AI-6
SYNCHRONOUS ORBIT—An orbit in which the satellite moves or rotates at the same speed as the
earth.
SYSTEM—A combination of sets, units, assemblies, subassemblies, and parts joined together to form a
specific operational function or several functions.
TELECOMMUNICATIONS—The transmission, emission, or reception of signs, signals, writings,
images, or sounds. This is done by visual, oral, wire, radio, or other electromagnetic means.
TELETYPEWRITER—A machine that can transmit and or receive letters, numbers, or symbols. It may
have a keyboard similar to a typewriter.
TEMPEST—A term normally used to describe compromising emanations. These emanations are
unintentionally radiated signals that could disclose classified information.
TIME-DIVISION MULTIPLEXING—The process that periodically samples the full 360 degrees of
each sine wave. The sample can be of a received signal or of a signal to be transmitted.
TONE-TERMINAL SET—Equipment that converts tty dc pulses into audio tones for modulation of a
transmitter in audio-frequency-tone shift transmissions.
TOP-HAT—An antenna that is center-fed and capacitively loaded.
TRANSITION—The time it takes to shift from a mark to a space condition or from a space to a mark
condition.
TRANSMITTER—Equipment that generates and amplifies an rf carrier, modulates the rf carrier with
intelligence, and radiates the signal into space.
TRANSMITTER DISTRIBUTOR—A device that reads Baudot code from paper tape and allows a
message to be printed on a page printer.
TRANSMITTER TRANSFER SWITCHBOARD—Equipment that selectively transfers remote control
station functions and signals to transmitters.
TRIATIC—A special type of monopole antenna array.
ULTRAHIGH FREQUENCY—The band of frequencies from 300 megahertz to 3 gigahertz.
UNIT—An assembly or any combination of parts, subassemblies, and assemblies mounted together.
Normally capable of independent operation.
UP LINK—The frequency used to transmit a signal from earth to a satellite.
VERY HIGH FREQUENCY—The band of frequencies from 30 megahertz to 300 megahertz.
VERY LOW FREQUENCY—The band of frequencies from 3 kilohertz to 30 kilohertz.
WORDS-PER-MINUTE—An approximate rate of speed. It means the number of five letter words with
a space between them that can be transmitted or received in a one-minute period.
ZONE OF MUTUAL VISIBILITY—The area where the satellite can be seen by both the up- and
down-link earth terminals.
