18WuD2x

cutoff frequency • cyclic variations 161
of a transistor drops to 70.7% of its 1-kHz value.
2. In a filter, amplifier, or transmission line, the
frequency point(s) at which transmission loss or
filter rejection begins. It is generally specified as
the half-power point(s), or the point(s) at which
the attenuation is three decibels, relative to
the lowest attenuation. Examples: the highfrequency
cutoff of an amplifier and the upper
and lower cutoff points of a bandpass filter.
cutoff limiting Output-peak clipping that results
from overdrive in an amplifying device. Compare
SATURATION LIMITING.
cutoff potential See CUTOFF BIAS.
cutoff voltage See CUTOFF BIAS.
cutoff wavelength 1. The wavelength corresponding
to cutoff frequency. 2. For a waveguide, the
ratio of the velocity of electromagnetic waves in
free space (3 × 10 8 meters per second) to the cutoff
frequency of the waveguide in Hz. The result is
thus expressed in meters.
cutout
1. A device, such as a circuit breaker, that
automatically disconnects a circuit, usually to
prevent overload, but occasionally to prevent underload.
2. Emergency switch. 3. Fuse.
cut-out angle In a semiconductor rectifier circuit,
a phase angle slightly less than 180 degrees at
which current conduction ceases. Compare CUT-
IN ANGLE.
cutout base A fuse block.
cut rate 1. The speed at which a cutter moves
across the surface of a blank vinyl disk during the
recording process. 2. The number of cut lines per
inch in a vinyl disk recording.
CW 1. Abbreviation of CONTINUOUS WAVE. 2. Abbreviation
of CLOCKWISE.
CW filter In a communications receiver, a highly
selective filter in the intermediate-frequency (IF)
or audio-frequency (AF) stage. The bandwidth is
typically 200 Hz to 500 Hz; some audio filters
can be set for bandwidths as low as about 50
Hz.
CW laser A laser that emits energy in an uninterrupted
stream, rather than in pulses.
CW monitor See KEYING MONITOR.
CW oscillator 1. In a radio receiver, a variablefrequency
oscillator that heterodynes a radiotelegraph
signal in the intermediate-frequency (IF)
amplifier chain, to make audible the continuouswave
dits and dahs. 2. Sometimes, an external
variable-frequency radio-frequency (RF) oscillator,
whose output beats against the actual carrier
of a continuous-wave radiotelegraph signal, making
it audible as dits and dahs. 3. An unmodulated,
unkeyed oscillator.
CW radar A radar system in which radio-frequency
(RF) energy is transmitted continuously.
CW reference signal A sinusoidal radiofrequency
(RF) signal, used to control the conduction
time of a synchronous demodulator in
color television.
C x
Symbol for UNKNOWN CAPACITANCE.
cyan Blue-green, one of the three primary pigments.
cyber- A prefix that indicates relevance to, or involvement
with, computers, computer systems,
and electronic control systems.
cybernetics The study of control system theory in
terms of the relationship between animal and
machine behavior.
Cyber Sapiens An expression for a computer or
robot with artificial intelligence (AI) on the forefront
of current technology.
cyberspace 1. Alternative expression for INFOR-
MATION SUPERHIGHWAY. 2. Alternative expression
for VIRTUAL REALITY.
cyborg Acronym of the words cybernetic and organism.
1. A human being with at least one artificial
body part, such as a prosthesis (artificial
limb). 2. A human being who is largely composed
of robotic body parts.
cycle 1. Abbreviation, c. One complete, 360-degree
revolution of the current or voltage vector in an
alternating-current (ac) wave. An ac frequency of
1 cycle per second is 1 Hz (see HERTZ). 2. A complete
sequence of operations.
cycle counter A device that totals the number of
cycles of a phenomenon repeated during a given
period.
cycle index The number of times that a particular
cycle has been, or must be, iterated in a computer
program.
cycle index counter A variable that indicates how
often a cycle of computer program instructions
has been executed. In a program, for example,
this can be accomplished by increasing, through
instruction, the value of a location’s content every
time a loop operation is performed.
cycle life The total number of charge-discharge cycles
a rechargeable cell or battery can tolerate before
becoming useless.
cycle reset To change the value of a cycle count
(making it zero or some other value).
cycle shift See CYCLIC SHIFT.
cycles per second Abbreviation, cps. Archaic term
for HERTZ.
cycle time Pertaining to an operation, the duration
of a complete cycle.
cycle timer A timer that switches a circuit or device
on and off, according to a predetermined cycle.
Also called programmed timer.
cyclic code See GRAY CODE.
cyclic memory In computer operations, a memory
whose locations can only be accessed points in a
cycle, as of a magnetic diskette.
cyclic shift The moving of data out of one end of a
storage register and reentering it character-bycharacter
or bit-by-bit at the other end in a closed
loop (e.g., 87654 cyclically shifted one place to
the right becomes 48765).
cyclic variations Periodic changes in the features
of the ionosphere, occurring on a daily, seasonal,
or sunspot-related basis. These changes are fairly
predictable.