Zenith Plasma TV and Flat Panel Monitor

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DTV Explained By Zenith

Analog Television
The analog television broadcast system used in the United States for the past 50 years transmits signals as an electronic wave. In the wave, images and sounds are represented by continuously changing frequencies and voltage levels. Transmitters broadcast this signal over the air, and the waves are translated back into images and sounds by TV sets. Unfortunately, the shape of this wave is susceptible to degradation as it travels to your home. This degradation can introduce unwanted elements, called artifacts, into the picture. Many things can interfere with an analog signal, such as planes passing overhead and household appliances.

Digital Television
When a digital television signal is transmitted, images and sounds are divided into tiny components of computer information, the ones and zeros of computer language. The computer data provides a more consistent signal that is highly resistant to interference. Unlike the analog wave, there is no chance of misinterpreting what the computer data means. Digital television sets can then receive this data and decode it back into images and sounds. The result is a perfect, studio-quality picture free from the interference, snow and ghosts that appear on analog TV broadcasts.

Advantages of Digital Television

• Picture
  Pictures add realism to the television experience and crisp digital pictures are one of the biggest advantages of digital television. Unlike analog TV, digital TV is free from snow, ghosts and interference. What's more, with HDTV or high-definition television, the highest form of digital television, you get 4 to 5 times more picture information than conventional TV pictures. Combine that with the new widescreen format, and you have the ultimate home theater viewing experience.

• Sound
  Sound adds emotion to the television experience and digital television is enhanced with CD-quality theater-like audio. The digital television signal includes audio in the 5.1 channel Dolby Digital format — separate left and right front channels, left and right rear channels, center and subwoofer channels.

• Multicasting and Datacasting
  Digital broadcasts can carry huge amounts of digital information — more than 19 megabits per second. Because of this, a broadcaster may choose to split their channel into two or more streams of programming to offer more choice and flexibility to the viewer.
      Multicasting allows a broadcaster to transmit several standard-definition digital programs at the same time. For example, a broadcaster may show a high-definition movie, a popular sitcom and a news program all at the same time.
      Datacasting links information from various sources, such as the Internet, to the television broadcast and allows the information to be displayed on-screen at the same time as a television program or delivered to your PC. You will then be able to get the latest stock quotes, access statistics on your favorite player during a football game, or order the product you just saw advertised right from your TV.

Digital Video Formats
The Advanced Television Systems Committee (ATSC) digital TV standard adopted by the FCC in 1996 contains 18 scanning formats. They include interlaced and progressive scan HDTV and SDTV formats with varying frame rates, and two aspect ratios.

• Active Lines
  Scanning formats are measured in active lines of picture elements or pixels transmitted, both horizontal and vertical. The number of total pixels is calculated by multiplying the amount of vertical lines by the density of horizontal picture elements. For example, the 1920x1080 HDTV format has more than 2 million pixels. (1920 X 1080 = 2,073,600). Today's NTSC video only has a resolution of 211,200 pixels (480 vertical lines and 440 horizontal pixels).

• Aspect Ratio
  The aspect ratio refers to the shape of the video image. Today's television has a 4:3 aspect ratio, which is almost square in appearance. Digital television will have either a 4:3 or 16:9 aspect ratio. A 16:9 aspect ratio is widescreen, and appears rectangular: this looks more like a movie screen, filling more of the viewer's field of vision for a more lifelike vieweing experience.

• Scanning Method
  Frames of video are made up of many lines of video that are scanned onto a television screen so closely they appear to be a solid picture. The scanning method can be either interlaced or progressive. Interlaced scanning (also used in today's analog TV), indicated by an "i" in the video format, fills in the odd number lines (1,3,5,7...) and then fills in the even number lines (2,4,6,8...) until the frame is complete. Progressive scanning, "p", fills in each line consecutively until the frame is complete, like a computer display.

• Frame Rate
  Frame rate, also known as picture rate, is the speed at which the lines are scanned in order to create a video frame, 60-, 30-, or 24-frames per second.