HDTV - High Definition Television

The Federal Communications Commission (FCC) has mandated that all stations be capable of broadcasting HDTV by 2006.

For more details click on a link below:

HDTV seems to be everywhere you look now. When you go to an electronics store, HDTV seems to be the buzz word. But what the heck is it? If you have ever looked at one of these TV sets you would see the unbelievable difference compared to your typical analog television. The picture quality and the shape of the screen resemble more of a movie format than television.

HDTV has lifelike pictures and digital sound. The higher resolution produces clarity like you don't see with an everyday picture tube television and the width of the screen allows better movie viewing and wider images shown.

Your typical TV is what we call analog television. In analog TV, a 6 MHz analog signal carries intensity and color information for each scan line of the picture. An analog TV signal in the U.S. has 525 scan lines for the image, and each image is refreshed every 30th of a second (half of the scan lines are painted every sixtieth of a second in what is called an interlaced display). The horizontal resolution is something like 500 dots for a color set. This level of resolution was amazing 50 years ago, but it has certainly gone it's course. Today's personal computer resolution far supercedes the resolution viewed on your analog television with many resolutions ranging from as small as 640x480 to the widely used resolutions of 800x600 and 1024x768, to many even higher.

Much of the new satellite TV systems as well as DVDs have the capabilities to deliver a much clearer image that HDTV could enhance for the viewer's pleasure. With analog television, these capabilities are stymied by the process that is created to accomodate analog television. Hence enhancement and quality are lost.

There is now a big push underway to convert all TV sets from analog to digital, so that digital signals drive your TV set directly. DTV (Digital television) was developed in conjunction with ATSC or the Advanced Television Systems Committee. This technology is capable of transmitting HDTV (High Definition Television) or SDTV (Standard Definition Television).

HDTV is the highest DTV resolution in the new set of standards. It offers beautiful vivid imaging with awesome Dolby Digital surround sound. HDTV requires television stations and broadcasters to acquire much new equipment for shooting, editing, and production, as well as new equipment needed for reception of this programming by the consumer. The higher resolution picture is the main selling point for HDTV. Imagine 720 or 1080 lines of resolution compared to the 525 lines people are used to in the United States.

Of the 18 DTV formats, six are HDTV formats, five of which are based on progressive scanning and one on interlaced scanning. Of the remaining formats, eight are SDTV (four wide-screen formats with 16:9 aspect ratios, and four conventional formats with 4:3 aspect ratios), and the remaining four are video graphics array (VGA) formats.

The formats used in HDTV are:

  • 720p - 1280x720 pixels progressive
  • 1080i - 1920x1080 pixels interlaced
  • 1080p - 1920x1080 pixels progressive

Interlaced- referring to the scanning system. Interlaced screen shows every odd line at one scan of the screen and then follows up with the even lines in the second scan. There are 30 frames shown per second, having the screen show 1/2 of the frame every sixtieth of a second. This isn't a problem with smaller televisions, but as the sets grow larger, the process is visually seen by the viewer as the flicker affect.

Progressive- this type of scanning shows the whole picture, every line in one showing, every sixtieth of a second. With this you get a smoother picture, but eating up more of the bandwidth.

The differences between analog television and HDTV are very obvious. First visible is the shape of the screen. HDTV screens are much wider. When an analog television picture screen's width is divided by it's heigth, you get a ratio of 4/3. An HDTV's heigth to width ration of 16/9, more closely resembling a movie screen.

The second difference is quality of image. The HDTV can deliver an image that has six times the clarity and the sharpness of analog television. It contains 1080 vertical pixels and 1920 horizontal pixels. This totals over 2 million pixels! The more pixels there are, the clearer the image. Same rule goes for an image viewed on your computer screen. Analog television is 480x720 pixels equalling 345,600. Not even close. Along with that comes six channels of Digital Dolby surround sound. And the final difference is that the signal is digitally transmitted doing away with snowy, fuzzy screens and double images. What you get is a picture perfect image, CD quality sound that is the same viewed 50 miles away from transmission as that viewed 1 mile away.

The differences are different for the television stations and broadcasters as well. To deal with HDTV's new standards, broadcasters will need to get all new equipment, such as cameras, remote broadcast units, control rooms, cables, and sound equipment. This is because digital TV has:

  • Wider images
  • Much more detailed pictures
  • 5.1 channel CD-quality Dolby Digital (AC-3) surround sound
  • The ability to send data directly to a screen or to a PC as a download (The actual HDTV transmission is based on a 19.3-Mbps digital data stream.)

The aspect ratio (width to height) of digital TV is 16:9 (1.78:1), which is closer to the ratios used in theatrical movies, typically 1.85:1 or 2.35:1. Currently broadcasters must either pan and scan the image (crop the full picture of the film down to 4:3, eliminating part of every scene in the process) or letterbox it (present the full picture only on the middle part of the screen, with black bars above and below it). With a 16:9 screen, panning and scanning a theatrical movie doesn't remove so much from the original picture and letterboxing doesn't block out so much of your screen.

Don't worry, your analog television hasn't become obsolete yet. You can still receive your current standard definition television transmission, however you cannot recieve the new digital high definition transmission. All you would get is snow, black and white spots.

To receive the digital high definition transmission, you must purchase a DTV reciever. This can be purchased at most electronics dealers in your area. With that you can receive the new transmission, as well as the old standard definition television transmission. The FCC is keeping a close eye on the purchase and sales of DTV recievers, monitoring every two years. If a significant progression is realized by the FCC and the vast majority of the public has converted to DTV, then analog television will be removed from the air waves. A target date is currenlty set for 2006. However many feel that this date most certainly will be pushed back for many years.

ch. 31
What is currently showing on 12WKRC HDTV?

The FCC has mandated that all stations be capable of broadcasting HDTV by 2006. With this, the federal government has loaned all existing broadcasters an additional television channel to broadcast HDTV to all capable viewers so as not to interrupt standard broadcast television.12WKRC-TV can be seen on it's standard channel 12 and our HDTV version can be seen on channel 31. Click here to see what's on 12WKRC-TV and HDTV today.

CBS has been producing its programs on 35mm for many years, unable to show them at the greatest quality possible with analog television. Eventually all programming and the CBS primetime schedule will be converted to HDTV. With HDTV this will allow us to deliver high quality image with excellent digital dolby sound providing the viewers with the finest quality product available.