B Channel (Bearer
channel) |
A 64-kbps ISDN user channel that carries digital data or a PCM-encoded digital voice. BIOS (Basic Input/Output System) The part of a computer’s operating system that handles the flow of data between software and hardware. For example, a program’s request to save a file to disk goes through the BIOS. |
B.L.C. (Back Light
Compensation) |
A feature of modern CCD cameras which electronically compensates for high background lighting to give detail which would normally be silhouetted. |
| Back Focus |
The mechanical aligning of the imaging device with the focal point of the lens. Most important on zoom lenses to ensure the image stays in focus throughout the zoom range. |
| Balanced Signal |
Method of transmitting video, usually over twisted pair cable, that consists of two equal but opposite signals being sent down two conductors. |
Balun (Balanced
Unbalanced) |
A device that connects a balanced line, such as twisted pair, to an unbalanced line, such as coax cable. |
| Band Width |
The frequency range that an electronic circuit can accept. |
| Bandwidth |
The range of frequencies available for signalling the difference between the highest and lowest frequencies of a band, measured in Hertz. |
| Base-Band Video |
Unmodulated video signal suitable for display on a monitor but not a domestic TV. |
| Baseband |
A full-channel bandwidth transmission where digital signals are placed onto a transmission line with no change in their modulation. |
| Baud |
Unit of signalling speed. The speed in baud is the number of line changes (in frequency, amplitude, etc.) or events per second. At low speeds, each event represents only one bit condition, and baud rate equals bps. As speed increases, each event represents more than one bit and baud rate does not truly equal bps. |
| Baud rate |
Data transmission speed. |
| Bit (Binary Digit) |
The smallest unit of information in a binary system; a one or zero condition. |
| Black Level |
The level on a video signal, just above the sync pulses, where black portions of the picture are represented. |
Blanking (Field and
line flyback
blanking) |
The operation of turning off the monitor display, or pick-up device, during sync pulses to avoid thin white lines appearing on the picture. |
| BNC |
Video connector, the most commonly used in CCTV. |
BRI (Basic Rate
Interface) |
An ISDN service referred to as 2B+D, BRI provides two 64-kbps bearer digital channels plus a 16-kbps delta channel. ISDN terminal adaptors replace moderns as the customer-premise connection to this service for direct connections of data and voice transmissions. |
| Bridge |
A device that connects two LAN segments together, which may be of similar or dissimilar types, such as Ethernet and Token Ring. |
| Byte |
A unit of information, usually shorter than a computer "word." Eight-bit bytes are most common. Also called a "character." Category 1 through 5 cables (CAT 1-5) The following categories are based on their transmission capacity. Categories 1 through 5e are based on the TIA/EIA-568 standard.
CABLE TYPE APPLICATION
1 UTP Analogue Voice
2 UTP Digital Voice, 1-Mbps Data
3 UTP, STP 16-Mbps Data
4 UTP, STP 20-Mbps Data
5 5e UTP STP 100-Mbps Data |
