Page 106 - Electrical Engineering Dictionary

broadcast picture quality the accept- brownout an intentional lowering of util-
able picture performance for NTSC terres- ity voltage to reduce loading on the system.
trial telecast signals. A panel of untrained
observers subjectively evaluates the NTSC brush a conductor, usually carbon or a
received picture and sound quality as signal carbon–copper mixture, that makes sliding
impairments are inserted into the broadcast electrical contact to the rotor of an electri-
signal. The evaluation scores are used to cal machine. Brushes are used with sliprings
determine the values for objectionable sig- on a synchronous machine to supply the DC
nal impairment levels. The signal impair- field and are used with a commutator on a DC
ments tested are the video and audio signal- machine.
to-noise ratios, the interference due to adja-
cent channel signals, the interference due to brush rigging the components used to
co-channel signals, and the echoes (ghosts) hold the brushes of a rotating machine in
caused by multipath signals effects. place, and to insure proper brush tension is
applied.
broadcasting sending a message to mul-
tiple receivers.
brush tension the force required on the
brushesofarotatingmachinetoinsureproper
broadside when the pattern factor is
contact between the brush and the commuta-
maximum in the H plane (for a dipole an-
tor or slipring. Proper brush tension is usu-
tenna along the z axis this is the plane where
ally provided by springs, and is specified in
theta=90 degrees).
the manufacturer’s technical manual of the
machine.
broadside array an array where the main
beam of the array is directed perpendicular
brushless DC motor See electronically
to the array axis. In many applications it is
commutated machine.
desirable to have the maximum radiation of
an array directed normal to the axis of the
array. brushless exciter See rotating-rectifier
exciter.
broadside coupled microstrip lines mi-
crostrip lines that share the same ground brushless rotary flux compressor a ro-
plane but separated from each other in normal tating machine designed to deliver pulsed
direction to the ground plane. Both the mi- output (1 MJ in 100 µs). The stator coils are
crostriplinesarealignedattheircentersalong excited by an external capacitor bank. The
the normal direction to the ground plane. rotor is a salient structure that compresses
the flux resulting in amplification of the elec-
Brown book See IEEE Color Books. tric pulse, by converting the rotating kinetic
energy of the rotor to electrical energy.
Brownian motion a stochastic process
with independent and stationary increments. BSO abbreviation for bismuth silicon ox-
The derivative of such a process is a white ide, Bi 4 SiO 20 . A photoconductive insulat-
noise process. A Brownian motion process ing crystal that exhibits photorefractive ef-
X t is the solution to a stochastic differential fects. Useful in applications such as multi-
equation of the form beam coupling and phase conjugation.

dX
= b(t, X t ) + σ(t, X t ) · W t , BTB See branch target buffer.
dt
where W t is a white noise process. BTC See block truncation coding.

c
2000 by CRC Press LLC