Page 84 - The Illustrated Dictionary of Electronics

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beat note • Be0 69

beat note The sum or difference frequency that re- a hollow metal sphere at the upper end, where
sults from the heterodyning of two signals or, un- they are removed and spread to the surface of the
der some conditions, of more than two signals. sphere, which they raise to a potential up to sev-
beat-note reception 1. Reception in which a ra- eral million volts.
dio-frequency carrier is made audible by hetero- benchmark A test standard to measure product
dyning it with a beat-frequency oscillator (BFO) to performance.
produce an audible beat note. 2. Superhetero- benchmark routine A routine designed to evaluate
dyne reception (see SUPERHETERODYNE CIR- computer software and/or hardware, producing a
CUIT). good indication of how well the software or hard-
beat tone A beat note in which the frequency is ware will perform in real-life situations. In par-
within the range of hearing. ticular, tests instructions per second and
beaver tail A flat or elongated radar beam, wide in throughput, thereby producing an indication of
the azimuth plane. Primarily used to determine the overall computer power in applications, such
the altitude of a target. The beam is moved up as word processing, database, spreadsheet,
and down to find the target elevation. graphics, animation, and mathematical calcula-
Becquerel effect A phenomenon in which a volt- tions.
age is produced when radiant energy, such as in- bench test An extensive checkout of a piece of
frared, visible light, ultraviolet, or X-rays, falls on equipment in the test laboratory—either to find
one electrode in an electrolytic cell. an intermittent problem, or to check for reliabil-
bedspring A directional antenna consisting of a ity.
broadside array with a flat reflector and one or bend An angular shift in the lengthwise direction of
more helical driven elements. a waveguide.
beep A test or control signal, usually of single tone bending effect 1. The downward refraction of a
and short duration. radio wave by the ionosphere. 2. The low-
beeper 1. A pocket- or hand-carried transceiver— atmosphere turning of a radio wave downward by
especially one for maintaining two-way contact temperature discontinuity and atmospheric in-
with personnel who are away from their base. 2. versions.
An acoustic transducer that produces a beep in Benito A continuous-wave method of measuring
response to an input signal. the distance of an aircraft from the ground, in-
beetle A urea formaldehyde plastic used as a di- volving the transmission of an audio-modulated
electric material and as a container material. signal from ground and the retransmission back
bel Abbreviation, B. The basic logarithmic unit to ground by the aircraft. The phase shift between
(named for Alexander Graham Bell) for express- the two signals is proportional to the distance to
ing gain or loss ratios. One bel is equivalent to a the aircraft.
power gain of 10. Also see DECIBEL. bent antenna An antenna that has its driven ele-
bell An electric alarm device consisting of a metal- ment bent, usually near the ends and at right an-
lic gong that emits a ringing sound when it is gles, to conserve space.
struck by an electrically vibrated clapper. bent gun A television picture tube neck arrange-
Bellini-Tosi direction finder A direction finder in ment having an electron gun that is slanted to di-
which the sensing element consists of two trian- rect the undesired ion beam toward a positive
gular vertical antennas crossed at right angles, electrode, but which allows the electron beam to
the antennas being open at the top and accord- pass to the screen. This prevents the ion beam
ingly not acting as conventional coil antennas. from “burning” a permanent spot on the phoso-
bell-shaped curve A statistical curve (so called por of the screen.
from its characteristic shape) that exhibits a nor- Be0 Formula for beryllium oxide. Also see BERYL-
mal distribution of data. Typically, the curve de- LIA.
scribes the distribution of errors of measurement
around the real value.
bell transformer A (usually inexpensive) stepdown Ion trap
transformer that operates an electric bell or simi- Cathode magnet
lar alarm or signaling device from the ac power First anode
line. Second anode
bell wire Insulated 18-gauge (AWG) solid copper
wire, so called because of its principal early use
in the wiring of electric-bell circuits. Electron
belt generator Also known as a Van de Graaff gen- beam
erator. A very-high-voltage electrostatic genera-
tor, a principal part of which is a fast-traveling Control
endless belt of dielectric material. At the lower grid
end, charges of one sign are sprayed on the belt
at 10 to 100 kV dc and are carried to the inside of bent gun