Phase Alternating Line (PAL) is a colour encoding system for
analogue television
Analog television is the original television technology that uses analog signals to transmit video and audio. In an analog television broadcast, the brightness, colors and sound are represented by amplitude, phase and frequency of an analog s ...
. It was one of three major analogue colour television standards, the others being
NTSC
The first American standard for analog television broadcast was developed by National Television System Committee (NTSC)National Television System Committee (1951–1953), Report and Reports of Panel No. 11, 11-A, 12–19, with Some supplement ...
and
SECAM
SECAM, also written SÉCAM (, ''Séquentiel de couleur à mémoire'', French for ''color sequential with memory''), is an analog color television system that was used in France, some parts of Europe and Africa, and Russia. It was one of th ...
. In most countries it was broadcast at
625 lines 625-lines is a standard-definition television resolution used mainly in the context of analog systems. It was first demonstrated by Mark Iosifovich Krivosheev in 1948.
Analog broadcast television standards
The following International Telecommunic ...
, 50 fields (25 frames) per second, and associated with CCIR analogue
broadcast television systems
Broadcast television systems (or terrestrial television systems outside the US and Canada) are the encoding or formatting systems for the transmission and reception of terrestrial television signals.
Analog television systems were standardized by ...
B,
D,
G,
H,
I or
K. The articles on analog
broadcast television system
Broadcast television systems (or terrestrial television systems outside the US and Canada) are the encoding or formatting systems for the transmission and reception of terrestrial television signals.
Analog television systems were standardized by ...
s further describe
frame rate
Frame rate (expressed in or FPS) is the frequency (rate) at which consecutive images (frames) are captured or displayed. The term applies equally to film and video cameras, computer graphics, and motion capture systems. Frame rate may also be ca ...
s,
image resolution
Image resolution is the detail an image holds. The term applies to digital images, film images, and other types of images. "Higher resolution" means more image detail.
Image resolution can be measured in various ways. Resolution quantifies how ...
, and audio modulation.
PAL video is
composite video
Composite video is an analog video signal format that carries standard-definition video (typically at 525 lines or 625 lines) as a single channel. Video information is encoded on one channel, unlike the higher-quality S-Video (two channels) a ...
because
luminance
Luminance is a photometric measure of the luminous intensity per unit area of light travelling in a given direction. It describes the amount of light that passes through, is emitted from, or is reflected from a particular area, and falls withi ...
(luma, monochrome image) and
chrominance
Chrominance (''chroma'' or ''C'' for short) is the signal used in video systems to convey the color information of the picture (see YUV color model), separately from the accompanying luma signal (or Y' for short). Chrominance is usually represente ...
(chroma, colour applied to the monochrome image) are transmitted together as one signal.
A latter evolution of the standard,
PALplus
PALplus (or ''PAL+'') is an analogue television broadcasting system aimed to improve and enhance the PAL format by allowing 16:9 (or 1.77:1) aspect ratio broadcasts, while remaining compatible with existing television receivers, defined by ITU re ...
, added support for
widescreen
Widescreen images are displayed within a set of aspect ratios (relationship of image width to height) used in film, television and computer screens. In film, a widescreen film is any film image with a width-to-height aspect ratio greater than t ...
broadcasts with no loss of vertical
resolution
Resolution(s) may refer to:
Common meanings
* Resolution (debate), the statement which is debated in policy debate
* Resolution (law), a written motion adopted by a deliberative body
* New Year's resolution, a commitment that an individual mak ...
, 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
Digital Video Broadcasting (DVB) is a set of international open standards for digital television. DVB standards are maintained by the DVB Project, an international industry consortium, and are published by a Joint Technical Committee (JTC) o ...
,
ISDB
Integrated Services Digital Broadcasting (ISDB; Japanese language, Japanese: , ''Tōgō dejitaru hōsō sābisu'') is a Japanese broadcasting standard for digital television (DTV) and digital radio.
ISDB supersedes both the NTSC-J analog telev ...
or
DTMB
DTMB (Digital Terrestrial Multimedia Broadcast) is the digital TV standard for mobile and fixed devices, developed in the People's Republic of China. It is used there and in both of their special administrative regions (Hong Kong and Macau), and ...
.
Due to the introduction of digital sources (ex:
DVD-Video
DVD-Video is a consumer video format used to store digital video on DVD discs. DVD-Video was the dominant consumer home video format in Asia, North America, Europe, and Australia in the 2000s until it was supplanted by the high-definition Blu-r ...
) the name "PAL" might be used to refer to digital formats, even though they use completely different colour encoding systems. For example,
576i
576i is a standard-definition television, standard-definition digital video mode, originally used for digitizing analog television in most countries of the world where the utility frequency for electric power distribution is 50 Hz. Because ...
(576 interlaced lines) digital video with colour encoded as
YCbCr
YCbCr, Y′CbCr, or Y Pb/Cb Pr/Cr, also written as YCBCR or Y′CBCR, is a family of color spaces used as a part of the color image pipeline in video and digital photography systems. Y′ is the luma component and CB and CR are the blue-diffe ...
, intended to be backward compatible and easily displayed on legacy PAL devices, is usually mentioned as "PAL" (ex: "PAL DVD"). Likewise, gaming consoles outputting a 50 Hz signal might be labeled as "PAL", as opposed to 60 Hz "NTSC" machines. These popular designations should not be confused with the analog colour system itself.
Geographic reach
PAL was adopted by most European countries, by all African countries that had never been a
Belgian
Belgian may refer to:
* Something of, or related to, Belgium
* Belgians, people from Belgium or of Belgian descent
* Languages of Belgium, languages spoken in Belgium, such as Dutch, French, and German
*Ancient Belgian language, an extinct languag ...
or
French colony
The French colonial empire () comprised the overseas colonies, protectorates and mandate territories that came under French rule from the 16th century onward. A distinction is generally made between the "First French Colonial Empire", that existe ...
, by
Argentina
Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, th ...
,
Brazil
Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...
,
Paraguay
Paraguay (; ), officially the Republic of Paraguay ( es, República del Paraguay, links=no; gn, Tavakuairetã Paraguái, links=si), is a landlocked country in South America. It is bordered by Argentina to the south and southwest, Brazil to th ...
,
Uruguay
Uruguay (; ), officially the Oriental Republic of Uruguay ( es, República Oriental del Uruguay), is a country in South America. It shares borders with Argentina to its west and southwest and Brazil to its north and northeast; while bordering ...
, and by most of
Asia (including the Middle East) and the Pacific. Countries in those regions that did not adopt PAL were
France
France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of Overseas France, overseas regions and territories in the Americas and the Atlantic Ocean, Atlantic, Pacific Ocean, Pac ...
,
most ex-
Soviet
The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, ...
states,
Japan
Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...
,
South Korea
South Korea, officially the Republic of Korea (ROK), is a country in East Asia, constituting the southern part of the Korea, Korean Peninsula and sharing a Korean Demilitarized Zone, land border with North Korea. Its western border is formed ...
,
Liberia
Liberia (), officially the Republic of Liberia, is a country on the West African coast. It is bordered by Sierra Leone to Liberia–Sierra Leone border, its northwest, Guinea to its north, Ivory Coast to its east, and the Atlantic Ocean ...
,
Myanmar
Myanmar, ; UK pronunciations: US pronunciations incl. . Note: Wikipedia's IPA conventions require indicating /r/ even in British English although only some British English speakers pronounce r at the end of syllables. As John C. Wells, Joh ...
, the
Philippines
The Philippines (; fil, Pilipinas, links=no), officially the Republic of the Philippines ( fil, Republika ng Pilipinas, links=no),
* bik, Republika kan Filipinas
* ceb, Republika sa Pilipinas
* cbk, República de Filipinas
* hil, Republ ...
,
and
Taiwan
Taiwan, officially the Republic of China (ROC), is a country in East Asia, at the junction of the East and South China Seas in the northwestern Pacific Ocean, with the People's Republic of China (PRC) to the northwest, Japan to the nort ...
.
History
In the 1950s, the Western European countries began plans to introduce colour television, and were faced with the problem that the
NTSC
The first American standard for analog television broadcast was developed by National Television System Committee (NTSC)National Television System Committee (1951–1953), Report and Reports of Panel No. 11, 11-A, 12–19, with Some supplement ...
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
Fields may refer to:
Music
*Fields (band), an indie rock band formed in 2006
*Fields (progressive rock band), a progressive rock band formed in 1971
* ''Fields'' (album), an LP by Swedish-based indie rock band Junip (2010)
* "Fields", a song by ...
per second (50
hertz
The hertz (symbol: Hz) is the unit of frequency in the International System of Units (SI), equivalent to one event (or cycle) per second. The hertz is an SI derived unit whose expression in terms of SI base units is s−1, meaning that on ...
), and finding a way to eliminate the problems with NTSC.
PAL was developed by
Walter Bruch
Walter Bruch (2 March 1908 – 5 May 1990) was a German electrical engineer and pioneer of German television. He was the inventor of Closed-circuit television. He invented the PAL colour television system at Telefunken in the early 1960s. In add ...
at
Telefunken
Telefunken was a German radio and television apparatus company, founded in Berlin in 1903, as a joint venture of Siemens & Halske and the ''Allgemeine Elektrizitäts-Gesellschaft'' (AEG) ('General electricity company').
The name "Telefunken" app ...
in Hanover,
West Germany
West Germany is the colloquial term used to indicate the Federal Republic of Germany (FRG; german: Bundesrepublik Deutschland , BRD) between its formation on 23 May 1949 and the German reunification through the accession of East Germany on 3 O ...
, with important input from . The format was patented by
Telefunken
Telefunken was a German radio and television apparatus company, founded in Berlin in 1903, as a joint venture of Siemens & Halske and the ''Allgemeine Elektrizitäts-Gesellschaft'' (AEG) ('General electricity company').
The name "Telefunken" app ...
in December 1962, citing Bruch as inventor,
and unveiled to members of the
European Broadcasting Union
The European Broadcasting Union (EBU; french: Union européenne de radio-télévision, links=no, UER) is an alliance of Public broadcasting, public service media organisations whose countries are within the European Broadcasting Area or who ar ...
(EBU) on 3 January 1963.
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").
The first broadcasts began in the
United Kingdom
The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the continental mainland. It comprises England, Scotland, Wales and North ...
in July 1967, followed by
West Germany
West Germany is the colloquial term used to indicate the Federal Republic of Germany (FRG; german: Bundesrepublik Deutschland , BRD) between its formation on 23 May 1949 and the German reunification through the accession of East Germany on 3 O ...
at the
Berlin IFA on August 25
th.
[The standard that defines the PAL system was last published by the ]International Telecommunication Union
The International Telecommunication Union is a specialized agency of the United Nations responsible for many matters related to information and communication technologies. It was established on 17 May 1865 as the International Telegraph Unio ...
in 1998 and has the titl
''Recommendation ITU-R BT.470, Conventional Television Systems''
/ref> The BBC channel initially using the broadcast standard was BBC2
BBC Two is a British free-to-air public broadcast television network owned and operated by the BBC. It covers a wide range of subject matter, with a remit "to broadcast programmes of depth and substance" in contrast to the more mainstream an ...
, which had been the first UK TV service to introduce "625-lines" during 1964. The Netherlands
)
, anthem = ( en, "William of Nassau")
, image_map =
, map_caption =
, subdivision_type = Sovereign state
, subdivision_name = Kingdom of the Netherlands
, established_title = Before independence
, established_date = Spanish Netherl ...
and Switzerland
). Swiss law does not designate a ''capital'' as such, but the federal parliament and government are installed in Bern, while other federal institutions, such as the federal courts, are in other cities (Bellinzona, Lausanne, Luzern, Neuchâtel ...
started PAL broadcasts by 1968, with Austria
Austria, , bar, Östareich officially the Republic of Austria, is a country in the southern part of Central Europe, lying in the Eastern Alps. It is a federation of nine states, one of which is the capital, Vienna, the most populous ...
following the next year.
''Telefunken PALcolour 708T'' was the first PAL commercial TV set. It was followed by '' Loewe-Farbfernseher S 920'' and ''F 900''.
Telefunken was later bought by the French electronics manufacturer Thomson Thomson may refer to:
Names
* Thomson (surname), a list of people with this name and a description of its origin
* Thomson baronets, four baronetcies created for persons with the surname Thomson
Businesses and organizations
* SGS-Thomson Mic ...
. Thomson also bought the ''Compagnie Générale de Télévision'' where Henri de France
Henri Georges de France (7 September 1911 Paris – 29 April 1986 Paris) was a pioneering French television inventor. His inventions include the 819 line French standard and the SECAM color system. He was also apparently behind the HD-MAC high ...
developed SECAM, the first European Standard
European Standards (abbreviated EN, from the German name ("European Norm")) are technical standards which have been ratified by one of the three European standards organizations: European Committee for Standardization (CEN), European Committee for ...
for colour television. Thomson, now called Technicolour SA, also owns the RCA brand and licences it to other companies; Radio Corporation of America
The RCA Corporation was a major American electronics company, which was founded as the Radio Corporation of America in 1919. It was initially a patent trust owned by General Electric (GE), Westinghouse, AT&T Corporation and United Fruit Comp ...
, the originator of that brand, created the NTSC colour TV standard before Thomson became involved.
The soviets
Soviet people ( rus, сове́тский наро́д, r=sovyétsky naród), or citizens of the USSR ( rus, гра́ждане СССР, grázhdanye SSSR), was an umbrella demonym for the population of the Soviet Union.
Nationality policy in th ...
developed two further systems, mixing concepts from PAL and SECAM, known as TRIPAL and NIIR, that never went beyond tests.
In the early 1970s, some Japanese set manufacturers developed decoding systems to avoid paying royalties to Telefunken
Telefunken was a German radio and television apparatus company, founded in Berlin in 1903, as a joint venture of Siemens & Halske and the ''Allgemeine Elektrizitäts-Gesellschaft'' (AEG) ('General electricity company').
The name "Telefunken" app ...
. 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''"; unrelated to the broadcast systems with similar designations). This excluded very basic PAL decoders that relied on the human eye to average out the odd/even line phase errors. This variations of the system is known as "PAL-S
PAL-S is the system of television receiver sets in the early days of the PAL system. Here PAL stands for ''Phase alternating at line rate'' and S stands for ''simple''.
PAL system
The color hue modulates the phase of a subcarrier named colo ...
" (for "simple" or “Volks-PAL”), operating without a delay line and suffering from the “ Hannover bars” effect, and for example was used on the ''Kuba Porta Color CK211P'' set. Another solution was to use a 1H analogue delay line
Analog or analogue may refer to:
Computing and electronics
* Analog signal, in which information is encoded in a continuous variable
** Analog device, an apparatus that operates on analog signals
*** Analog electronics, circuits which use analog ...
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
, commonly stylized as SONY, is a Japanese multinational conglomerate corporation headquartered in Minato, Tokyo, Japan. As a major technology company, it operates as one of the world's largest manufacturers of consumer and professional ...
on their 1970s Trinitron
Trinitron was Sony's brand name for its line of aperture-grille-based CRTs used in television sets and computer monitors. One of the first truly innovative television systems to enter the market since the 1950s, the Trinitron was announced in ...
sets (''KV-1300UB'' to ''KV-1330UB''), and came in two versions: "PAL-H" and "PAL-K" (averaging over multiple lines). It effectively converted PAL to NTSC, suffering from hue errors and other problems inherent in NTSC and required the addition of a manual hue
In color theory, hue is one of the main properties (called Color appearance model#Color appearance parameters, color appearance parameters) of a color, defined technically in the CIECAM02 model as "the degree to which a Stimulus (physiology ...
control.
In 1993, an evolution of PAL aimed to improve and enhance format by allowing 16:9 aspect ratio broadcasts, while remaining compatible with existing television receivers, was introduced. Named PALplus
PALplus (or ''PAL+'') is an analogue television broadcasting system aimed to improve and enhance the PAL format by allowing 16:9 (or 1.77:1) aspect ratio broadcasts, while remaining compatible with existing television receivers, defined by ITU re ...
, it was defined by ITU
The International Telecommunication Union is a specialized agency of the United Nations responsible for many matters related to information and communication technologies. It was established on 17 May 1865 as the International Telegraph Unio ...
recommendation BT.1197-1. It was developed at the University of Dortmund
TU Dortmund University (german: Technische Universität Dortmund) is a technical university in Dortmund, North Rhine-Westphalia, Germany with over 35,000 students, and over 6,000 staff including 300 professors, offering around 80 Bachelor's and ...
in Germany
Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated betwe ...
, 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
The DVD (common abbreviation for Digital Video Disc or Digital Versatile Disc) is a digital optical disc data storage format. It was invented and developed in 1995 and first released on November 1, 1996, in Japan. The medium can store any kin ...
, game consoles), the term PAL was used imprecisely to refer to the 625-line 625-lines is a standard-definition television resolution used mainly in the context of analog systems. It was first demonstrated by Mark Iosifovich Krivosheev in 1948.
Analog broadcast television standards
The following International Telecommunic ...
/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) even though technically the discs carry neither PAL nor NTSC encoded signal. These devices would still have analog outputs (ex; composite video
Composite video is an analog video signal format that carries standard-definition video (typically at 525 lines or 625 lines) as a single channel. Video information is encoded on one channel, unlike the higher-quality S-Video (two channels) a ...
output), and would convert the digital signals (576i
576i is a standard-definition television, standard-definition digital video mode, originally used for digitizing analog television in most countries of the world where the utility frequency for electric power distribution is 50 Hz. Because ...
or 480i
480i is the video mode used for standard-definition digital television in the Caribbean, Japan, South Korea, Taiwan, Philippines, Laos, Western Sahara, and most of the Americas (with the exception of Argentina, Paraguay, and Uruguay). The ''480 ...
) 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.
Colour encoding
Most PAL systems encode the colour information using a variant of the Y'UV
YUV is a color model typically used as part of a color image pipeline. It encodes a color image or video taking human perception into account, allowing reduced bandwidth for chrominance components, compared to a "direct" RGB-representation. His ...
colour space. comprises the monochrome ''luma'' signal, with the three RGB colour channels mixed down onto two, and .
Like NTSC, PAL uses a quadrature amplitude modulated subcarrier
A subcarrier is a sideband of a radio frequency carrier wave, which is modulated to send additional information. Examples include the provision of colour in a black and white television system or the provision of stereo in a monophonic radio broa ...
carrying the ''chrominance'' information added to the luma video signal to form a composite video
Composite video is an analog video signal format that carries standard-definition video (typically at 525 lines or 625 lines) as a single channel. Video information is encoded on one channel, unlike the higher-quality S-Video (two channels) a ...
baseband signal. The frequency of this subcarrier is 4.43361875 MHz
The hertz (symbol: Hz) is the unit of frequency in the International System of Units (SI), equivalent to one event (or cycle) per second. The hertz is an SI derived unit whose expression in terms of SI base units is s−1, meaning that one he ...
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
Hanover bars, in one of the PAL television video formats, are an undesirable visual artifact in the reception of a television image. The name refers to the city of Hannover, in which the PAL system developer Telefunken Fernseh und Rundfunk GmbH ...
on larger phase errors. Thus, most receivers now use a chrominance analogue delay line
Analog or analogue may refer to:
Computing and electronics
* Analog signal, in which information is encoded in a continuous variable
** Analog device, an apparatus that operates on analog signals
*** Analog electronics, circuits which use analog ...
, 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
Saturation, saturated, unsaturation or unsaturated may refer to:
Chemistry
* Saturation, a property of organic compounds referring to carbon-carbon bonds
**Saturated and unsaturated compounds
** Degree of unsaturation
**Saturated fat or fatty aci ...
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.
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
In telecommunications, a carrier wave, carrier signal, or just carrier, is a waveform (usually sinusoidal) that is modulated (modified) with an information-bearing signal for the purpose of conveying information. This carrier wave usually has a m ...
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
Carrier may refer to:
Entertainment
* ''Carrier'' (album), a 2013 album by The Dodos
* ''Carrier'' (board game), a South Pacific World War II board game
* ''Carrier'' (TV series), a ten-part documentary miniseries that aired on PBS in April 20 ...
is required by the colour decoder to recreate the colour difference
In color science, color difference or color distance is the separation between two colors. This metric allows quantified examination of a notion that formerly could only be described with adjectives. Quantification of these properties is of great ...
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
Phase or phases may refer to:
Science
*State of matter, or phase, one of the distinct forms in which matter can exist
*Phase (matter), a region of space throughout which all physical properties are essentially uniform
* Phase space, a mathematic ...
of this locally generated signal can match the transmitted information, a 10 cycle burst of colour subcarrier
A subcarrier is a sideband of a radio frequency carrier wave, which is modulated to send additional information. Examples include the provision of colour in a black and white television system or the provision of stereo in a monophonic radio broa ...
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 vector which reverses every line.
PAL signal details
For PAL-B/G the signal has these characteristics.
(Total horizontal sync time 12.05 µs)
After 0.9 µs a colourburst of cycles is sent. Most rise/fall times are in range. Amplitude is 100% for white level, 30% for black, and 0% for sync.
The CVBS
Composite video is an analog video signal format that carries standard-definition video (typically at 525 lines or 625 lines) as a single channel. Video information is encoded on one channel, unlike the higher-quality S-Video (two channels ...
electrical amplitude is Vpp and impedance of 75 Ω.[ 090426 thomsongrassvalley.com]
The vertical timings are:
(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
The CIE 1931 color spaces are the first defined quantitative links between distributions of wavelengths in the electromagnetic visible spectrum, and physiologically perceived colors in human color vision. The mathematical relationships that defin ...
x,y coordinates:
The assumed display gamma is defined as 2.8. PAL-N
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 ...
uses YDbDr
YDbDr, sometimes written YDBDR, is the colour space used in the SECAM analog terrestrial colour television broadcasting standard (adopted in France and some countries of the former Eastern Bloc) and PAL-N (adopted in Argentina, Paraguay and Urugua ...
instead of YUV. The PAL-M
PAL-M is the analogue TV system used in Brazil since 19 February 1972. At that time, Brazil was the first South American country to broadcast in colour. Colour TV broadcast began on 19 February 1972, when the TV networks Globo and Bandeirantes t ...
system uses color primary and gamma values similar to NTSC.
Color is encoded using the YUV
YUV is a color model typically used as part of a color image pipeline. It encodes a color image or video taking human perception into account, allowing reduced bandwidth for chrominance components, compared to a "direct" RGB-representation. H ...
color space. Luma
Luma or LUMA may refer to:
Arts
* La Trobe University Museum of Art, Melbourne, Australia
* LUMA Projection Arts Festival, an annual event featuring building-scale projection mapping and light installations in Binghamton, NY
* LUMA Foundation, ...
() is derived from red, green, and blue () gamma pre-corrected () primary signals:
*
and are used to transmit chrominance
Chrominance (''chroma'' or ''C'' for short) is the signal used in video systems to convey the color information of the picture (see YUV color model), separately from the accompanying luma signal (or Y' for short). Chrominance is usually represente ...
. Each has a typical bandwidth of 1.3 MHz.
*
*
Composite PAL signal timing where .
Subcarrier frequency 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
The refresh rate (or "vertical refresh rate", "vertical scan rate", terminology originating with the cathode ray tubes) is the number of times per second that a raster-based display device displays a new image. This is independent from frame rate ...
of 50 interlaced
Interlaced video (also known as interlaced scan) is a technique for doubling the perceived frame rate of a video display without consuming extra bandwidth. The interlaced signal contains two fields of a video frame captured consecutively. This ...
fields per second (compatible with 25 full frames per second), such systems being B, G, H, I, and N (see broadcast television system
Broadcast television systems (or terrestrial television systems outside the US and Canada) are the encoding or formatting systems for the transmission and reception of terrestrial television signals.
Analog television systems were standardized by ...
s 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
Eastern Europe is a subregion of the Europe, European continent. As a largely ambiguous term, it has a wide range of geopolitical, geographical, ethnic, cultural, and socio-economic connotations. The vast majority of the region is covered by Russ ...
which formerly used SECAM
SECAM, also written SÉCAM (, ''Séquentiel de couleur à mémoire'', French for ''color sequential with memory''), is an analog color television system that was used in France, some parts of Europe and Africa, and Russia. It was one of th ...
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.
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.
System A
The BBC tested their pre-war (but still broadcast until 1985) 405-line monochrome system (CCIR System A
CCIR System A was the 405-line analog broadcast television system adopted in the UK and Ireland. System A service started in 1936 and was discontinued in 1985.
Specifications
Some of the important specs are listed below.
A frame is the t ...
) 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, South Asia, Australia, and New Zealand
* Standard I in the UK, Ireland, Hong Kong, South Africa, and Macau
* Standards D/ K (along with SECAM) in most of Central and Eastern Europe
* Standard D in mainland China. Most analogue CCTV cameras are Standard D.
Systems B and G are similar. System B specifies 7 MHz channel bandwidth, while System G specifies 8 MHz channel bandwidth. Australia used System B 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 (except in mainland China), 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
CCIR System L is an analog broadcast television system used in France and Luxemburg. It was the last system to use positive video modulation and AM sound.
Initially adopted in the 1970s and associated with the SECAM color system (SECAM-L), it wa ...
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
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 ...
variant is used (Phase Alternating Line with CCIR System N
CCIR System N is an analog broadcast television system introduced in 1951 and adopted by Argentina, Paraguay and Uruguay (since 1980), paired with the PAL color system (PAL-N). It was also used briefly in Brazil and Venezuela.
It employs the 625 ...
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
YDbDr, sometimes written YDBDR, is the colour space used in the SECAM analog terrestrial colour television broadcasting standard (adopted in France and some countries of the former Eastern Bloc) and PAL-N (adopted in Argentina, Paraguay and Urugua ...
colour space.
Extended features of the PAL specification, such as Teletext
A British Ceefax football index page from October 2009, showing the three-digit page numbers for a variety of football news stories
Teletext, or broadcast teletext, is a standard for displaying text and rudimentary graphics on suitably equipp ...
, are implemented quite differently in PAL-N. PAL-N supports a modified 608 closed captioning
Closed captioning (CC) and subtitling are both processes of displaying text on a television, video screen, or other visual display to provide additional or interpretive information. Both are typically used as a transcription of the audio por ...
format that is designed to ease compatibility with NTSC originated NABTS
NABTS, the North American Broadcast Teletext Specification, is a protocol used for encoding NAPLPS-encoded teletext pages, as well as other types of digital data, within the vertical blanking interval (VBI) of an analog video signal. It is standard ...
content carried on line 18, and a modified teletext format that can occupy several lines.
PAL-M (Brazil)
In Brazil, PAL is used in conjunction with the 525 line, 59.94 field/s CCIR System M
CCIR System M, sometimes called 525–line, monochrome NTSC or NTSC-M, is the analog broadcast television system approved by the FCC (upon recommendation by the National Television Systems Committee - NTSC) for use in the United States since ...
, 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 (480i
480i is the video mode used for standard-definition digital television in the Caribbean, Japan, South Korea, Taiwan, Philippines, Laos, Western Sahara, and most of the Americas (with the exception of Argentina, Paraguay, and Uruguay). The ''480 ...
) 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
Composite video is an analog video signal format that carries standard-definition video (typically at 525 lines or 625 lines) as a single channel. Video information is encoded on one channel, unlike the higher-quality S-Video (two channels ...
or S-video
S-Video (also known as separate video, Y/C, and erroneously Super-Video ) is an analog video signal format that carries standard-definition video, typically at 525 lines or 625 lines. It encodes video luma and chrominance on two separate channe ...
SECAM signals. Many can also accept baseband
In telecommunications and signal processing, baseband is the range of frequencies occupied by a signal that has not been modulated to higher frequencies. Baseband signals typically originate from transducers, converting some other variable into a ...
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
DirecTV (trademarked as DIRECTV) is an American multichannel video programming distributor based in El Segundo, California. Originally launched on June 17, 1994, its primary service is a digital satellite service serving the United States. It ...
also conveniently broadcasts in NTSC-M for North, Central, and South America. Most DVD
The DVD (common abbreviation for Digital Video Disc or Digital Versatile Disc) is a digital optical disc data storage format. It was invented and developed in 1995 and first released on November 1, 1996, in Japan. The medium can store any kin ...
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
SCART (also known as or , especially in France, 21-pin EuroSCART in marketing by Sharp in Asia, Euroconector in Spain, EuroAV or EXT, or EIA Multiport in the United States, as an EIA interface) is a French-originated standard and associated 21- ...
) 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
Transcoding is the direct digital-to-digital conversion of one encoding to another, such as for video data files, audio files (e.g., MP3, WAV), or character encoding (e.g., UTF-8, ISO/IEC 8859). This is usually done in cases where a target devic ...
(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 recorder
A videocassette recorder (VCR) or video recorder is an electromechanical device that records analog audio and analog video from broadcast television or other source on a removable, magnetic tape videocassette
Videotape is magnetic tape ...
s 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 Sega Dreamcast
The is a home video game console released by Sega on November 27, 1998, in Japan; September 9, 1999, in North America; and October 14, 1999, in Europe. It was the first sixth-generation video game console, preceding Sony's PlayStation 2, Nint ...
pioneered PAL 60 with most of its games being able to play games at full speed like NTSC and without borders. Microsoft Xbox
Xbox is a video gaming brand created and owned by Microsoft. The brand consists of five video game consoles, as well as applications (games), streaming services, an online service by the name of Xbox network, and the development arm by the na ...
and Nintendo GameCube
The is a home video game console developed and released by Nintendo in Japan on September 14, 2001, in North America on November 18, 2001, and in PAL territories in 2002. It is the successor to the Nintendo 64 (1996), and predecessor of the Wii ...
also had high support for PAL 60 unlike PlayStation 2. The PlayStation 2
The PlayStation 2 (PS2) is a home video game console developed and marketed by Sony Computer Entertainment. It was first released in Japan on 4 March 2000, in North America on 26 October 2000, in Europe on 24 November 2000, and in Australia on 3 ...
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.
PAL vs. NTSC
PAL usually has 576 visible lines compared with 480 lines with NTSC
The first American standard for analog television broadcast was developed by National Television System Committee (NTSC)National Television System Committee (1951–1953), Report and Reports of Panel No. 11, 11-A, 12–19, with Some supplement ...
, 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
The first American standard for analog television broadcast was developed by National Television System Committee (NTSC)National Television System Committee (1951–1953), Report and Reports of Panel No. 11, 11-A, 12–19, with Some supplement ...
is used with a frame rate
Frame rate (expressed in or FPS) is the frequency (rate) at which consecutive images (frames) are captured or displayed. The term applies equally to film and video cameras, computer graphics, and motion capture systems. Frame rate may also be ca ...
of 60i or 30p whereas PAL generally uses 50i or 25p; both use a high enough frame rate
Frame rate (expressed in or FPS) is the frequency (rate) at which consecutive images (frames) are captured or displayed. The term applies equally to film and video cameras, computer graphics, and motion capture systems. Frame rate may also be ca ...
to give the illusion of fluid motion. This is due to the fact that NTSC is generally used in countries with a utility frequency
The utility frequency, (power) line frequency (American English) or mains frequency (British English) is the nominal frequency of the oscillations of alternating current (AC) in a wide area synchronous grid transmitted from a power station to th ...
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 Because the NTSC color television standard relies on the absolute phase of the color information, color errors occur when the phase of the video signal is altered between source and receiver, or due to non linearities in electronics. To correct fo ...
to perform colour correction manually. If this is not adjusted correctly, the colours may be faulty. The PAL standard automatically cancels hue
In color theory, hue is one of the main properties (called Color appearance model#Color appearance parameters, color appearance parameters) of a color, defined technically in the CIECAM02 model as "the degree to which a Stimulus (physiology ...
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
Hanover bars, in one of the PAL television video formats, are an undesirable visual artifact in the reception of a television image. The name refers to the city of Hannover, in which the PAL system developer Telefunken Fernseh und Rundfunk GmbH ...
—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 space
A color space is a specific organization of colors. In combination with color profiling supported by various physical devices, it supports reproducible representations of colorwhether such representation entails an analog or a digital representa ...
s, but the colour decoder differences here are ignored.
Outside of film and TV broadcasts, the differences between the two formats when displaying video games
Video games, also known as computer games, are electronic games that involves interaction with a user interface or input device such as a joystick, game controller, controller, computer keyboard, keyboard, or motion sensing device to gener ...
are quite dramatic. Games ported to PAL have historically been known for having game speed and frame rates inferior to their NTSC counterparts, being typically slowed by approximately 16.7% in order to avoid timing problems or unfeasible code changes. Full motion video rendered and encoded at 30 frames per second by the Japanese/US (NTSC) developers was often down-sampled to 25 frames per second or considered to be 50 frames per second video for PAL release—usually by means of 3:2 pull-down, resulting in motion judder. In addition to this, PAL's increased resolution was not utilised during conversion, creating a pseudo letterbox effect with borders top and bottom, which looks similar to a 14:9 letterbox, and leaving the graphics with a slightly squashed look due to an incorrect aspect ratio caused by the borders. This was especially prevalent during the 8-bit and 16-bit generations when 2D graphics were used almost exclusively. The gameplay of many games with an emphasis on speed, such as the original Sonic the Hedgehog for the Sega Genesis/Mega Drive, suffered in their PAL incarnations, although also made them slightly easier.
Despite the possibility and popularity of 60 Hz games in PAL regions, many high-profile games, particularly for the PlayStation 2 console, were released in 50 Hz-only versions. Square Enix have long been criticised by PAL gamers for their poor PAL conversions. Final Fantasy X, for example, runs in 50 Hz mode only, meaning it runs 16.7% slower than the NTSC release and features top and bottom borders. While this practice was common in previous generations, it was considered inexcusable by contemporary consumers at the time of release, due to the availability of TV sets supporting a 60Hz scan rate with PAL colour (see "PAL 60" above) and RGB
The RGB color model is an additive color model in which the red, green and blue primary colors of light are added together in various ways to reproduce a broad array of colors. The name of the model comes from the initials of the three addi ...
or component
Circuit Component may refer to:
•Are devices that perform functions when they are connected in a circuit.
In engineering, science, and technology Generic systems
*System components, an entity with discrete structure, such as an assemb ...
connections that allow colour output without the need for NTSC or PAL color encoding.
In contrast, the Dreamcast
The is a home video game console released by Sega on November 27, 1998, in Japan; September 9, 1999, in North America; and October 14, 1999, in Europe. It was the first sixth-generation video game console, preceding Sony's PlayStation 2, N ...
was the first system to feature "PAL 60", and the overwhelming majority of PAL games offered 50 and 60 Hz modes with no slow speeds. Xbox
Xbox is a video gaming brand created and owned by Microsoft. The brand consists of five video game consoles, as well as applications (games), streaming services, an online service by the name of Xbox network, and the development arm by the na ...
and GameCube
The is a home video game console developed and released by Nintendo in Japan on September 14, 2001, in North America on November 18, 2001, and in PAL territories in 2002. It is the successor to the Nintendo 64 (1996), and predecessor of the Wii ...
also had high "PAL 60" support.
PAL vs. SECAM
The SECAM
SECAM, also written SÉCAM (, ''Séquentiel de couleur à mémoire'', French for ''color sequential with memory''), is an analog color television system that was used in France, some parts of Europe and Africa, and Russia. It was one of th ...
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
In color theory, hue is one of the main properties (called Color appearance model#Color appearance parameters, color appearance parameters) of a color, defined technically in the CIECAM02 model as "the degree to which a Stimulus (physiology ...
problems, came up with ideas that were to become fundamental to both European systems, namely:
# colour information on two successive TV lines is very similar and vertical resolution can be halved without serious impact on perceived visual quality
# more robust colour transmission can be achieved by spreading information on two TV lines instead of just one
# 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
Frequency modulation (FM) is the encoding of information in a carrier wave by varying the instantaneous frequency of the wave. The technology is used in telecommunications, radio broadcasting, signal processing, and Run-length limited#FM: .280. ...
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
PAL-S is the system of television receiver sets in the early days of the PAL system. Here PAL stands for ''Phase alternating at line rate'' and S stands for ''simple''.
PAL system
The color hue modulates the phase of a subcarrier named colo ...
), 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).
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
SCART (also known as or , especially in France, 21-pin EuroSCART in marketing by Sharp in Asia, Euroconector in Spain, EuroAV or EXT, or EIA Multiport in the United States, as an EIA interface) is a French-originated standard and associated 21- ...
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["Les Videodisques", Georges Broussaud (head/member of development team), editions Masson]). 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 using PAL
See also
* 576i
576i is a standard-definition television, standard-definition digital video mode, originally used for digitizing analog television in most countries of the world where the utility frequency for electric power distribution is 50 Hz. Because ...
* PALplus
PALplus (or ''PAL+'') is an analogue television broadcasting system aimed to improve and enhance the PAL format by allowing 16:9 (or 1.77:1) aspect ratio broadcasts, while remaining compatible with existing television receivers, defined by ITU re ...
* Hanover bars
Hanover bars, in one of the PAL television video formats, are an undesirable visual artifact in the reception of a television image. The name refers to the city of Hannover, in which the PAL system developer Telefunken Fernseh und Rundfunk GmbH ...
* Digital Video Broadcasting
Digital Video Broadcasting (DVB) is a set of international open standards for digital television. DVB standards are maintained by the DVB Project, an international industry consortium, and are published by a Joint Technical Committee (JTC) ...
* Moving image formats
This 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
The essential parameters of any moving image sequence a ...
* Prewar television stations
This is a list of pre-World War 2 television stations of the 1920s and 1930s. Most of these experimental stations were located in Europe (notably in the United Kingdom, France, Germany, Italy, Poland, the Netherlands, and Russia), Australia, Can ...
* Broadcast-safe
Broadcast-safe video (broadcast legal or legal signal) 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 broadcastin ...
* Differential gain
Differential gain is a kind of linearity distortion which affects the color saturation in TV broadcasting.
Composite color video signal
Composite color video signal (CCVS) consists of three terms:
*Luminance (monochrome) signal
*Auxiliary si ...
* YUV
YUV is a color model typically used as part of a color image pipeline. It encodes a color image or video taking human perception into account, allowing reduced bandwidth for chrominance components, compared to a "direct" RGB-representation. H ...
* D1 SMPTE
D-1 or 4:2:2 Component Digital is an SMPTE digital recording video standard, introduced in 1986 through efforts by SMPTE engineering committees. It started as a Sony and Bosch - BTS product and was the first major professional digital video f ...
* D-2 (video)
D-2 is a professional digital videocassette format created by Ampex and introduced in 1988 at the NAB Show as a composite video alternative to the component video D-1 format. It garnered Ampex a technical Emmy in 1989. Like D-1, D-2 stores un ...
References
External links
Review of the different refresh rates of PAL, NTSC and motion picture films
{{Telecommunications
ITU-R recommendations
Television technology
Television terminology
Television transmission standards
Video formats
German inventions
1963 introductions