pal n : a close friend who accompanies his buddies in their activities [syn: buddy, brother, chum, crony, sidekick] v : become friends; act friendly towards [syn: pal up, chum up] [also: palling, palled]
EtymologyFrom Romani phral.
- Rhymes: -æl
- Be friends with, hang around with.
- John plans to pal around with Joe today.
- English: pole
PAL, short for Phase Alternating Line, is a colour encoding system used in broadcast television systems in large parts of the world. Other common analog television systems are SECAM and NTSC. This page discusses the colour encoding system only. See Broadcast television systems and analog television for discussion of frame rates, image resolution and audio modulation. For discussion of the 625-line 25 frame/s television standard, see 576i.
History of the PAL standardIn the 1950s, when the Western European countries were planning to establish colour television, they were faced with the problem that the already existing American NTSC standard wouldn't fit the 50 Hz AC frequency of the European power grids. In addition to that NTSC demonstrated several weaknesses, including colour tone shifting under less-than-ideal transmission conditions. For these reasons the development of the SECAM and PAL standards began. The goal was to provide a colour TV standard with a picture frequency of 50 fields per second (50 hertz), and sporting a better colour picture than NTSC.
PAL was developed by Walter Bruch at Telefunken in Germany. The format was first unveiled in 1963, with the first broadcasts beginning in the United Kingdom and Germany in 1967.
Telefunken was later bought by the French electronics manufacturer Thomson. Thomson also bought the Compagnie Générale de Télévision where Henri de France developed SECAM, historically the first European colour television standard. Thomson nowadays also co-owns the RCA brand for consumer electronics products, which created the NTSC colour TV standard before Thomson became involved.
The term PAL is often used informally to refer to a 625-line/50 Hz (576i, principally European) television system, and to differentiate from a 525-line/60 Hz (480i, principally North American/Central American/Japanese) NTSC system. Accordingly, DVDs are labelled as either PAL or NTSC (referring informally to the line count and frame rate) even though technically the European discs do not have PAL composite colour. This usage may lead readers to believe that PAL defines image resolution, even though it doesn't. The PAL colour system can be used in conjunction with any resolution and frame rate, and various such combinations exist. NTSC, by contrast does define the video line and frame format.
The basics of PAL and the NTSC system are very similar; a quadrature amplitude modulated subcarrier carrying the chrominance information is added to the luminance video signal to form a composite video baseband signal. The frequency of this subcarrier is approximately 4.43 MHz for PAL, compared to approximately 3.58 MHz for NTSC. The SECAM system, on the other hand, uses a frequency modulation scheme on its colour subcarrier.
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. 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 imperfections of the human eye to do that cancelling; however this resulted in a comb-like effect on larger phase errors. Thus, most receivers now use a chrominance 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 luminance signal.
For a 1:1 pixel aspect (square pixels) on a 50 Hz interlaced PAL signal the pixel rate should be 14.75 MHz.
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 is 15625 Hz, the colour carrier frequency calculates as follows: 4.43361875 MHz = 283.75 * 15625 Hz + 25 Hz.
PAL vs. NTSCNTSC receivers have a tint control to perform colour correction manually. If this isn't adjusted correctly, the colours may be faulty. The PAL standard automatically removes hue errors by utilizing phase alternation of the colour signal (see technical details), so a tint control is unnecessary. Chrominance phase errors in the PAL system are cancelled out using a 1H delay line resulting 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 mis-aligned or use the simplified decoders of early designs (to overcome royalty restrictions). Usually such extreme phase shifts do not occur; 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 signals than VHF as VHF signals tend to be more robust.
A PAL decoder can be seen as a pair of NTSC decoders:
- PAL can be decoded with two NTSC decoders.
- By switching between the two NTSC decoders every other line it is possible to decode PAL without a phase delay line or two phase-locked loop (PLL) circuits.
- This works because one decoder receives a colour sub carrier with negated phase in relation to the other decoder. It then negates the phase of that sub carrier when decoding. This leads to smaller phase errors being cancelled out. However a delay line PAL decoder gives superior performance. Some Japanese TVs originally used the dual NTSC method to avoid paying royalty to Telefunken.
- PAL and NTSC have slightly divergent colour spaces, but the colour decoder differences here are ignored.
- PAL supports SMPTE 498.3 while NTSC is compliant with EBU Recommendation 14.
- The issue of frame rates and colour sub carriers is ignored in this technical explanation. These technical details play no direct role (except as subsystems and physical parameters) to the decoding of the signal.
PAL vs. SECAMSECAM is an earlier attempt at compatible colour television which also tries to resolve the NTSC hue problem. It does so by applying a different method to colour transmission, namely alternate transmission of the U and V vectors and frequency modulation, while PAL attempts to improve on the NTSC method.
SECAM transmissions are more robust over long distances than NTSC or PAL. However due 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. Like PAL, a SECAM receiver needs a delay line.
Broadcast systems PAL has been used with
PAL B/G/D/K/IThe majority of countries using PAL have television standards with 625 lines and 25 frames, differences concern the audio carrier frequency and channel bandwidths. Standards B/G are used in most of Western Europe, standard I in the UK and Ireland, standards D/K in most of Eastern Europe.
7-MHz channels are used in VHF (B, D) and 8-MHz channels in UHF (G, K, I), although Australia used 7-MHz channels in UHF and Ireland uses 8-MHz channels in VHF.
PAL-M standard (Brazil)In Brazil, PAL is used in conjunction with the 525 line, 29.97 frame/s system M, using (very nearly) the NTSC colour subcarrier frequency. Exact colour subcarrier frequency of PAL-M is 3.575611 MHz
- 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) picture to form what is often known as "PAL-60" (sometimes "PAL-60/525" or "Pseudo PAL"). PAL-M (a broadcast standard) however should not be confused with "PAL-60" (a video playback system — see above).
PAL-NcIn Argentina, the PAL-Nc (combination N) variant is used. It employs the 625 line/50 field per second waveform of PAL-B/G,D/K,H,I but with a chrominance sub-carrier frequency of 3.582 MHz. VHS tapes recorded from a PAL-Nc or a PAL-B/G,D/K,H,I broadcast are indistinguishable.
PAL-NIn Paraguay and Uruguay, PAL is used with the standard 625 line/50 fields per second system, but again with (very nearly) the NTSC colour
- PAL-N should not be viewed as wildly incompatible versions of the PAL system, only the choice of colour subcarrier is different.
- 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 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 has been very convenient for video collectors in the past.
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 content carried on line 18, and a modified teletext format that can occur several lines.
PAL LThe PAL L (Phase Alternating Line with L-sound system) standard uses the System "PAL" video standard, which is the same as PAL B/G/H (625 lines, 50 Hz field rate, 15.625 kHz line rate) except that it uses 6 MHz video bandwidth rather than 5.5 MHz, lifting the audio subcarrier to 6.5 MHz. When System L is used with SECAM, the audio carrier is amplitude modulated, but when used with PAL, the more usual FM sound system is usually used. The sound offset in B and G is +5.5 whereas in L its +6.5. In layman's language, PAL-L is PAL-BG with positive and AM sound modulation. An 8 MHz channel spacing is used with PAL L.
PAL L is used on some hotel internal distribution systems, as well as other public display and plant television systems. It is not used by any national TV networks. One example of a TV with PAL-L support is Thomson 24WK25. This signal has been defined by Sandipan Bhattacharjee, India.
All PAL systems interoperable except PAL-M (525/60)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 (i.e. 25 full frames per second), such as systems B, G, H, I, and N (see broadcast television systems for the technical details of each format).
On RF (i.e. via a Modulator or TV Aerial) the difference between I, D/H and B/G is audio. These use different audio subcarriers, so with mismatch on Modulator Settings or an imported TV there will be perfectly normal Colour Video, but possibly no audio. Some TVs and VHS tuners have multiple filters in parallel or switched for the 6 MHz, 5.5 MHz, 6.5 MHz or 4.5 MHz sound carriers. Nicam is an additional 6.5 MHz offset carrier carrying stereo digitally, on 6.0 MHz PAL I systems. Germany particularly uses two separate FM sound carriers on PAL B/G. (Stereo FM Radio uses a mono signal with a DSBSC L-R audio centred on 38 kHz with a 19 kHz pilot to aid decoding. Hence the German Zweiton and Nicam both give better performance than FM Radio).
Multisystem PAL support and "PAL 60"Recently manufactured PAL television receivers can typically decode all of these systems except, in some cases, PAL-M and PAL-N. Many of them can also receive Eastern European and Middle Eastern SECAM, though rarely French broadcast SECAM (because France uses the unique positive video modulation), unless they are made for the French market. They will correctly display plain CVBS or S-video SECAM signals. Many can also accept baseband NTSC-M, such as from a VCR or game console, though not usually broadcast NTSC. Many sets also support NTSC with a 4.43 MHz subcarrier.
Many newer Video Cassette recorders and DVD players sold in Europe can play back NTSC tapes/discs. When operating in this mode most of them don't output a true (625/25) PAL signal but rather a hybrid of PAL and NTSC known as "PAL 60" (or "pseudo PAL") with "60" standing for 60 Hz, instead of 50 Hz. Some video game consoles also output a signal in this mode. Most newer television sets can display such a 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 (it can be noted, however, that many analogue-era TV sets can receive the picture by means of adjusting the V-Hold and V-Height knobs — assuming they have them). Very few TV tuner cards or video capture cards will support this mode (a small number can, although software/driver modification is usually required and the manufacturers specs are usually unclear). A "PAL 60" signal is similar to an NTSC (525/30) signal but with a PAL chrominance subcarrier at 4.43 MHz (instead of 3.58) and with the PAL-specific phase alternation of the red colour difference signal between the lines.
Countries and territories using PALOver 120 countries and territories use or once used the terrestrial PAL system. Many of these are currently converting terrestrial PAL to DVB-T (PAL still often used via cable TV).
PAL B, G, D, K or I
- flag Afghanistan
- flag Albania DVB-T introduction started in 2005
- flag Australia DVB-T introduction started in 2001 (PAL to be abandoned for DVB-T by 2012)
- flag Austria DVB-T introduction started in 2006
- flag Bahrain
- flag Bangladesh
- flag Belgium
- flag Bosnia and Herzegovina
- flag Brunei
- flag Bulgaria (migrated from SECAM 1994 - 1996) (set to migrate to DVB-T in 2012, although such broadcasts are currently only available in Sofia)
- flag China, Mainland (PAL-D, digital broadcast using DMB-T/H)
- flag Croatia
- flag Cyprus
- flag Czech Republic (migrated from SECAM 1992 - 1994) (DVB-T introduction started in 2006, PAL to be abandoned for DVB-T by 2012)
- flag Denmark (including flag Faroe Islands and flag Greenland) (PAL broadcast to be abandoned by 31 October 2009; DVB-T since 31 March 2006)
- flag East Timor (Timor-Leste)
- flag Estonia (migrated from SECAM 1995 - 1999; PAL to be abandoned for DVB-T at latest in 2012)
- flag Germany (PAL broadcast to be abandoned; DVB-T introduction started in 2003)
- flag Gibraltar
- flag Greece (migrated from SECAM in ca. 1992)
- flag Hungary (migrated from SECAM 1995 - 1996; PAL broadcast to be abandoned by 31 December 2011; is converting to DVB-T)
- flag Iceland
- flag India
- flag Indonesia
- flag Iran
- flag Iraq
- flag Ireland (VHF and UHF)
- flag Israel
- flag Italy (PAL broadcast to be abandoned by 2012; is converting to DVB-T)
- flag Jordan
- flag Kuwait
- flag Latvia (migrated from SECAM 1997 - 1999)
- flag Lebanon
- flag Liechtenstein
- flag Lithuania (migrated from SECAM 1997 - 1999)
- flag Republic of Macedonia
- flag Malaysia (Preliminary DVB-T Trials ended, further trials planned. Set top box and Digital TV not yet available on sale, but USB DVB-T receivers for viewing on a computer are widely available now. Plans to abandon PAL broadcast by 2015)
- flag Maldives
- flag Malta
- flag Montenegro
- flag Myanmar
- flag Nepal
- flag New Zealand
- flag Norway PAL broadcast to be abandoned by 2008–2009, simulcast in DVB-T
- flag Poland (migrated from SECAM 1993 - 1995)
- flag Portugal, including flag Madeira and flag Azores
- flag Romania (PAL broadcast to be abandoned by 2010-2011; is converting to DVB-T since early 2007)
- flag Serbia
- flag Slovenia (PAL broadcast to be abandoned by 2012; is converting to DVB-T)
- flag Slovakia (migrated from SECAM 1993 - 1996)
- flag Spain (including flag Canary Islands) PAL broadcast to be abandoned by 2012, simulcast in DVB-T
- flag Turkey
- flag Ukraine
- flag United Kingdom (UHF only), PAL broadcast to be abandoned by 2012, simulcast in DVB-T
- flag Vatican City
- flag North Korea
- flag Oman
- flag Pakistan
- flag Palestine (Gaza & West Bank)
- flag Qatar
- flag Saudi Arabia (which also uses SECAM)
- flag Singapore
- flag Sri Lanka
- flag Syria
- flag Thailand
- flag United Arab Emirates
- flag Vietnam
- flag Yemen
- flag Botswana
- flag Cameroon
- flag Cape Verde
- flag Egypt
- flag Eritrea
- flag Ethiopia
- flag Gambia
- flag Ghana
- flag Guinea
- flag Kenya
- flag Liberia
- flag Malawi
- flag Mozambique
- flag Morocco
- flag Nigeria
- flag Seychelles
- flag Sierra Leone
- flag Somalia
- flag Sudan
- flag Swaziland
- flag Tanzania
- flag Tunisia
- flag Uganda
- flag Zambia
- flag Zanzibar
- flag Zimbabwe
- flag Angola
- flagicon United Kingdom Ascension Island, PAL broadcast to be abandoned by 2012, simulcast in DVB-T
- flag Lesotho
- flag Namibia
- flag South Africa PAL broadcast to be abandoned by 2011; is converting to DVB-T
- flag Tristan da Cunha
- flag Christmas Island (see Australia)
- flag Cook Islands (see New Zealand)
- flag Easter Island
- flag Fiji
- flag Norfolk Island (see Australia)
- flag Papua New Guinea
- flag Samoa, Samoa is converting to NTSC and probably ATSC
- flag Solomon Islands
- flag Tonga, Tonga is converting to NTSC and probably ATSC
- flag Vanuatu
- flag Falkland Islands (UHF only)
Countries and territories that once used PAL
- flag Andorra (switched to DVB-T completed September 25, 2007)
- flag Finland (switched to DVB-T completed September 1, 2007)
- flag Luxembourg (switched to DVB-Tcompleted September 1, 2006)
- flag Netherlands (switched to DVB-T completed December 11, 2006)
- flag Sweden (switch to DVB-T completed October 15, 2007)
- flag Switzerland (switch to DVB-T completed November 26, 2007)
pal in Afrikaans: PAL
pal in Catalan: PAL
pal in Czech: PAL
pal in Danish: PAL
pal in German: Phase Alternating Line
pal in Spanish: PAL
pal in French: Phase Alternated Line
pal in Korean: PAL
pal in Croatian: PAL
pal in Indonesian: PAL
pal in Italian: Phase alternating line
pal in Hebrew: PAL
pal in Hungarian: PAL
pal in Malay (macrolanguage): PAL
pal in Dutch: Phase Alternating Line
pal in Japanese: PAL
pal in Norwegian: PAL
pal in Polish: PAL
pal in Portuguese: PAL
pal in Romanian: PAL
pal in Russian: PAL
pal in Slovenian: PAL
pal in Finnish: PAL
pal in Swedish: Phase Alternating Line
pal in Turkish: PAL (elektronik)
pal in Chinese: PAL制式
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