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- 4 x 3: The aspect ratio of the TV screen, "4" units wide and "3" units high.
- 16 x 9: The aspect ratio of the TV screen, "16" units wide and "9" units high. This shape of screen is also referred to as “widescreen.”
- Aspect Ratio: The ratio of a television picture width to height.
- Bandwidth: The complete range of frequencies over which a television station is allowed to function. The U.S. analog and digital television channel bandwidth is 6 MHz.
- Closed Captioning: An optional display of an actor’s dialogue, actions, sounds, or other elements of the program as text on the screen.
- Compression: Reduction of the size of digital broadcast data files by removing redundant and/or non-critical information. Digital TV in the U.S. would not be possible without compression.
- Datacasting: The ability to broadcast data in addition to program material allowing viewers the ability to download data ( text, graphics, maps, services) to specially equipped computers, set-top boxes, or DTV receivers.
- DBS: "Direct broadcast satellite." An method of distributing subscription television services to consumers utilizing a fixed small format satellite dish.
- Dolby Digital (formerly Dolby AC-3): The approved 5.1 channel (surround-sound) audio standard for digital television.
- DTV: "Digital television." This includes all the components of digital television, HDTV, SDTV, datacasting, and multicasting.
- DVD: "Digital Versatile Disk." (Formerly Digital Video Disk.) An optical disc that can playback video on demand.
- Electronic Programming Guide (EPG): An on-screen listing of all programming and descriptive content for the viewer. EPGs are a feature of the new digital television sets as well as cable and satellite systems.
- HDTV: "High Definition Television." The highest quality picture available in DTV. In the U.S., the 1080i and 720p formats in a 16 x 9 aspect ratio are considered High Definition. HDTV is a component of DTV. Often described simply as “HD.”
- Letterbox: The format of a wide-screen picture when it appears on an analog 4 x 3 aspect ratio television screen, typically with black bars above and below. Used to maintain the original aspect ratio of the original source (usually a theatrical motion picture of 16 x 9 aspect ratio).
- Multicasting: Digital technology allows each digital broadcast station to split its bandwidth into 2, 3, 4 or more individual channels of programming and/or data services.
- NTSC: "National Television Systems Committee" and the name of the current analog transmission standard used in the U.S., created many decades ago.
- PSIP: Pronounced "P-SIP" - "Program and System Information Protocol." Data broadcast to digital television receivers that enable a DTV receiver to create on screen electronic program guides.
- Resolution: The higher the screen resolution, the more picture detail viewers will see. Many things affect resolution, including number of bits, pixel count, format, receiver quality, cameras, lenses and lighting used for live or taped programming, etc.
- SDTV: "Standard Definition Television." Digital formats that do not achieve the video quality of HD, but are at least equal, or superior to, analog pictures. SDTV may have either 4 x 3 or 16 x 9 aspect ratios, and it includes surround sound. Often described simply as “SD.”
- Set-top box (STB): Device that converts data from analog cable, digital cable, or digital broadcast television for display on a standard analog television set, or a box that receives off-air DTV signal for display on a DTV monitor.
- Simulcast: The broadcast of the same program simultaneously over two or more different systems or channels.
- Video-on-Demand (VOD): When video can be requested at any time, at the discretion of the viewer. This service is typically offered to cable customers or by many web sites.
- Widescreen: Term given to screens with a wider aspect ratio than 4 x 3. Digital HDTV is 16 x 9 widescreen. Most motion pictures also have a widescreen aspect ratio, some even wider than 16 x 9.
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