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DIGITAL TELEVISION: Seeing is Believing

The revolution is being televised and in some parts of the country it can come to you tonight.

by George O. Roberts, Jr., Sharp Electronics

The Federal Communication Commission (FCC) has begun the digital revolution for television. Digital Television (DTV) is an exciting new broadcast standard that provides vastly improved picture and sound quality when compared to the current NTSC broadcast standard. With DTV, viewers can see images up to six times the resolution of their current TV’s. The received DTV image can be viewed without double image ghosts or snow frequently associated with some of today’s air/cable broadcasts. And wide screen movies can be displayed just like in the movie theater accompanied by a Dolby Digital (6-channel audio) soundtrack. The advent of DTV is one of the many advances in our industry that is an example of digital technology providing a higher quality product to today’s consumer.

Today, there are 18 approved DTV transmission formats.

The 1080i transmission (1,080 x 1,920 lines, interlaced) represents the highest level of digital broadcast. In the digital world, resolution is expressed in pixels per second. Also, there are two scanning methods used to receive the signal—interlaced scanning and progressive scanning.

An interlaced picture is constructed by interlacing two fields of video information to form one frame, as in today’s analog televisions. Wow! Is this complicated enough? In other words, two dots have a relay race across the picture tube of your television. One dot races across the set in 1/60 of a second. The first dot "tags" the second dot to race back in 1/60 of a second. When both dots have finished the race, you receive a full video frame. With progressive scanning, the picture is constructed of a single frame of video that encompasses all of the video information. Progressive scanning is done just like today’s PC monitors. When comparing resolution at any of the transmission levels, the difference is expressed in pixels per second:

1080i…one million pixels per 1/60 second.
480p…1/2 million pixels per 1/60 second.
480i…1/4 million pixels per 1/60 second.

The first digital broadcasts were targeted for broadcast in November, 1998, in ten major U.S. cities: Atlanta, Boston, Chicago, Dallas, Detroit, Los Angeles, New York, Philadelphia, San Francisco, and Washington, D.C. (Unfortunately, Chicago and New York experienced delays and moved further down the schedule.) These cities, and the rest of the country, will experience a gradual transition from the current analog broadcasts to digital broadcasts over the next ten years. Because the digital broadcast is over-the-air, consumers will be able to pick up the signal with an in-home antenna, or in the same manner they currently use. Also, cable and satellite companies will be able to transmit a digital signal. Subscription rates and types of programming will vary. However, access to a digital signal will be relatively easy once a broadcast begins in your area.

Do I need to wait to buy a digital television?

No. When your town/city starts to broadcast a digital signal, the television components in your house will have to be updated. That means you will need a decoder to decode the digital transmission to receive a digital signal. The local broadcaster in your area may choose to broadcast any one of the 18 approved signals or may even choose to utilize multiple transmission broadcasts. But don’t worry about your current television set becoming obsolete. If you would like to see a digital broadcast, purchase a digital decoder and view the programs you desire. And remember the FCC will continue to offer analog broadcast space for television programming at least until the year 2006. So, you will be able to watch all your favorite shows just the way you are now, or you can choose to update to digital technology when you desire.

One aspect of digital television is the ability to receive the signal. The other important aspect of digital television will be the ability to receive audio and video signals at a far higher quality than ever before. The digital television signal has two different formats: HDTV (High Definition Television) and SDTV (Standard Definition Television). HDTV transmissions are at 1080i or 720p. SDTV broadcasts are any of the other digital transmission rates. HDTV broadcasts are at the top end of the digital television spectrum. These broadcasts will have the best sound quality, the ability to broadcast in a wide screen format, and the best picture quality. The picture quality of HDTV is exceptional. The colors are brilliant. The depth of the image is almost three-dimensional. Many people viewing HDTV for the first time have commented that, "it’s almost like being there." In order to experience the high-quality picture of HDTV, you will need more than a digital decoder. You will need a television monitor/receiver capable of receiving video information at levels significantly higher than most of today’s current line-up of NTSC television sets. Sharp showed prototypes of these models at the Consumer Electronics Show. Remember, the resolution of HDTV will be six times the resolution of today’s NTSC televisions. Therefore, part of this digital revolution will be for manufacturers to produce television components capable of producing the high quality video images that will be broadcast.

The reaction to Sharp’s proposed digital television products has been extremely favorable. It is guaranteed that the DTV revolution will be an exciting consumer event. It will be a technological marvel and a visual showcase that will provide the viewer with a more accurate, more consistent, more enjoyable way of receiving video information than ever before. Indeed, the digital television revolution will be televised. It will be LIVE.

Copyright 1998 Sharp Electronics, Inc. Used with permission.

 

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