**Glossary B**

**Background Noise:** The total noise floor from all sources of interference in a measurement system, independent of the presence of a data signal.

**Back Electromotive Force:** (back emf) The emf that opposes the normal flow of current in a circuit.

**Bandwidth:** 1) A symmetrical region around the set point in which proportional control occurs. 2) A frequency range.

**Base:** One terminal of a transistor. Generally the input lead. It separates the collector and emitter regions.

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

**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.

**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 Numbers:** 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.

**Bipolar Transistor:** The most common form of transistor.

**Bistable:** Circuit that has two stable states.

**Bit:** Binary Digit - the smallest unit of binary data. See also byte.

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

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

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

**Bottoming:** A transistor in the fully conducting state.

**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:** generally a short-circuit on a PC board caused by solder joining two adjacent tracks.

**Bridge rectifier:** a full-wave rectifier in which there are four arms - each containing a diode.

**Bus:** Parallel lines used to transfer signals between devices or components. Computers are often described by their bus structure (i.e., S-100, IBM PC).

**By-pass capacitor:** A capacitor that provides a path of low impedance - low resistance to AC signals.

**Byte:** A group of binary digits that combine to make a word. Generally 8 bits. Half byte is called a nibble. Large computers use 16 bits and 32 bits.