COMPARATORAn equipment that compares incoming signals and selects the strongest to be fed to a
teletypewriter through a patch panel. This is used in diversity operation.
CONVERTERAn equipment that changes the audio output of a receiver to dc pulses. These pulses are
fed to a tty to indicate marks and spaces.
DETECTIONThe separation of low-frequency (audio) intelligence from the high (radio) frequency
DOUBLING UPThis is a type of two-equipment installation where one unit can be substituted for
another in the event of failure.
DOWN LINKThe frequency used to transmit an amplified signal from the satellite back to earth.
DUMMY LOADA nonradiating device that absorbs the rf and has the impedance characteristics of the
ECLIPSEThis occurs when the satellite is not in view or in direct line of sight with the sun. This
happens when the earth is between them.
ELECTROMAGNETIC INTERFERENCEA term used to describe the degradation of a receiver or
EPHEMERISA table showing the precalculated position of a satellite at any given time.
EQUATORIAL ORBITAn orbit that occurs when the plane of a satellite coincides with the plane of
the earth at the equator.
EXTREMELY HIGH FREQUENCYThe band of frequencies from 30 gigahertz to 300 gigahertz.
EXTREMELY LOW FREQUENCYThe band of frequencies up to 300 hertz.
FACSIMILEThe method for transmitting and receiving still images. These images can be maps,
photographs, and handwritten or printed text.
FADINGThe variations in signal strength at the antenna of a receiver.
FIBER OPTICSConductors or optical waveguides that readily pass light.
FIDELITYThe ability of a receiver to accurately reproduce, at its output, the signal at its input.
FORWARD AGCThe type of agc that causes an amplifier to be driven towards saturation.
FRAMINGThe process of synchronizing a facsimile receiver to a transmitter. This allows proper
FREQUENCY-DIVISION MULTIPLEXINGMultiplexing that transmits and receives the full 360
degrees of each sine wave.
FREQUENCY SYNTHESISA process that uses hetrodyning and frequency selection to produce a
FREQUENCY SYNTHESIZERA frequency source of high accuracy.
GANGED TUNINGThe process used to tune two or more circuits with a single control.