| What is digital television (DTV)?
The analog picture viewers currently receive is based on an analog transmission system (NTSC) which is more than 50 years old, and relies on a system of varying voltages to transmit a television picture. In December 1996 the Federal Communications Commission approved the US standard for a new era of television - "digital television (DTV)," a general term covering any kind of digital broadcasting. In a digital system, images and sound are processed using the same digital code found in computers: converting each element in a complete video picture to a binary code composed of 1s and 0s. The result is a picture with much sharper detail and better color than the analog standards in current use.
The digital revolution not only dramatically improves the quality of the television picture, but also makes possible the over-the-air delivery of several simultaneous services to viewers. These include the three main services of high definition television, multicasting in standard definition television and data transmission.
What is high definition television (HDTV)?
Digital television allows stations to broadcast programs in much higher resolution or clarity than standard analog television. This is called high definition television or HDTV. Viewers at home are able to receive high-quality, crystal-clear pictures. These visually stunning pictures, with more than twice the resolution and clarity of standard television, are displayed in a wide screen format with a 16:9 width to height ratio compared to analog's 4:3, or almost square format. And because HDTV is digital, audiences have the benefit of six-channel CD-quality "surround sound." In other words, viewers are able to enjoy a true home theater experience. HDTV normally provides 720 or 1080 lines of resolution (depending on format) vs. 480 lines on standard definition.
Will consumers be able to watch digital television on their existing sets?
Only if they have a digital receiver, and a good analog signal from their antenna. DTV information is encoded in a different way from the analog television signal and therefore needs a different kind of receiver. Manufacturers have developed converter boxes that will allow viewers to receive DTV channels and feed the signal out to their analog TV sets. However, although the digital converter box will allow you to receive a picture, it won't display the quality of HD.
Why does digital technology change the shape of the picture?
What's with those black stripes on my analog TV?
Why do we end up with Letterbox format?
The original 4:3 picture ratio was established to cloesely match the ratio used in film at the time. The new 16:9 ratio closely matches motion picture standards today. The letterbox format which is showing up on analog sets more and more allows viewers to see the entire production in 16:9 ratio, without losing nearly a third of the movie to cropping or pan & scan techniques. In other words, you're seeing the show as the producer/director created it, not reformatted to fit the nearly square 4:3 ratio of analog sets.
Will you be able to watch your existing VHS or DVD collection (in a 4:3 ratio) on a new digital TV? Most digital sets have an analog input that will allow you to hook up your existing DVD or VHS player. However, the picture quality will not be any better than that of a high quality standard television monitor.