What's Wrong with Analog TV?

The main problem is resolution.

• The resolution of the TV controls the crispness and detail in the picture you see.
• The resolution is determined by the number of pixels on the screen.
• An analog TV set can display 525 horizontal lines of resolution every thirtieth of a second. In reality, however, an analog TV displays half of those lines in a sixtieth of a second, and then displays the other half in the next sixtieth, so the whole frame is updated every thirtieth of a second. This process is called interlacing.

That has been fine for years. But now we have all become conditioned by computer monitors to be comfortable with much better resolution. The lowest-resolution computer monitor displays 640x480 pixels. Because of the interlacing, the effective resolution of a TV screen is perhaps 512x400 pixels -- for example, when an MSN TV (formerly WebTV) box tries to display Web pages on an analog TV display, it can display about 512x400 pixels.

So the worst computer monitors you can buy have more resolution than the best analog TV set; and the best computer monitors are able to display up to 10 times more pixels than that TV set. There is simply no comparison between a computer monitor and an analog TV in terms of detail, crispness, image stability and color. If you look at a computer monitor all day at work, and then go home and look at a TV set, the TV set can look very fuzzy.

The drive toward digital TV is fueled by the desire to give TV the same crispness and detail as a computer screen. If you have ever looked at a true digital TV signal displayed on a good digital TV set, you can certainly understand why -- the digital version of TV looks fantastic! There is no comparison. With 10 times more pixels on the screen, all displayed with digital precision, the picture is incredibly detailed and stable.

Seeing the Difference
It is hard to convey the difference between a DTV signal and an analog signal without an actual demonstration, but here is a static comparison that can help you understand the idea. Below is a picture of an odometer:

This is a nice, crisp picture. Let's assume that this picture is being displayed on a good digital TV so that this is what you actually see. The following photo shows you what you would see on an analog TV:

You can see that the analog TV picture is much fuzzier than the digital TV image. Look, for example, at the teeth on the gears. There is a significant difference in picture quality that is even more obvious when the image is moving. It is that quantitative difference that drives the interest in digital TV. And as if the incredible picture weren't enough, digital TV also offers much better sound.