AI-4
NEAR SYNCHRONOUS ORBIT—An orbit in which the satellite rotates close to but not exactly at the
same speed as the earth.
NEUTRAL—The teletypewriter operation where current flow represents a mark and no flow represents a
space.
NOISE SILENCER, NOISE SUPPRESSOR, OR NOISE LIMITER—Circuits that clip the peaks of
the noise spikes in a receiver.
NONSYNCHRONOUS—The teletypewriter operation where both transmitter and receiver do not
operate continuously
ORDER-WIRE CIRCUIT—A circuit between operators used for operations control and coordination.
PAGE PRINTER—A high-speed printer that prints teletypewriter characters one at a time in a full-page
format.
PASSIVE SATELLITE—A satellite that reflects radio signals back to earth.
PATCH PANEL—A panel used to tie a receiver or transmitter to its associated equipment.
PART—A part is one component or two or more components joined together. It is not normally subject
to disassembly without destruction.
PERFORATOR—A device that stores a teletypewriter message on a paper tape. It may be stored for
later transmission.
PERIGEE—The point in the orbit of a satellite closest to the earth.
PERMANENT MAGNET SPEAKER—A speaker with a permanent magnet mounted on soft iron pole
pieces.
POLAR—The teletypewriter operation where current flow of one polarity represents a mark and current
of the opposite polarity represents a space.
POLAR ORBIT—An orbit that has an angle of inclination of or near 90 degrees.
PROGRAMMED TRACKING—The method that uses known satellite orbital parameters to generate
antenna pointing angles.
RADIO COMMUNICATIONS—The term describing teletypewriter, voice, telegraphic, and facsimile
communications.
RADIO FREQUENCY CARRIER SHIFT—The system that uses a keyer to shift a radio frequency
signal above or below an assigned frequency. These shifts correspond to marks and spaces.
RADIO SET CONTROL UNIT—Equipment used to remotely control certain transmitter and receiver
functions.
RECEIVER—Equipment that converts electromagnetic energy into a visible or an audible form.
RECEIVER TRANSFER SWITCHBOARD—Equipment used to transfer receiver audio outputs to
remote control station audio circuits.
