Analog technology has been in use for the past 50 years to transmit TV signals to consumers. Traditional television broadcasts analog signals. Vinyl recordings and motion picture films are examples of analog technology.
A numerical expression of the relationship of width to height of a TV screen. The National Television Systems Committee (NTSC) TV screen has a 4:3 aspect ratio. Regardless of the actual size of the screen, proportionally “4” units of width will correspond to “3” units of height. Digital television formats, including all high definition (HDTV) and some standard definition (SDTV), have a 16:9 aspect ratio. Wide screen 16:9 programs provide a viewing experience very similar to that of motion pictures.
A term used in television production to describe the effect that occurs when a 4:3 image is viewed on a 16:9 screen. When this happens, viewers can see black bars on the sides of screen or “barn doors.”
This term is short for “code-decode.” A codec is a digital signal processing unit that converts an analog input on the sending end to a proprietary digital signal for transmission and reverses the process on the receiving end outputting an analog signal identical to the input signal.
Compression refers to the reduction of the size of digital data files by removing redundant and/or non-critical information so that the original signal occupies less space in the transmission channel or storage device.
Some HDTV sets have inputs such as SVGA or VGA that allows the TV sets to be connected directly to computers.
The transmission of program data such as text, graphics, maps, services, etc., along with the broadcast program. This permits viewers to download this data to specially equipped computers, cache boxes, set-top boxes or DTV receivers. Datacasting will make possible the delivery of in-depth information to your PC or your digital TV while you are watching a program.
A device or program that translates encoded data into its original format.
A service provided by many cable systems utilizing digital transmission with distribution networks. Because more information can be delivered in a digital format, digital cable offers viewers more channels. Contrary to many consumers' beliefs, digital cable is not the same as high definition television.
DTV monitors display a digital input signal but lack an integrated tuner and thus cannot receive a digital broadcast signal, either over the air or via cable, without an additional set-top box.
Digital TV is the umbrella term encompassing all audio and video transmission utilizing digital data streams. Digital television could be said to include high definition television, standard definition television and other applications, including datacasting, multicasting and interactivity. DTV can be compressed to provide multiple channels in the same bandwidth required for just one analog channel, as well as better sound and about five times more picture information.
A digital tuner serves as the decoder required to receive and display digital broadcasts, either over the air or via cable. It can be incorporated into a television set or in a separate set-top box. Also referred to as a Digital Receiver.
Process by which a high definition signal is converted to a standard definition picture.
High Definition Television (HDTV)
A digital television format that provides high-quality widescreen pictures with compact disc-quality surround sound. This refers to the best picture available via digital television.
This is when television programs feature interactive content and enhancements, blending traditional TV viewing with the interactivity of a personal computer.
Letterbox refers to the image of a wide-screen picture on a television screen, typically with black bars above and below.
The ability to send more than one program or data service within the allotted channel spectrum. Digital channels can squeeze up to four channels into their spectrum.
NTSC is the acronym for National Television Systems Committee, which developed the current analog color television transmission standard adopted for use in the United States by the FCC in 1953.
Pixel a combination of the words “picture and element.” A pixel is the smallest element of raster display, i.e., a picture cell with specific color and/or brightness.
Pixels per Inch
Pixels per inch (PPI) is a measure of the sharpness of a television display screen.
The ability of an optical or video system to produce separate images of objects very close together, hence reproducing fine picture detail.
The process by which analog signals are measured and converted into a digital number. Sampling occurs millions of times per second in order to convert analog video into digital video.
Set-top Converter Box (STB)
Any one of a number of local user boxes designed to either convert digital signals to analog format or to manipulate any of the various digital transmission formats into a standard viewable on a DTV monitor. This device accompanies the viewer's TV, receives the digital TV signal and then sends that signal to the television. For analog TVs, the signal will first be down-converted; for digital-ready TVs, the digital signal will be passed directly to the television.
“Super Video Graphics Array” display mode. A higher-resolution version of the dominant video standard for PC graphics developed by IBM. Common SVGA resolutions are 800Vx600H with up to 24 bits used to describe the color of each pixel.
System of transmitting electrical signals for the reproduction of pictures or sound over-the-air, point to multi-point, received by a local user via antenna. Often synonymous with the concept of “free TV” and radio.
Process by which a standard definition picture is changed into a simulated high-definition picture.
“Video Graphics Array” display mode. Dominant video standard for PC graphics developed by IBM. VGA modes are 640Vx480H pixels at 4 bits per pixel, or 320Vx200H pixels where 8 bits are used to describe a pixel.
A term given to picture displays with a wider aspect ratio than your standard analog TV. While watching a program produced in the wide screen format, viewers see a more horizontal picture. The wide-screen picture format is intended to provide a more realistic and compelling visual presentation. A wide-screen display is commonly referred to as a "16 x 9" format.