Page 17 - The Illustrated Dictionary of Electronics

5059F-pA_1-55 4/9/01 4:41 PM Page 2

2 abhenry • absolute error

and is the inductance across which a current
that changes at the rate of 1 abampere per sec-
ond induces a potential of 1 abvolt.
ABL Abbreviation of Automated Biology Laboratory
(NASA).
abmho The obsolete unit of conductance and of
conductivity in the cgs electromagnetic system.
Replaced with ABSIEMENS.
abnormal dissipation Power dissipation higher or
lower than the customary level, usually an over-
load.
abnormal oscillation 1. Oscillation where none is
desired or expected, as in an amplifier. 2. Oscilla-
tion at two or more frequencies simultaneously
when single-frequency operation is expected.
3. Oscillation at an incorrect frequency. 4. Parasitic
oscillation.
abnormal propagation 1. The chance shifting of absence-of-ground searching selector A rotary
the normal path of a radio wave, as by displace- switch that searches for an ungrounded contact
ments in the ionosphere, so that reception is de- in a dial telephone system.
graded. 2. Unintentional radiation of energy from absiemens The unit of conductance or conductiv-
some point other than the transmitting antenna. ity in the cgs electromagnetic system. One
3. Propagation over a path or in a direction not absiemens equals 10 9 siemens and is the
expected. conductance through which a potential of 1 ab-
abnormal reflections Sharp, intense reflections at volt forces a current of 1 abampere.
frequencies higher than the critical frequency of absolute 1. A temperature scale in which zero repre-
the ionosphere’s ionized layer. sents the complete absence of heat. Units of mea-
abnormal termination The shutdown of a running sure are same as units on Celsius and Fahrenheit
computer program or other process. Caused by scales. See ABSOLUTE SCALE. 2. Independent of
the detection of an error by the associated hard- any arbitrarily assigned units of measure or value.
ware that indicates that some ongoing series of absolute accuracy The full-scale accuracy of a me-
actions cannot be executed correctly. ter with respect to a primary (absolute) standard.
abnormal triggering The false triggering or switch- absolute address In a digital computer program,
ing of a circuit or device, such as a flip-flop, by the location of a word in memory, as opposed to
some undesirable source instead of the true trigger location of the word in the program.
signal. Electrical noise pulses often cause abnor- absolute code A computer code in which the exact
mal triggering. address is given for storing or locating the refer-
abohm The unit of resistance and of resistivity in ence operand.
the cgs electromagnetic system. One abohm absolute coding In computer practice, coding that
equals 10 –9 ohms and is the resistance across uses absolute addresses.
which a steady current of 1 abampere produces a absolute constant A mathematical constant that
potential difference of 1 abvolt. has the same value wherever it is used.
abort To deliberately terminate an operation, ex- absolute delay The time elapsing between the
periment, process, or project before it has run its transmission of two synchronized signals from
normal course. the same station or from different stations, as in
AB power pack 1. A portable dry-cell or wet-cell radio, radar, or loran. By extension, the time in-
array containing both A and B batteries in one terval between two such signals from any source,
package. 2. An ac-operated unit in one package as from a generator.
for supplying A and B voltages to equipment nor- absolute digital position transducer A digital po-
mally operated from batteries. sition transducer whose output signal indicates
abrasion machine An instrument for determining absolute position. (See ENCODER.)
the abrasive resistance of a wire or cable. absolute efficiency The ratio X x/X s, where X x is
abrasion resistance A measure of the ability of a the output of a given device, and X s is the output
wire or wire covering to resist mechanical dam- of an ideal device of the same kind under the
age. same operating conditions.
ABS A basic programming abbreviation for the ab- absolute encoder system A system that permits
solute value (of a number, variable, or expres- the encoding of any function (linear, nonlinear,
sion). continuous, step, and so on) and supplies a non-
abscissa 1. The independent variable in a function. ambiguous output.
2. The axis (usually horizontal) on the graph of a absolute error The difference indicated by the ap-
function that indicates the independent variable. proximate value of a quantity minus the actual