C Terms

C: Abbreviation for Chrominance.

C-Band: A range of frequencies, 3.7 - 4.2 GHz, commonly used for sattelite communications.

C&ES: Customer and Engineering Services.

C/N: Carrier to noise ratio.

Calendaring: The process of highly polishing the outer face of recording tape to make it smooth and limit its friction content.

Capstan: Part of a tape recorders transport system. In conjunction with the pinch roller, pulls the tape through the machine.

Carbon Microphone: A high-impedance type of microphone found in telephone receivers.

Cardiod Microphone: A microphone sensitivity pattern which is not sensitive to sounds from one direction. This results in a heart shaped sensitivity pattern from which the name is derived.

Carrier/Carrier Wave: A continuous electromatic wave at a radio frequency that can be modulated by a signal to carry information through a transmission medium.

Cart Controller: The real-time controlling device for LMSª multi-cassette system components including; VTRs, matrix switcher, elevator mechanism, and the cassette console in accordance with instructions supplied by the application controller. The Cart Controller has two parts; SCC (Standard Cart Controller) and VCC (Versatile Cart Controller). The software for the cart controller is installed in it.

Cassette Console: Storage region of multi-cassette systems consisting of long-term storage bins, direct-access bins, input and output ports, and the elevator mechanism. This console is mechanically connected to the VTR console for cassette transfer using a cassette elevator.

CATV: Cable antenna television. Commonly used as meaning "cable TV". Cable, or cable TV are the preferred terms.

CAV: Constant Angular Velocity; a video disc format that spins at a constant speed and assigns a variable track length to each frame. The disc spins at a rate of 30 frames per second reproducing one frame every revolution. At this rate, access to individual frames can be instantly identified and retrieved. This is referred to as rapid random access which is a basic requirement of interactive video. (See CLV).

CBT: Computer based training.

CCD: A semiconductor device that can produce an electrical output analogous to the amount of light striking each of its elements. CCD sensors are used in both motion video and still video cameras.

CCIR-601: CCIR Recommendation 601, "Encoding Parameters of Digital Television for Studios," is a recommendation adopted in 1986 by the CCIR (Comite Consulatif International des Radio-communications) which concerned digital component video systems in the 525 and 625 line standards. The document specifies sampling rates for digital video.

CCITT: Consultative Committee on International Telegraphy and Telephony.

CCTV: Any form of television aside from network TV and cable TV that is locally originated and displayed. A TV transmission system using wires or microwaves to distribute signals to a closed group of users.

CCVE: Closed Circuit Video Equipment. The various equipment elements associated with a CCTV system including cameras, accessories, processing equipment, transmission equipment, output devices, and storage devices.

CDMA: Code Division Multiple Access. Media access contention scheme for use both over the air and over fixed transmission media.

CD-ROM Drive or Player: A device that retrieves data from a CD-ROM disc. Differs from a standard compact audio disc player by incorporating additional error correction circuitry. Some models lack the necessary D/A converter to play music from standard compact discs.

CD-ROM: Compact Disc-Read Only Memory. A 4.75-inch laser encoded optical memory storage medium with the same constant linear velocity (CLV) spiral format as compact audio discs and some videodiscs. CD-ROMs can hold about 550 megabytes of data (equivalent to 1500 floppy discs). CD-ROMs differ from regular prerecorded compact audio discs in the amount of additional error-correction information encoded. CD-ROMS primarily are used for large data and graphic files but can play back standard audio Compact Discs as well. CD-ROM is a non-recordable medium and its standard is accepted worldwide.

CD-I (Compact Disc - Interactive): A consumer format using the 4.75-inch CD disc standard. Developed by Phillips and Sony, CD-I supports limited animation and motion video, and will play back both the CD digital audio and CD-ROM data storage formats as well. CD-I is currently used primarily for games and entertainment-oriented media, but trainers are interested in its interactive potential.

CD ROM XA: Compact Disc-Read Only Memory eXtended Architecture. Developed by Sony and Phillips to enhance the capacity of CD-ROM. Allows for limited animation and expanded use of audio through digital compression techniques. Up to four channels of audio (one hour of audio total) can be included on the disc with graphics and data.

CDV (Compact Disc Video): Provides about 5-minutes of full-motion analog video with about 20 minutes of digital audio on one disc. It is gold in color, and the primary use at the moment is music videos, most of which have been pressed in Japan.

CD/DA: Compact Disc/ Digital Audio. The 1980s replacement of the record and can store up to 72-minutes of high-quality digital audio on a small 4.5 inch disc.

Channel: A frequency band for transmission of one electromagnetic signal. A radio frequency band or cable spectrum segment providing a single carrier for transmitting electrical signals such as TV, FM, or data.

Channel Capacity: The maximum number of TV channels which can be simultaneously carried on a given distribution system.

Chip: An integrated circuit in which all the components are microfabricated on a tiny piece of silicon or similar material.

Chorus Effect: Audio effect that makes one voice (or source) sound like many.

Chroma Key: A type of key where the hole-cutting information is derived from a color rather than from a video level. A common example of chroma key is when the weathercaster appears to be standing in front of a map. The map is an electronic signal, and the weathercaster is in fact standing in front of a solid blue or green screen. The Chroma Key process electronically subtracts the color from the foreground image, and replaces it with video from the background image to form a composite image.

Chroma Resolution: The amount of color detail available in a television system, separate from any brightness detail. In almost all television schemes, chroma resolution is lower than luminance resolution. This is not perceived by the viewer because the human eyeÕs ability to see chroma detail is significantly less than it is for luminance information. Horizontal chroma resolution is only about 12 percent of luminance resolution in NTSC. (See Resolution).

Chroma/Chrominance: The signals, used in image reproduction systems, that represent the color components of the image. A black-and-white image has a chrominance value of zero.

Clear Channel: A transmission path in which the full bandwidth is available to the user.

Clock: A timing source for charge transfer functions within CCD chips.

CLV (Constant Linear Velocity): The rotation technique used for compact discs and video disc players designed for the consumer market. The rotation speed changes depending on the location of the track being read to allow the track to pass the playback head at a constant rate. This allows for increased storage capacity on the disc but reduces the ability to access individual frames of information quickly or accurately. CLV videodiscs hold 60 minutes of video and audio per side but have limited interactivity (still frame, etc.). (See CAV).

Co-location: Location of two or more communications satellites in geostaionary orbits to allow signals to be received by a fixed earth station as if from one satellite.

Coax: Coaxial. A one conductor, one ground concentric cable which can carry a wide range of frequencies.

Code Generation: A clock that will put an identification time code onto the tape carrying picture and/or track information.

CODEC: Code/Decode. An encoder plus a decoder is an electronic device that compressed and decompresses digital signals. CODECs usually also perform A to D and D to A conversion.

CODEC Bandwidth: Video codecs are generally broken into two categories; low-bandwidth codecs that operate at 56 Kbps to 384 Kbps, and high-bandwidth codecs that operate at 384 Kbps to 1.544 Mbps (or higher). Economical low-bandwidth codecs are generally used for individual or small group applications. Larger group situations generally require a higher bandwidth codec to insure good picture quality.

CODEC Options: Codecs offer a variety of features and options that help to tailor a videoconferencing system to a particular application, such as separate graphics and user data channels, and picture-in-picture video processing.

Coercivity: The ability of a magnetic tape to retain information.

Color Bars: An electronically generated signal consisting of red, blue, green, yellow, cyan, and magenta, plus gray, black, and white set to standards established by the Society of Motion Picture and Television Engineers. Color Bars are used as a reference at the head end of a videotape recording. The playback machine is set up using color bars to ensure accurate color saturation and balance during playback.

Color Burst: A nine-cycle sample of the subcarrier signal inserted at the beginning of each horizontal line just after the horizontal sync pulse and used to ensure that colors maintain the correct phase relationship during each line.

Color Depth: The number of bits per pixel. One bit per pixel allows two colors (often black and white) to be displayed; two bits per pixel allow four colors; three bits allow eight colors; and in general, n bits allow 2n colors.

Color Difference Signals: Matrixed signals derived from subtracting color information from the luminance Y signal. Color difference signals form the basis for color information within component video signals. R-Y and B-Y (the basis for component video recording) or the related I (In phase) and Q (Quadrature) signals, the color difference signals used in NTSC.

Color Filter Array (CFA): A special multiple filter array that creates a linear or mosaic of color patterns over each pixel in a CCD that allows only one color to pass (red, green, or blue) through individual pixel elements. The CFA makes possible three-color imaging with only one imager.

Color Framing: A method of identifying correctness of color in a television system.

Color Under: The process of reducing the size of the signals color information to limit the bandwidth requirements. It offers cost-effective solutions suitable for analog, composite tape formats that do not require multiple generation capabilities. 3/4 inch U-matic¨, VHS, Beta, S-VHS, 8mm and Hi8ª are all color under formats.

Colorimetry: The measure of how well a camera reproduces the colors of the scene with respect to hue, saturation, and brightness.

Comb Filter: An electronic filter designed to separate chroma and luma information.

Communications Satellite: A satellite used to receive and re-transmit data, including video and audio signals and data. Communications satellites must be in geostationary, or geosynchronous, orbits.

Compander: Audio term: combination of compressor and expander. Another generic term for noise reduction unit.

Compile File: A list of ID's specifying the commercials to be recorded on a compiled tape. Durations specified in this file are checked against the LMSª database for accuracy, and any error is reported.

Compiling: The operation of recording replays prior to air time from the LMSª multi-cassette system's internal VTRs to an external VTR. Events to be recorded are specified in a compile file. Each compiled tape is identified by a ID encoded in a barcode label. Thus, tape is easily identified or for replay or in the event that revisions.

Component Video: A video signal that has not been encoded and retains the original color information as separate elements. Technically superior to encoded composite video. The transfer of the three-color video signals that describe a color image. The most common component systems are RGB and Y/R-Y/B-Y. Y stands for luminance or brightness, the sum of R, G, and B. By subtracting Y from (R-Y) and from Blue (B-Y), two color difference signals are produced which when transmitted with the Y signal can be used to recreate the original RGB color information.

Composite Sync: A signal containing all the timing pulses which are needed to lock the electron beam of the picture monitor in step, both horizontally and vertically, with the electron beam of the imaging device.

Composite Video: The part of a video process where the primary colors are combined or encoded into a composite signal. The most common type of video signal, in which the color (chrominance) and brightness (luminance) information is combined onto a single signal path. Composite signals are used in television broadcast and most video recording applications. Some image degradation results from combining the signals.

Compressed Time Div. Muxing.: Compressed Time Division Multiplexing. A process used in Betacam¨ recording. This effectively halves the size of the chroma signals so they can both be placed on the tape, adjacent to the un-compressed luma signal ensuring that the chroma signals coincide with the luma signals as they are read from the tape.

Compression: Reduction in the number of bits necessary to represent the information carried in the signal.

1. )Techniques used to reduce the size of digital signals so that they are easier to process, transmit, and store. Video and audio compression allows the conversion of analog signals to digital and reduces the number of bytes required to store those digital signals. Video, in particular, can be moved to and manipulated more efficiently when compression techniques are employed. There are several methods of compression for both audio and video available but no standard has been set as yet. For more information on both still image and motion image compression standards. (See JPEG and MPEG).

2.) The action taken by a video codec in reducing the data rate required for the transmission of television signals between sites.

Compression Ratio: In audio signal processing, the ratio of a compressor's input to output signal.

Compression Threshold: The level at which an audio compressor is activated.

Compressor (Audio): A device which reduces the dynamic range of a signal so that it can more easily be handled by an audio circuit or recording device.

Computer Conferencing: (1.) Interactive group communication in which a computer is used to receive, hold, and distribute messages between participants. Generally referred to as a store and forward medium; sometimes called interactive group electronic mail. (2.) Conferencing participants communicate using keyboards to transmit written messages to one another. Communication may be synchronous Ð interactive in real time. More commonly it is asynchronous: messages are stored in a central computer until retrieved by their intended recipients.

Condenser Microphone: A low-impedance type of microphone that operates on electrostatic principals. (See Electret Microphone).

Conditional Access: :A system which prevents unauthorized reception of signals by encrypting the signal and requiring specific centralized authorization of the subscriber's terminal to decode the signal.

Contention: :Multiple devices transmitting over the same media must contend for the right to transmit. Contention relies on statistical probability to manage resource sharing.

Continuous Presence: Used in videoconferencing applications. Most systems are equipped with cameras that can be panned, tilted, and zoomed in and out to capture meeting participants as the discussion moves around a conference room table; but sometimes an application calls for the ability to capture all participants all the time. The continuous presence option can be accomplished by taking the input from two cameras (usually with a fixed ÒcrossfireÓ view) and simultaneously displaying them on the monitors at the remote site by us in an image to the darkest possible area.

Control Track: A signal that is recorded onto videotape while video is recorded to make certain that the tape speed and head speeds are correctly synchronized with the original recording parameters. The lower portion along the length of a videotape on which sync control information is placed and used to control the recording or playing back of the video signal on a VTR.

Convergence: Proper alignment of the vertical and horizontal lines to ensure that red, blue, and green signals are correctly registered to produce a proper color image on video displays. Convergence circuits are found on color monitors and projectors.

Convergence Test Signal: Used to check and adjust the monitor or projector scanning linearity, aspect ratio, and geometric distortion. The signal is comprised of dots, vertical lines, horizontal lines, or any combination of the above.

CONUS:: Continental United States. Term is used to refer to the land area receiving radiated signals from a geostationary satellite.

Converter: :(1) The portion of the receiver which converts the incoming signal to the intermediate frequency. (2) In cable TV, an electronic device that will shift any television channel(s) from one to another channel within the UHF or VHF frequency spectrum.

Cosine Transform Coding: An algorithm or method used by some video codecs to compress digitized motion video images to very low data rates. Relies upon the mathematical transform referred to as the cosine transform. DCT (Discrete Cosine Transfer) is the method adapted for the world-wide H.261 standard for teleconferencing.

CPU: :Central Processing Unit.

CRC:: Cyclic redundancy code. Method of error checking.

Crossover Network: A device employed in audio monitors (speaker systems) that separates one range of frequencies from another. Two-way crossover networks would send lower frequency signals to the large speaker (woofer) while sending higher frequencies to the small speaker (tweeter).

Crosspoint: :The video switch which selects the source required on a particular switcher bus.

Crosstalk: Interference of one channel of electrical information with another adjacent channel. This could be from one stereo channel to another (e.g., left to right, right to left) or chroma and luma information in a video system.

CRT (Cathode Ray Tube): A vacuum tube that is the picture display device in television monitors. A CRT has a heater element (electron gun) at one end capable of producing a beam of electrons. The beam strikes the face of the tube which has been coated with special phosphors. When the beam strikes the phosphors, they glow in proportion to the signal strength striking them. By applying a scanning pattern (raster) to the beam, a television signal can be recreated as a picture on the tube surface.

Crystal Microphone: A high-impedance type of microphone found in inexpensive consumer electronic devices.

CSU (Channel Services Unit): A videoconferencing, telecommunications term: a CPE (Customer Premises Equipment {phone company term}) component which terminates a digital circuit such as a Tl line. The CSU performs line conditioning and interface functions and assures compliance to FCC regulations.

CTDM:: Compressed Time Division Multiplexed.

CTIA: :Cellular Telecommunications Industry Association.

Cue: To ready a source for playback. To locate the starting point.

Cue Out: A tone, pulse, or TTL type signal used as a communications trigger of events in editing. There are no standards for cue out, so it often requires a custom interface to make it compatible with other devices.

Cut: A visual technique where the picture changes instantaneously from one scene to an entirely different one.

CVD (Compact Videodisc):  Uses the 4.75-inch optical disc format to record analog video in the same format as larger CAV and CLV discs. It will support 20 minutes of video on a CLV disc (no still frames or random access) and 10-12 minutes on a CAV disc (random access and special features). There are a limited number of titles available today- primarily music videos.

Cycle Time: LMSª system term, the shortest duration possible between accessing individual segments in a play list.

Cycles Per Second: See Hertz.