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PAL

PAL, short for Phase Alternating Line, Phase Alternation by Line or for Phase Alternation Line, is a colour encoding used in broadcast television systems, used throughout the world except in most of the Americas, some East Asian countries, parts of the Middle East and Eastern Europe, and France. PAL was developed in Germany by Walter Bruch, working at Telefunken, and first introduced in 1967.

Note that French Thomson, where Henri de France developed SECAM, later bought Telefunken. Thomson is also behind the RCA brand for consumer electronics products, and RCA created the NTSC color TV standard.

Table of contents

1 Technical details 2 Countries and territories which use PAL 2.1 Europe 2.2 Asia 2.3 The Americas 2.4 Africa 2.5 Australia and Oceania 3 Countries which use PAL-I 4 Countries which use PAL-M 5 Countries which use PAL-N 6 Reference 7 See also 8 External Links

Technical details

The name "Phase Alternating Line" describes the way that part of the colour information on the video signal is reversed in phase with each line, which automatically corrects phase errors in the transmission of the signal. NTSC receivers have a tint control to perform the correction manually. Some engineers jokingly expand NTSC to "Never Twice the Same Colour" while referring to PAL as "Perfect At Last" or "Peace At Last"! However, the alternation of colour information - Hanover bars - can lead to picture grain on pictures with extreme phase errors.

The PAL colour system is usually used with a video format that has 625 lines per frame and a refresh rate of 25 frames per second, interlaced, such as systems B, G, H, I, and N (see broadcast television systems for the technical details of each format). 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. (However, some other countries changed completely from SECAM-D/K to PAL-B/G.) In Brazil, PAL is used in conjunction with the 525 line, 29.97 frame/s system M (other countries using system M use NTSC). Recently-manufactured television receivers can typically decode all of these systems, except in some cases PAL-M.

When video is transmitted baseband, most of the differences between systems are no longer significant, other than vertical resolution and frame rate, and in that context, unqualified PAL invariably means 625 lines at 25 frames per second, interlaced, with PAL color.

Countries and territories which use PAL

Europe

Asia

The Americas

Africa

Australia and Oceania

Countries which use PAL-I

Countries which use PAL-M

Countries which use PAL-N

Reference

• The standard that defines the PAL system was published by the International Telecommunications Union in 1998 and has the title Recommendation ITU-R BT.470-6, Conventional Television Systems.

• PALplus
• Broadcast television systems

• More information about TV standards
• PAL to NTSC Conversion

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