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television • temperature derating 677
television 1. Abbreviation, TV. The transmission
and/or reception, via electromagnetic fields, wire
cable, and/or fiberoptic cable, of images, usually
with sound. 2. A system for receiving signals, as
defined in 1. 3. Video programs or data, with or
without sound, transmitted via electromagnetic
fields, wire cable, and/or fiberoptic cable.
television band See UHF TELEVISION CHANNELS
and VHF TELEVISION CHANNELS.
television camera The pickup device that scans a
scene and delivers a series of electrical signals
that can be used to reconstruct the image on the
screen of a picture tube.
television-camera tube See CAMERA TUBE,
ICONOSCOPE, and ORTHICON.
television channel A radio-frequency band allocated
exclusively for the transmission of a television
signal. In conventional broadcasting, this
band is usually 6 MHz wide. See, specifically,
UHF TELEVISION CHANNELS and VHF TELEVI-
SION CHANNELS.
television engineer A trained professional skilled
in video electronics engineering, as well as in basic
engineering and associated subjects.
television engineering The branch of electronics
engineering devoted to the theory and application
of television.
television interference Abbreviation, TVI. Interference
to the reception of television signals, usually
occasioned by signals from radio services or
computers, or by electrical noise.
televisor 1. A television transmitter or receiver.
2. A person or entity responsible for the broadcast
of television programs or signals.
televoltmeter A TELEMETER for measuring voltage
generated at a remote point.
telewriter See TELAUTOGRAPH.
Telex 1. A teleprinter system that operates via the
telephone lines, and was once commonly used by
businesses for sending and receiving short messages.
It has largely been supplanted by computerized
data communications systems. 2. A hard-copy
message sent or received by such a system.
telluric currents Also called terrestrial currents.
A flow of electrical charge carriers, primarily electrons,
in the earth.
tellurium Symbol, Te. A rare, metalloidal element
related to selenium. Atomic number, 52. Atomic
weight, 127.60.
TE mode See TRANSVERSE ELECTRIC MODE.
temp 1. Abbreviation of temperature. (Also, T.)
2. Abbreviation of temporary. 3. Abbreviation of
TEMPLATE.
temperament The tuning of a keyboard-type musical
instrument to produce a nearly perfect diatonic
scale.
temperature Symbol, T. A quantitative measure of
the heat exhibited by an object or phenomenon.
Also see THERMOMETER SCALE.
temperature coefficient A figure that states the
extent to which a quantity drifts or varies under
the influence of changing temperature. It is generally
expressed in percent per degree (%/°C) or
in parts per million per degree (ppm/°C).
temperature-compensated crystal oscillation
Oscillation in a crystal oscillator, in which the
crystal and/or circuit is automatically compensated
against frequency drift caused by temperature
change.
temperature-compensating component A circuit
component, such as a capacitor or resistor, whose
temperature coefficient is equal in magnitude and
opposite in sign to that of a conventional component
to which it is connected to cancel temperature-induced
variation in the latter’s value.
Tank capacitor
Tuning
control
Temperaturecompensating
capacitor
temperature-compensating component
temperature compensation The use of a device,
such as a temperature-compensating component,
to correct a temperature-induced deviation
in the value of a conventional component.
temperature control 1. The adjustment of temperature.
2. The automatic maintenance of temperature
at a desired level, as in a
temperature-controlled oven. 3. A device for controlling
temperature, as defined in 1 or 2.
temperature-controlled crystal oscillator Abbreviation,
TCCO. A high-precision crystal oscillator
in which the crystal plate (and sometimes the circuitry,
as well) is held at constant temperature.
temperature degree See DEGREE, 2 and THER-
MOMETER SCALE.
temperature derating Deliberate reduction of operating
current and/or voltage of a device to a
specific temperature to ensure proper operation.
Also see DERATING, DERATING CURVE, and
DERATING FACTOR.