tv-banning-to-switch-off-many-in-africa/. 

External links



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