Unit 21 Television Standards

Television Standards

There are three broadcast systems in the world and they are all different. The one that the UK uses is PAL, this broadcast system runs at 50hz which is 25 FPS (Frames per Second).  PAL is also a colour encoding system for analogue television used in broadcast television systems in most countries. In the 1950s, the Western European countries commenced planning to introduce colour television, and were faced with the problem that the NTSC standard demonstrated several weaknesses, including colour tone shifting under poor transmission conditions. 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 per second (50 hertz), and finding a way to eliminate the problems with NTSC. The resolution for PAL is 576i (PAL, 720 × 576 split into two interlaced fields of 288 lines). This is also the same for SECAM. 

SECAM 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, while PAL attempts to improve on the NTSC method.
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. Like PAL, a SECAM receiver needs a delay line, but unlike PAL, it is not possible to build a SECAM receiver without one.

NTSC was developed in 1940 by the United States Federal Communication Committee to resolve the conflicts that were made between companies over the introduction of a nationwide analog television system in the United States. in March 1941, the committee issued a technical standard for black and white television that built upon a 1936 recommendation made by the Radio Manufacturers Association. NTSC runs at 60hz which is 30 FPS. This gives the television a smoother image, this is better for sports because it doesn't make the movement have a blur. The resolution for NTSC is 480i (NTSC standard uses an analog system of 486i split into two interlaced fields of 243 lines).