Analog
The technology in use for more than 50 years to transmit conventional radio and TV signals. Vinyl recordings and motion picture films are examples of analog technology.

Aspect ratio
The ratio of television picture width to height no matter the size of the screen. Since the 1940s TV’s have used a 4:3 screen. Most new digital TVs will use a widescreen which is 16:9. This is much more like you experience at a movie.

ATSC
An acronym for Advanced Television Systems Committee, and the name of the DTV system used by broadcasters in the U.S. In European they use the COFDM standard. A digital tuner made for use in Europe can not be used in the US and visa versa.

Bandwidth
The amount of spectrum available to each communications licensee. For digital conversion, the FCC has allocated 6 MHz (megahertz) of UHF bandwidth ( a channel) for each broadcaster. This amount of bandwidth can carry up four or more multicast digital signals, a high-definition signal, data, or a combination of these elements.

Barn doors
A term used in television production to describe the effect that occurs when a 4:3 image is viewed on a 16:9 screen. Viewers see black bars ("barn doors") on the sides of the screen. cf. Letterbox & aspect ratio.

Cliff effect
A characteristic that causes DTV reception to deteriorate dramatically with a small change in signal reception. Unlike analog television where the picture gets ”snowey” and gradually disappears, a Digital picture will be prefect one minute, and lost entirely the next.

Codec
Short for "coder-decoder". A device that converts analog video and audio signals into a digital format for transmission. It also converts received digital signals back into an analog format.

COFDM
Acronym for "Coded Orthogonal Frequency Division Mulitiplexing," the DTV standard used in Europe (akin to ATSC in the U.S.).

Compression
The process of fitting a large file into a space that is many times smaller. In the case of video, the method used for the DTV standard is MPEG-2, which can take four full-range channels of programming and data and compress them into the same space currently occupied by a single analog channel.

Computer Input
Some HDTV sets have an input (typically SVGA or VGA) that allows the TV set to be connected to a computer.

Convergence
Convergence occurs when two previously independent entities become one. In Digital Television, convergence refers to the integration, blending or merging or television and computer technology. For example, you can now watch on your television video you stream or play from your computer.

Datacasting
Digital television allows for the transmission of not only digital sound and images, but also digital data (text, graphics, maps, services, etc.). This aspect of DTV is the least developed; but soon, applications will likely include interactive program guides, sports statistics, stock quotes, retail ordering information, and the like. Datacasting is not two- way, but using it in combination with a simple dial-up modem, simple responses placing orders for products or answering viewer polls will be possible.

DBS (Direct Broadcast via Satellite)
Subscribers receive programs via a small satellite dish. The signal is digitized and compressed via a proprietary format and decompressed by a set-top box. In most cases it is viewed on a analog TV. Some DBS companies are beginning to offer DTV and HDTV content. To receive these services you must have a special receiver and DTV set.

Digital cable
A service provided by many cable providers (Time Warner and InSight both offer it) which offers viewers more channels, access to pay-per-view programs, and online guides. Digital cable is not the same as HDTV or DTV; rather, digital cable simply offers cable subscribers the better picture quality and additional services. In the Cincinnati area, Time Warner offers an HDTV digital set top box that allows you to connect a HDTV set to the cable and receive some HDTV programming. You will find WCET Digital on TW Channel 948.

Digital Television (DTV)
Transmitting a broadcast signal by encoding it as 0s and 1s the digital code used in computers. DTV can be compressed to provide four, five, or more channels in the same bandwidth required for one channel of the current standard television, better sound, and about five times more picture information (picture elements, or pixels) than conventional television. WCET uses a different channel, i.e Channel 34, to transmit this service.

Digital tuner or digital receiver
A digital tuner serves as the decoder required to receive and display digital broadcasts. Some digital tuners can convert broadcasts for an analog TV or provide a digital signal to a digital television. It can be included inside TV sets or via a set-top box. If you convert the digital signal to be viewed on a analog set, you will not get the better picture quality nor widescreen format.

Dolby Digital
The approved 5.1-channel (surround-sound) audio standard for digital television. Six distinct audio channels are used: left, center, right, left rear, right rear (indicated by the "5"), and a subwoofer (indicated by the ".1").

Dolby Surround
Or Dolby Stereo. Four audio channels (left, center, right, and surround) converted to two channels referred to as right-total and left-total.

Downconverting
Process by which a high-definition signal is converted to a standard definition picture.

DVD
"Digital Versatile Disc" (Formerly Digital Video Disc.) Same size as a CD but stores seven times CD capacity on a single side.. Today most DVDs are used to display full-length motion pictures, plus additional material such as out takes, director's notes, movie trailers, etc. WCET uses this technology to distribute educational materials to schools.

Electronic programming guide (EPG)
An application that provides an on-screen listing of all programming and content that a DTV viewer has available.

Enhanced TV
Or enhanced digital television (EDTV) (also known as datacasting). A term used for certain digital on-air programming (not generally available today) that includes additional resources viewers can download. Viewers will be able to simultaneously watch an enhanced TV production and, in the background, receive hundreds of megabytes of additional video, audio, text, and images related to the program. Imagine your favorite PBS documentary accompanied by a CD-ROM, but with the content stored directly on your computer or in the memory of your digital set-top box.

FCC
The Federal Communications Commission; the body that governs, among other things, radio and television broadcasting in the U.S.

Fire Wire
A low-cost digital interface originated by Apple. It can transport data at very high speeds. It is widely viewed as one key solution to connect digital-related TV components with each other. Also known as IEEE-1394.

High-definition television (HDTV)
A digital television format that provides high-quality widescreen pictures with compact disc-quality surround sound. The aspect ratio of HDTV pictures is 16:9 as opposed to today''s 4:3 format. This is the most superior video picture available in digital TV.

Interactive television (ITV)
TV programming that features interactive content and enhancements, blending traditional TV viewing with the interactivity of a personal computer (not widely available at this time).

Interlaced scan
The means by which traditional television picture tubes create images on screen. An interlaced-scanning tube sends information to each pixel in the even-numbered rows of pixels on a screen, left to right and then top to bottom. Then it sends information to odd-numbered rows. This results in a slightly distorted picture, as the component parts of the image do not all appear on the television screen at exactly the same time. The 1080i (interlaced) high definition standard is an interlaced-scanning standard.

Letterbox
Refers to the image of a widescreen picture on a standard 4:3 aspect ratio television screen, typically with black bars above and below. It is used to maintain the aspect ratio of the original source (usually a theatrical motion picture of 16:9 aspect ratio or wider).

MPEG-2
Compression standards for moving images and audio set by the Motion Pictures Expert Group (MPEG), an international committee of industry experts. MPEG-2 is the basis for digital television transmissions in the U.S.

Multicasting
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. For example, WCET will soon multicasts programming on channel 34. Viewers in that service area with digital sets simply tune to channel 34 and then choose among four different services: 34-1, 34-2, 34-3, or 34-4.

NTSC
National Television Systems Committee; the industry group that set the analog television standard 50 years ago. The abbreviation NTSC is also used to refer to the current analog standard.

PAL
Phase Alternation Line (PAL) is the analog television display standard that is used in Europe and certain other parts of the world. The U.S. uses the American National Television Systems Committee (NTSC) standard.

Pixel
A combination of the words ""picture"" and "element " A pixel is the smallest discernible sample of video information, the "little squares" that make up an overall picture. pixels per inch (PPI) the measure of the sharpness (that is, the density of illuminated points) on a television display screen. A rule of thumb…the more pixels per square inch the better the picture.

Progressive scan
The means by which the picture tubes of computer monitors and newer televisions display images. The process uses a progressive scanning tube to send information to each pixel on a screen sequentially left to right, top to bottom to create the image.

PSIP
Pronounced "P-SIP" - "Program and system information protocol." A part of the digital system that enables a DTV receiver to identify program information provided by content providers and use it to create sophisticated electronic program guides.

Resolution
The amount of data used to make up a picture, screen, or audio track. The more data in a picture, the richer the image and the higher the resolution. Resolution is measured in a number of ways, depending upon the medium used. For example, digital TVs describe their resolutions in terms of the number of pixels or dots that make up the picture along the vertical and horizontal axes. One of the high-definition picture formats is composed of 1080 active lines, and each line is composed of 1920 active pixels. Therefore, each frame has more than 2 million (1080 X 1920 = 2,073,600) color pixels creating the image. By way of contrast, today''s typical analog television is roughly equivalent to 480 active lines, with each line holding about 440 pixels. So, each frame has slightly more than 200,000 color pixels in use creating the image.

Set-top box (STB)
Or set-top converter box. 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 downconverted; for digital-ready TVs, the digital signal will be passed directly to the television.

Simulcast
The broadcast of programming over two separate channels or forms of media at the same time. For example, during the transition period (at least through 2006), WCET will often simulcast Channel 48 programming on Channel 34. Of course if the program is in HDTV, the Channel 34 program content will be the same but the picture and sound of much higher quality.

Standard-definition TV (SDTV)
SDTV typically produces a digital image of a quality somewhat like that of digital cable.

Terrestrial broadcasting
A broadcast signal transmitted "over-the-air" from a ground-based transmitter to an antenna.

Upconverting
Process by which a standard-definition picture is changed to a simulated high definition picture.

Widescreen
A term given to picture displays with a wider aspect ratio than your standard analog TV. Digital HDTV or SDTV is referred to as "16:9 widescreen." Most motion pictures also have a 16:9 widescreen aspect ratio. Most digital TVs have screens wider than they are tall (for every 9 vertical inches, a DTV screen is 16 inches wide).