Televisions will be Around for Many Years

Televisions are evolving still. In the world of consumer electronics, there are very few products getting the face lift more than the television. From the ancient NTSC standard system, the television is getting a huge electronic upgrade into the exciting High Definition (HD) or ATSC (Advanced Television Systems Committee) system.
 

When will High Definition occur?

With over 50% of all television programs now available in high definition, it is estimated that by 2007, between 30% and 50% of all homes in the US will have own an HDTV. That means 50 million TV sets!

So, what is interlaced and what is progressive scanning? When the television was invented, the technicians couldn’t get the TV’s electron gun to scan the entire screen or field fast enough. So they ‘cheated’. The electron gun was made to scan every second line from the top to the bottom of the television screen until it reached the bottom, then return to the top to scan the opposite lines. As an example, it scanned the odd lines starting at 1, 3, 5, 7 etc and once finished, the even lines 2, 4, 6, 8 etc. The result of this interlaced scan was a flicker which was hard on the eyes. As the early TVs were smaller, it was difficult to notice. However, as the TVs got larger, people had to sit further back. Most regular TVs can scan no more than 540 lines interlaced, of DVD quality.

High definition TVs scan are capable of scanning progressively and at a higher field rate than the older television. Many HD TV sets can scan up to 1080i (interlaced) or 720p (progressive). Each television network has the freedom to choose the HD resolution and format (16:9 or 4:3), although many lower rated shows will broadcast at 500i or sometimes referred to as ED (extended definition) or SD (standard definition).

What is the optimum viewing distance per television screen size?

NTSC Analog 4:3 Aspect Ratio
27-inch: 8.0 feet
32-inch: 10.0 feet
36-inch: 11.0 feet
43-inch: 13.0 feet
50-inch: 15.0 feet
53-inch: 16.0 feet
61-inch: 18.0 feet

High Definition-Compatible 4:3 Aspect Ratio
32-inch: 5.0 feet
36-inch: 5.5 feet
43-inch: 6.0 feet
50-inch: 8.0 feet
53-inch: 8.0 feet
61-inch: 9.0 feet

High Definition-Compatible 16:9 Aspect Ratio
34-inch: 4.5 feet
42-inch: 5.0 feet
50-inch: 6.0 feet
57-inch: 7.0 feet
65-inch: 8.0 feet
 

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