18WuD2x

692 transit angle • transverse
transit angle For an electron, the angular frequency
multiplied by the time required to travel
from one point to another.
transit time The time taken by an electron to
travel from one electrode to another—especially
from the cathode to the plate in a vacuum tube.
transistor element A metallic element whose
atoms have valence electrons in two shells. Examples:
chromium, iron, and nickel.
transition factor See MISMATCH FACTOR.
transition region See BARRIER, 1.
translation loss See PLAYBACK LOSS.
translator 1. See COMPILER. 2. See ASSEMBLER.
transliteration 1. To change the characters in one
alphabet or code system to the characters in a
different system. 2. The function that maps the
characters in one alphabet or code system to
those in another.
translucence 1. The transmission of radiation, especially
visible light, through a material. 2. The
extent to which a substance can transmit radiation—especially
visible light. 3. Pertaining to a
material that partially or totally transmits radiation—especially
visible light.
transmission gain Current amplification, power
amplification, or voltage amplification.
transmission line 1. A single conductor or group
of conductors for carrying electrical energy from
one point to another. 2. A correctly dimensioned
conductor or pair of conductors for carrying radio-frequency
energy from a transmitter to an antenna
or coupling device.
transmission mode 1. In a transceiver, the condition
in which the transmitter is enabled and the
receiver is disabled. 2. In a waveguide, propagation
via transverse waves.
transmission speed The number of information elements
(words, code groups, data symbols, bits,
and bytes) that can be generated or received per
unit time (second or minute) by a system or operator.
transmission wavemeter A (usually simple) inductance-capacitance-tuned
wavemeter that provides
peak response when tuned to the frequency
of a signal passing through it; also, the comparable
microwave device. Compare ABSORPTION
WAVEMETER.
transmit-receive switch A manually or electrically
operated switch for transferring a single antenna
between a transmitter and receiver.
transmittancy The relative ability of a substance
to transmit radiation. Transmittancy depends on
the frequency of the radiation, as well as the substance.
transmitter 1. An equipment for producing and
sending signals or data. 2. See MICROPHONE. 3.
One who originates signals or data.
transmitter–receiver A transmitter and receiver
usually contained in a single enclosure, but with
separate and independent oscillators, mixers,
and amplifiers. The main asset of this scheme is
the fact that it is possible to conduct splitfrequency
communication on bands whose wavelengths
differ greatly. Another asset is the ability
of the system, with proper design, to operate in
full-duplex mode. Installations of this type are often
used in satellite communications. Compare
TRANSCEIVER, 1.
transmitting antenna An antenna designed expressly
for the efficient radiation of electromagnetic
energy into space.
transmitting station A station that only transmits
signals (i.e., it engages in no official form of reception).
Compare RECEIVING STATION.
transmittivity The degree to which a selective circuit
transmits a desired signal. Compare REJEC-
TIVITY.
transmultiplexer A device that changes a signal
from one multiplexed form to another while maintaining
all of the information contained in the signal.
For example, a transmultiplexer might
convert time-division-multiplex data to frequency-division
multiplex or vice-versa.
transonic Equal to, or approximating, the speed of
sound in air (approximately 1100 feet per second).
transparence The practically unimpeded transmission
of radiation, such as light, through a material.
Compare OPACITY and TRANSLUCENCE.
transponder An acronym for transmitter and
responder. 1. A combination transmitter–receiver
that automatically transmits an identification
signal whenever it receives an interrogating signal.
2. In a communications satellite, a broadband
repeater that receives signals sent up from
the earth, converts them to another frequency,
and retransmits them back to the earth. Some
satellites have units that employ multiplexing,
data storage and retrieval systems, and other
schemes to maximize the amount and variety of
data they can handle.
transponder overload A condition that occurs
when a satellite transponder is heavily used or
when an excessively strong uplink signal is received.
During heavy usage, all downlink signals
are consistently weaker than they are when the
transponder is not dealing with many signals. If
an overly powerful uplink signal is received, all
downlink signals are attenuated intermittently;
the greater the instantaneous power of the offending
uplink signal, the greater the instantaneous
attenuation of all the downlink signals.
See TRANSPONDER, 2.
transport See TAPE TRANSPORT.
transportable equipment Portable electronic
equipment. See, for example, PORTABLE TRANS-
MITTER.
transuranium An element whose atomic number
is higher than that of uranium.
transverse Occurring in a direction or directions
perpendicular to the direction of propagation.