What is PAL, Feature, Application

PAL

   PAL is short for Phase Alternating Line was presented by Walter Bruch in 1967 who worked for Telefunken in German.

   PAL is also refers to 625 lines, 25 frame per second, interlaced, the TV system PAL color encoding. PAL is in accordance with the details of the parameters, but also can be further divided into G, I, D, and other formats, including PAL-D system is the standard adopted by China's mainland. These two formats are not compatible with each other. If playing NTSC image on a PAL TV set; the screen becomes black and white, the same as NTSC.

   PAL system, also named Pal system. It was developed for overcoming the sensitivity of the phase distortion of NTSC system. PAL is the abbreviation of Phase Alteration Line means Phase Alternating Line; also belong to the same time system. It takes Phase Alternating Line to one of the two color difference signal which sends in the same time. For another color signal, it uses in quadrature modulation. So if phase distortion happens between the signal transmissions, then will play each other to compensate for the role of the contrary by the two adjacent rows of signal phase for effectively overcome the sky color changes due to phase distortion. Therefore, the PAL system phase distortion is not sensitive with small errors of image color and compatible with black &white TV.

PAL TV standard

   In the PAL television standard, it is 25 frames per second TV scan lines to 625 lines, odd field in the former. Even field in the standard digital PAL TV standard resolution of 720 * 576, 24-bit color is little bit dark and the ratio of the wide and the height of screen 4:3. PAL television standard is used in China, Europe and other countries and regions, the power supply frequency of the PAL system TV is 50Hz field frequency of 50 fields per second frame rate of 25 frames per second scan lines is 625 lines, the image signal bandwidth of 4.2MHz, 5.5MHz, 5.6MHz.The different between PAL and NTSC is that the Color Code of the program, decoding, and field scanning frequency. China (excluding Hong Kong), India, Pakistan and other countries are using the PAL, the United States, Japan, Korea, and China's Taiwan region are adopting NTSC format.

PAL and NTSC both have 24 film frames per second when film screenings. The different between them is that video images of PAL format are 50 fields per second and NTSC system is 60 fields per second. As the TV is interlaced fields nowadays, so we can probably think of there are 25 full video frames per second of PAL and 30 full video frames in a NTSC system. Here is one frame difference between Film and PAL, so the PAL put out one more frame than the film and also improves the speed of 1/24, at the same time, the tone of the voice is raised. This is one of the reasons that DVD fans do not like the PAL system.

It is said that some of PAL DVD adopt 24 +1 production methods which is achieving the same speed as the speed of movie playing by repeating one of the 24 film frames. However, NTSC has 30 frames per second. It cannot be directly produced one file frame by one file frame. As the result, it needs to translate a 24 frames' film to a 30 frames' video via through 3-2 PULLDOWN. It contains the same contents with the film in these 30 frames, so the NTSC's play speed is as same as the film.

PAL system format

PAL itself refers to the color system and often been accompanied by 625 lines, 25 frames per second, interlaced scanning television broadcasting formats: such as B, G, H, I, N and so on. Of course PAL also together with the other resolution formats. For instance, the M-broadcast format which is used in Brazil is 525 lines, 29.97 Grid (the same as NTSC format) which NTSC color subcarrier, but Brazil uses PAL color encoding.

Nowadays, majority of PAL TV sets can cover all different systems PAL format. Many PAL TV sets can play baseband NTSC-M, for example, video game console, VCR with NTSC signal, but they are not necessarily able to receive the NTSC broadcast. When the video signal transmission as a baseband (such as video game console, VCR, etc.), there will be no such things what has been said above, a variety of "letters" to distinguish between broadcast format. In this case, PAL means: 625 scan lines, 25 frames per second, interlaced scanning, PAL color encoding. As for the Digital images such as DVD or digital broadcasting, The color coding also has no difference, at this situation PAL refers to:625 scan lines at 25 frames per second, interlaced scanning that is to say  with the same as SECAM. The United Kingdom, Hong Kong and Macao are using the PAL-I. Mainland China use PAL-D, and Singapore are using the PAL B / G or D / K.

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