Understanding Tech
HDTV Glossary

Analog Television
Current system that uses magnetic waves to transmit pictures and sound. These broadcast signals create images by interlaced scanning lines (measures at 480i). Analog television is due to be converted to DTV (Digital Television) in December 2006. Most consumers will be able to view DTV on their analog televisions with the use of an inexpensive receiver to decode the broadcast signals.

Aspect Ratio
Describes the viewing area on a display in regards to its width in conjunction with its height. Full-screen displays have an aspect ratio of 4:3 and wide screen displays have an aspect ratio of 16:9.

The quality of color in reference to its hue and saturation. In a display, the picture chrominance can be adjusted to add grayness or color saturation to a picture. Video signals use chrominance combined with luminance to create picture quality.

Contrast Ratio
Measures to the difference between the lightest white point and darkest black point in a display. A higher contrast ratio shows more detail and gives an overall better quality picture.

Dolby Digital
Audio coding system created by Dolby Laboratories in the 1970s. Designed for multichannel audio output but will also support single (mono) audio channels. Full surround sound known as Dolby Digital 5.1 has five channels (left, right, center, left surround, right surround) plus a .1 low channel frequency for deep bass sound. Some HDTVs contain the programming to deliver Dolby Digital 5.1 using DTV with additional equipment.

Digital Television. A new broadcasting method using computer code to deliver a high quality picture and Dolby Digital sound. DTV is scheduled to go into effect nationally by late 2006. Older analog televisions will be able to translate DTV signals with a decoder, but not display as high definition without a HDTV compatible television.

DTV categories:

SDTV - Standard Definition Television. Television that receives analog broadcast signals, typically has an 4:3 aspect ratio, outputs non-Dolby Digital audio, and has a picture quality less than 480p or 480 progressively scanned lines.
EDTV - Enhanced Definition Television. Television that can receive digital television signals of at 480p or higher, have an 4:3 or 16:9 aspect ratio, and is capable of delivering Dolby Digital audio with HDTV compatible televisions.
HDTV - High Definition Television. See HDTV.

Television that has a picture quality of 720p to 1080i, has an 16:9 aspect ratio, is capable of delivering Dolby Digital audio.

HDTV terms:

HDTV-Ready/Monitor refers to a display that can transformed into a HDTV with a tuner or other hardware.

HDTV Tuner is a separate device that has the ability of receiving and outputting HDTV signals. This tuner may be also referred to as a decoder, receiver or set-top box.

Interlaced Scanning
Process used to create a television picture by alternating lines of information by scanning the odd-numbered lines first, then filling in with the even-numbered lines. The higher in number of interlacing creates a more detailed, better-quality picture. Interlaced scanning is used by all analog broadcast systems.

LCD or Liquid Crystal Display
A display engineered by compressing an electrically reactive, liquid crystal solution between two sheets of polarized material, then charging the solution by two electrodes. The current passes through the solution to activate the crystals in an aligned pattern.

Refers to the level of brightness in a display. A component of a video signal that works in conjunction with chrominance to control the quality of a display picture.

Plasma Display
Display that creates images by using phosphors that react to a plasma-state gas when electric current is passed through it. The picture is visible when a vertical and horizontal line intersects to make a pixel or point of light.

Progressive Scanning
Process of creating a picture by rapidly displaying all lines of a information simultaneously. This method is used by high definition digital signals and requires higher bandwidth than analog signals.

Measures picture quality of a display by the amount of pixels per inch. The higher in number the resolution (or pixels) is in a display, the better picture quality.

Video Interfaces

Composite Video - Analog video system that signals are combined into a single channel. Both the chrominance and luminance is transmitted together. Used for analog television signals and can be modulated onto an RF carrier.

S-Video – Super Video. Interface that separates the chrominance and luminance information for improved picture quality.
Component Video - A type of video system that transmits two or more separate signals such as separate color, RGB (red/green/blue), or separating chrominance and luminance. Because these signals are sent by multiple channels verses a single channel, the resulting picture quality is improved.
DVI - Digital Visual/Video Interface. A digital interface that can convert digital signals to analog to work between both digital and analog displays. DVI Types: DVI-A - analog only; DVI-D - digital only; and DVI-I - integrated analog and digital.
HDMI - High Definition Multimedia Interface. This interface delivers uncompressed digital audio/video signals and transmits information over one cable. HDMI Types: HDMI Type A - compatible with the single-link DVI and used by computer monitors, HDMI Type B - 29 pin connector for high bandwidth and compatible with dual-link DVI.

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