The Advantages of PAL TV Systems
PAL is the acronym for Phase Alternating Line in television terminology. It is used to describe a color encoding system that is used in broadcast television systems in most parts of the world. It was Walter Bruch at Telefunken in Germany who had developed PAL, and it was in 1963 that the format was first unveiled. The first broadcasts were in 1967, in United Kingdom and Germany.
PAL TV systems are 625-line/50 Hz television systems and are different from the 525-line/60Hz NTSC television systems. PAL TV systems are predominant in Europe while the NTSC systems are found mostly in North America, Central America and Japan. DVDs that can be played on these systems are accordingly labeled as ‘PAL’ or ‘NTSC’. However European discs usually don’t have PAL composite color while NTSC defines the video line and frame format by contrast.
The PAL TV systems have greater resolution than NTSC and are more accepted because of its higher quality. The NTSC systems have tint controls that correct color manually; and if not corrected properly, colors turn out to be faulty. In the case of PAL TV systems, hue errors are automatically removed with the utilization of phase alternation of color signals it receives. This is why there is no need of any tint control with PAL TV systems.
With the help of a 1H delay line that produces lower saturation, the chrominance phase errors that may occur in the PAL system are cancelled out. This is in turn very much less noticeable to the eye than the hue errors you find in NTSC systems.
There is a small drawback in PAL TV systems where the alternation of color information through Hanover bars can at times lead to picture grain on pictures having extreme phase errors. Sometimes even the mis-alignment of decoder circuits or the use of simplified decoders of early designs in the PAL TV system may lead to picture on grain on pictures.
However such extreme phase shifts do not occur much. The effect is usually observed when the transmission path is poor, if the terrain is an unfavorable one or in typically built up areas. It has been noted that the effects are more noticeable on UHF signals than on VHF signals. This is because VHF signals are generally more robust.
The greatest advantage of the PAL TV system over the NTSC system is that it avoids the NTSC system’s sensitivity to phase changes through minor modifications where high color fidelity is achieved. With the help of a delay line and two adders, the PAL decoder adds color signals of successive lines while canceling out phase errors. The delay line here works as a line storage device.
Today, the PAL TV system is the most common and prevalent television system found in more than 65 countries because of it excellent color stability. There are different brands of PAL TV systems available today; it is up to you to choose the best brand and model you want depending on your budget and your entertainment requirements.
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