HDTV Glossary

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Digital Television (DTV)
Refers to all formats of digital television, including high definition television (HDTV), and standard definition television (SDTV), which is also referred to as ATV (advanced TV). DTV is the transmission, reception and display of pure digital signals on a digital TV set. The digital signals can be broadcast over the air for free, or transmitted by a cable or satellite system to your home with a subscription. Stations choose which formats to broadcast. In your home, the decoder (located inside the TV or in a set-top box) receives the signal and directly drives your digital TV set.

Digital TV Formats

  • Six HDTV formats: Five progressive scanning (720p - 1280x720 pixels progressive) and one interlaced scanning (1080i - 1920x1080 pixels interlaced).
  • Eight SDTV formats: four wide-screen formats with 16:9 aspect ratios
  • Four video graphics array (VGA) formats

Digital Velocity Modulated Scan (Selectable)
Advanced circuitry along the neck of the CRT senses transitions from black to white in the video signal. The black and white portions of the signal are sped up and slowed down, respectively, resulting in sharp black-to-white transitions. For a more film-like picture when watching movies, you may want to selectively turn off this circuitry.

Dolby®
A compression/expansion (companding) noise reduction system developed by Ray Dolby, widely used in consumer, professional and broadcast audio applications. Signal-to-noise ratio improvement is accomplished by processing a signal before recording and reverse-processing the signal upon playback.

Dolby® Digital (AC-3)
Delivers CD-quality digital audio and provides five full-bandwidth channels for front left, front right, center, surround left and surround right speakers, plus an LFE (low frequency effect) subwoofer, for a total of 5.1 channels.

Dolby® Digital Surround
Perceptual encoding data reduction system that provides 5 discreet full range (20-20khz) channels (L-C-R-LS-RS) and a dedicated low frequency effects channel replicates the Theater experience in the home. (Dolby® Digital 5.1 channel surround sound is the audio standard for HDTV. This provides audio channels for the front speakers (left, center, right); 2 channels for the rear surround sound and one channel for the subwoofer sound. You need a TV or an external audio system which is capable of AC-3 to get the full effect.

Dolby® Pro Logic™
Four channel audio system including Left, Right, Center and Surround. Utilizes active signal decoding to localize the position audio images within the sound stage. Differentiated from Dolby® Surround by the addition of center channel information and active signal processing.

Dolby® Surround Sound
Left and Right Rear Channel information is decoded and processed following specific delay and frequency response parameters to provide a dramatic environment of sound that envelopes you from all directions.

Downconvert
A term used to describe the format conversion from a higher resolution input signal number to a lower display number, such as 1080i input to 480i display.

DTS® (Digital Theater Systems, Inc.)
DTS is a worldwide brand name that is synonymous with high quality digital sound. Digital Theater Systems, Inc. develops, markets and licenses a range of proprietary digital audio technologies, products and content for the motion picture and consumer markets. DTS developed discrete 5.1 channel surround systems similar to but not the same as Dolby® Digital. (www.dtstech.com).

DTS-ES® Discrete 6.1
A true 6.1-channel format, as the back surround audio channel is discretely encoded into the DTS bitstream. This format offers better spatialization over the surround channels for complete 360-degree sound localization and surround pans (i.e., movement of sound in the surround channels from one side to another). A data flag signals the decoder (usually part of the receiver or pre-amplifier) that the bitstream contains an extra discrete back surround channel. For backwards compatibility, DTS-ES Discrete 6.1 back surround channel is ignored by DTS 5.1 equipment.

HD Ready-TV (High Definition-Ready Televisions)
Requires the addition of an external tuner/decoder (set-top box) to receive digital broadcasts. In an HD-Ready set, you buy the HD tuner separately.

  • Benefit: This approach keeps your initial cost down and lets you upgrade to HDTV when there is a more plentiful supply of programming. Your HD Ready set will still offer a dramatically improved picture and allow you to enjoy a superior digital picture when using a DVD.

HDTV (High Definition Television)
High-resolution digital television (DTV) combined with Digital Surround sound (AC-3). The resolution is up to 1080i scanning lines (interlaced) or 720 p. Digital 5.1 channel surround sound is the audio standard (AC-3). HDTV sets come in two forms:

  • HDTV sets: receiver/decoder is built in.
    Benefit: A higher screen resolution means a crisper, clearer picture. This combination creates a stunning image with stunning sound.
  • HD-Ready sets: require the addition of an external receiver/decoder (set-top box) to receive digital broadcasts. In an HD-Ready set, you buy the HD receiver separately.
    Benefit: This approach keeps your initial cost down and lets you upgrade to HDTV when there is a more plentiful supply of programming. Your HD Ready set will still offer a dramatically improved picture and allow you to enjoy a superior digital picture when using a DVD.

Interlaced Scanning
In a television display, interlaced scanning refers to the process of re-assembling a picture from a series of electrical (video) signals. The "standard" NTSC system uses 525 scanning lines to create a picture (frame). The frame/picture is made up of two fields: The first field has 262.5 odd lines (1,3,5...) and the second field has 262.5 even lines (2,4,6...). The odd lines are scanned (or painted on the screen) in 1/60th of a second and the even lines follow in the next 1/60th of a second. This presents an entire frame/picture of 525 lines in 1/30th of a second.
See also Progressive Scanning.

Invar Shadow Mask
Most picture tubes use standard shadow masks made of steel, which can expand under intense heat. Expansion of the shadow mask causes picture discoloration, often called "doming." But Invar shadow masks are made of a compound of iron and nickel, rendering them extremely heat-resistant.

  • Benefit: This high thermal tolerance eliminates doming and allows the tube to operate at a higher voltage, producing brighter whites, higher contrast, and purer colors.





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