By: Jo Chew
There are a few different television standards used worldwide today. Different standards are used in different countries and continents. CCIR/PAL is used throughout most of Europe, Australia, New Zealand, most of Africa and Asia.
A similar concept is used in the EIA/NTSC recommendations for the television used in the USA, Japan and Canada.
There is also SECAM which is used in France, Russia and some other Eastern European countries.
The major difference between these standards is in the number of scanning lines and frame frequency.
CCIR stands for Comittee Consultatif International Radiotelecommunique. This is the committee that recommended the standards for B/W television accepted by most of Europe, Australia and others. This is why when we refer to equipment that complies with the B/W TV standards we call it CCIR compatible. The same "type" of standard, but later extended to colour signals, was called PAL. The name comes from the concept used for the colour reproduction by alternate phase changes of the colour carrier at each new line, hence: Phase Alternate Line-PAL.
EIA stands for Electronics Industry Association, an association that created the standard for B/W television in the USA, Canada and Japan, where it is often referred to as RS-170, it being the recommendation code of the EIA proposal. When B/W TV was upgraded to colour, it was named by the group that created the recommendation: National Television Systems Committee, or abbreviated NTSC.
SECAM comes from the French "Sequentiel a memoire" which actually describes how the colour is transmitted, by a sequence of chrominance colour signals and the need for a memory device in the TV receiver when decoding the colour information.
All of the TV standards use the picture ratio of 4:3 (4 units in width, 3 units in height). This is mostly due to the similar film aspect ratio of the early days of television.
The different number of lines used in different TV standards dictates the other characteristics of the system. CCIR recommends 625 lines, EIA 525 lines and SECAM 819 lines.
Irrespective of these differences, all of the systems use the same concept of composing pictures with electron beam scanning lines, one after another.