Please select a letter for terms starting with that letter:

- B -

Brightness
The thing that makes darkness go away, measured in lumens on a projector.

Bulb
A light source commonly mistaken for the lamp module in a projector. Bulbs provide incandescent room lighting. Lamp modules provide light for projected images.

B Channel
The ISDN circuit-switched bearer channels, capable of transmitting 64 Kbps of digitized information.

B-Router
Concatenation of "bridge" and "router". Used to refer to devices which perform both bridging and routing functions.

Back porch
The time in a composite video signal that lies between the trailing edge of the horizontal-sync pulse and the trailing edge of the corresponding blanking pulse. The back porch precedes video information.

Balanced Audio
A method that uses three conductors for one audio signal. They are plus (+), minus (-) and ground. The ground conductor is strictly for shielding and carries no signal. Also Differential Audio.

Bandwidth
A frequency range, or "band" of frequencies, within which a device operates. The capacity of any single channel of the system to transmit data. In audio and video, it is the band of frequencies that can pass through a device without significant loss or distortion. The higher the bandwidth, the sharper the picture; low bandwidth can cause a "fuzzy" picture.

Barrel
An visual effect when a displayed image curves outward at the middle of each edge curve outward. Also see Pin Cushion. CRT devices often have a pin cushion adjustment to counter this effect.

Baseband
The basic direct output signal in an intermediate frequency based obtained directly from a television camera, videoconference television receiver, or video tape recorder. Baseband signals can be viewed only on studio monitors. To display the baseband signal on a conventional television set a modulator is required to convert the baseband signal to one of the VHF or UHF television channels which the television set can be tuned to receive.

BASIC
An acronym for Beginner's All-purpose Symbolic Instruction Code. A computer programming language.

Baud
The commonly used unit of speed that describes the rate at which binary data is transmitted. One baud is approximately equal to one bit per second. Common baud rates are 300, 1200, 2400, and 9600 bps (bits per second).

Baud Rate
Term used to measure data transfer rate. Baud rate is equivalent to bits per second at low speeds, e.g., 300 baud is the same as 300 bps. At higher speeds the bits per second is greater than the baud rate, since one baud can be made to represent more than one bit.

Binary Code
A coding system in which each element has one of only two possible values, one or zero.

Bit
Contraction of "binary digit," The smallest unit in computer data handling (either a zero or a one) equal to one binary decision. A computer's processing capability is usually measured by the number of bits that can be handled at one time.

Bit Error Rate
The fraction of a sequence of message bits that are in error causing possible break-up of transmission of data, voice or video. A bit error rate of 10-6 means that there is an average of one error per million bits.

Bit Map
The total of all bit planes used to represent a graphic. Its size is measured in horizontal, vertical and depth of bits. In a one-bit (monochrome) system there is only one bit plane. As additional planes are added color can be described. Two bit planes yield four possible values per imagesel; eight yield 256, and so on.

Bit-Mapped Graphics
A form of graphics that are defined and addressed on a bit-by-bit basis, thereby making all points on the screen display directly accessible.

Bit Rate
The number of binary bits transmitted per time unit. Speed of a digital transmission, measured in bits per second.

Bits Per Second (BPS or b/s)
A unit of measurement of the speed of data transmission and thus of bandwidth.

Black & White
Monochrome or luminance information. Monochrome means one color. In the color television system the black and white portion of the picture has to be one "color"; gray, D6500, at a color temperature of 6500K as defined by x and y values in the 1939 CIE color coordinate system.

Blanking
The turning off of the electron beam that scans the image onto the screen. When the beam completes a scan line it must return (retrace) back to the left. During this time, the beam must be turned off (horizontal blanking). Similarly, when the last line has been scanned at the bottom of the screen, the beam must return to the upper left. This requires vertical blanking. An typical television signal consists of 30 separate still pictures or frames sent every second. They occur so rapidly, the human eye blurs them together to form an illusion of moving pictures. This is the basis for television and motion picture systems. The blanking interval is that portion of the television signal which occurs after one picture frame is sent and before the next one is transmitted. During this period of time special data signals can be sent which will not be picked up on an ordinary television receiver.

Blanking Level
It is the level of a video signal which separates the range that contains the picture information from the range that contains the sync information. The level of the front and back porches or zero IEEE units.

Bleed
An effect that appears in a passive-matrix panel where a faint "ghost" of an object is seen beyond the object's boundaries.

Blooming
Most noticeable at the edges of images on a CRT, "blooming" is when the light (color) is so intense that it seems to exceed the boundary of the object. Thin lines and sharp edges can look thick and fuzzy. This may be caused by the brightness being set too high or by a high voltage problem.

Blue Enhancement
Mixes the right amount of blue information with the green signal for displaying text in a more readable "aqua" color. This color mixing affects all blue colors on the display screen (only used for TTL signals).

BNC
A electrical signal connector having a cylindrical bayonet termination point. BNC connectors operate with a twist-locking motion. Two curved grooves in the collar of the male connector are aligned with two projections on the outside of the female collar. This allows the connector to be locked in place without the need for tools.

Bookmark
A marker left in a multimedia or CBT program that allows the user to return to a particular event at a later time.

Boost Control
Extron's boost control can compensate for losses of signal level or picture contrast due to an increase in resistance as cable length increases. Depending on cable specifications, a 50% boost may improve picture quality for lengths of 125-500 feet. Note: The boost control can variably adjust the output level. For example, a 50% boost equals 1.25 volts peak to peak. A 100% boost equals 1.45 volts peak to peak.

Boot/Boot-Up/Bootstrap
The initialization process a computer undertakes immediately after power up. Evolved from the phrase "to begin again" or to "pull yourself up by your bootstraps". Also occurs with a computer "reset."

Bow
The curving of scan lines in the center of the image.

BPS
Acronym for bits per second.

Branch
A segment selected from the response of the user or viewer. To jump from one location to another in a multimedia program.

Breakaway
The ability to separate signals for the purpose of switching them independently. For example: an audio and video signal from the same source may be "broken away" and switched to different destinations. This is the opposite of the term "follow".

Breezeway
The early part of the Back Porch portion of the video signal. The area between the signal's horizontal sync pulse and the color bust.

Brightness Ratio
The difference between the brightest and darkest object in a picture. Too much of a difference can cause unacceptable contrast.

Bridge
In videoconferencing vernacular, a bridge connects three or more conference sites so that they can simultaneously communicate. Bridges are often called MCUs (Multipoint Conferencing Units). In IEEE 802 parlance, a bridge is a device that interconnects LANs or LAN segments at the data-link layer of the OSI model to extend the LAN environment physically. They work with frames (as opposed to packets) of data, forwarding them between networks. A bridge learns station addresses and resolves problems with loops in the topology by participating in the spanning tree algorithm. Finally, the term bridge can be used in audio conferencing to refer to a device that connects multiple (more than two) voice calls so that all participants can hear and be heard.

Broadband
The term applied to networks having bandwidths significantly greater than that found in telephony networks. Broadband systems are capable of carrying a large number of moving images or a vast quantity of data simultaneously. Broadband techniques usually depend on coaxial or optical cable for transmissions. They utilize multiplexing to permit the simultaneous operation of multiple channels or services on a single cable. Frequency division multiplexing or cell relay techniques can both be used in broadband transmission.

Broadcast
A packet delivery system where a copy of given packet is given to all hosts attached to the network. Example: Ethernet.

Brightness Signal
Same as the luminance (Y). A signal which carries information about the amount of light at each point in the image.

Buffer
A storage device or circuit that temporarily retains and then transmits information to or from the host computer or peripheral device. Generally referred to as a unity gain (gain of 1) amplifier used to isolate the signal source from the load. Buffers can be used for both digital and analog signals.

Bug
A flaw or error in a computer program.

Build Slide
A "build slide" shows an audience a presenter's topic one line at a time. Each new line appears in a bright color while the previous line "drops back" to a darker color.

Burn-In
In video display, a term to describe when an image has been displayed  too long on a device, resulting in a permanent image being "burned in" to the device's display. Burn in can occur on CRT, plasma, and some other video display devices.

Bus
A circuit or group of circuits that provide(s) an electronic path between the central processing unit (CPU) or input/output devices.

Button
A graphic element within an interface that represents an embedded action or function.

Byte
A unit of computer memory (developed by IBM) used to store numeric or character information. Bytes of eight bits normally reflect either one character or two numerals.

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