Backup: A system, device, file or facility that can be used as an alternative in case of a malfunction or loss of data.

Bandwidth: A symmetrical region around the set point in which proportional control occurs. In analog signals, the difference between a signal's lowest frequency component and its highest component as measured in Hz. The speed of a digital communications circuit in bits per second.

Base Station: The central transmitter in a communications system that acts as the cell hub for communicating with handsets and/or mobile units.

Baseband Signal The frequency bandwidth of the fundamental signal of interest.

Basic Transportation Reference: The basic transportation section of the U.S. Government Test Specification MIL-STD-810D, Method 514.3, Paragraph I-3.2.1, Page 514.3-5. Basic transportation defines the test profiles that have been defined for equipment that is shipped as secured cargo; by land, by sea or by air. The test levels are based upon land transport stress levels because these are higher than stresses imposed by air or sea transportation environments.

Basic: A high-level programming language designed at Dartmouth College as a learning tool. Acronym for Beginner's All-purpose Symbolic Instruction Code.

Baud: A unit of data transmission speed equal to the number of bits (or signal events) per second; 300 baud = 300 bits per second.

Baud Rate: The speed at which data is transmitted. Measured in symbols per second. This is not the same as bits-per-second since each symbol can carry several bits of information.

BCD, Buffered: Binary-coded decimal output with output drivers, to increase line-drive capability.

BCD, Parallel: A digital data output format where every decimal digit is represented by binary signals on four lines and all digits are presented in parallel. The total number of lines is 4 times the number of decimal digits.

BCD, Serial: A digital data output format where every decimal digit is represented by binary signals on four lines and up to five decimal digits are presented sequentially. The total number of lines is four data lines plus one strobe line per digit.

BCD, Three-State: An implementation of parallel BCD, which has 0, 1 and high-impedance output states. The high-impedance state is used when the BCD output is not addressed in parallel connect applications.

Best Fit Straight Line (BFSL): A line midway between two parallel straight lines enclosing all output vs. pressure values.

Beta Ratio: The ratio of the diameter of a pipeline constriction to the unobstructed pipe diameter.

BIAS Current: A very low-level DC current generated by the panel meter and superimposed on the signal. This current may introduce a measurable offset across a very high source impedance.

Binary Coded Decimal (BCD): The representation of a decimal number (base 10, 0 through 9) by means of a 4 bit binary nibble.

Binary: Refers to base 2 numbering system, in which the only allowable digits are 0 and 1. Pertaining to a condition that has only two possible values or states.

BIOS: Acronym for basic input/output system. The commands used to tell a CPU how it will communicate with the rest of the computer.

Bipolar: The ability of a panel meter to display both positive and negative readings.

Bit: Acronym for binary digit. The smallest unit of computer information, it is either a binary 0 or 1.

Bit Rate: The rate of transfer of information necessary to ensure satisfactory reproduction of the information at the receiver.

Blackbody: A theoretical object that radiates the maximum amount of energy at a given temperature, and absorbs all the energy incident upon it. A blackbody is not necessarily black. (The name blackbody was chosen because the color black is defined as the total absorption of light energy.)

BNC: A quick disconnect electrical connector used to inter-connect and/or terminate coaxial cables.

Boiling Point: The temperature at which a substance in the liquid phase transforms to the gaseous phase; commonly refers to the boiling point of water which is 100°C (212°F) at sea level.

BPS: Bits per second.

Breakdown Voltage Rating: The dc or ac voltage which can be applied across insulation portions of a transducer without arcing or conduction above a specific current value.

Bridge: A Wheatstone bridge configuration utilizing four active strain gages.

Bridge Resistance: The nominal value of the individual legs that make up a complete Wheatstone bridge.

Broadcast: The process of sending a message from one station to all other stations on the network.

Brouter: A device that performs the functions of both a bridge and a router.

BTU: British thermal units. The quantity of thermal energy required to raise one pound of water at its maximum density, 1 degree F. One BTU is equivalent to .293 watt hours, or 252 calories. One kilowatt hour is equivalent to 3412 BTU.

Buffer Amplifier: A unity gain amplifier used to isolate the loading effect of one circuit from another. Buffer amplifiers are almost always used between the signal source and the input of a high-speed A/D convertor.

Buffer Capacity (B): A measure of the ability of the solution to resist pH change when a strong acid or base is added.

Buffer: 1. A storage area for data that is used to compensate for a speed difference, when transferring data from one device to another. Usually refers to an area reserved for I/O operations, into which data is read, or from which data is written.2. Any substance or combination of substances which, when dissolved in water, produces a solution which resists a change in its hydrogen ion concentration on the addition of an acid or alkali.

Burn-In: A long term screening test (either vibration, temperature or combined test) that is effective in weeding out infant mortalities because it simulates actual or worst case operation of the device, accelerated through a time, power, and temperature relationship.

Burst Pressure: The maximum pressure applied to a transducer sensing element or case without causing leakage.

Burst Proportioning: A fast-cycling output form on a time proportioning controller (typically adjustable from 2 to 4 seconds) used in conjunction with a solid state relay to prolong the life of heaters by minimizing thermal stress.

Bus Network: A network topology that uses a single communications link to connect three or more terminals. Also called a Multi-Drop Network.

Byte: The representation of a character in binary. Eight bits in length.