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ASYMMETRICAL MULTIVIBRATOR—A multivibrator that generates rectangular waves [18].
ASYNCHRONOUS—The teletypewriter operation where the transmitter and receiver do not operate
continuously [17].
ASYNCHRONOUS ORBIT—One where the satellite does not rotate or move at the same speed as the
earth [17].
ATDS—An abbreviation for the airborne tactical data system [17].
ATTENUATION—The ability of a filter circuit to reduce the amplitude of unwanted frequencies to a level
below that of the desired output frequency [9].
ATTRACTION—The force that tends to make two objects approach each other. Attraction exists between
two unlike magnetic poles (north and south) or between two unlike static charges [1].
AUDIO AMPLIFIER—An amplifier designed to amplify frequencies between 15 hertz (15 Hz) and 20
kilohertz (20 kHz) [8].
AUDIO-FREQUENCY-TONE SHIFT—A system that uses amplitude modulation to change dc mark and
space impulses into audio impulses [17].
AUTOMATIC GAIN CONTROL—A circuit used to vary radar receiver gain for best reception of signals
that have widely varying amplitudes [18].
AUTOMATIC TRACKING—Tracking done by equipment that compares the direction of the antenna axis
and the direction of the received signal and uses the difference (error) signal to reposition the antenna
[17].
AUTOMATIC VOLUME/GAIN CONTROL—A circuit used to limit variations in the output signal
strength of a receiver [17].
AVALANCHE EFFECT—A reverse breakdown effect in diodes that occurs at reverse voltages beyond 5
volts. The released electrons are accelerated by the electric field, which results in a release of more
electrons in a chain or "avalanche" effect [7].
AVERAGE POWER—(1) The peak power value averaged over the pulse-repetition time [12]. (2) Output
power of a transmitter as measured from the start of one pulse to the start of the next pulse [18].
AVERAGE VALUE (OF AC)—The average of all the instantaneous values of one-half cycle of alternating
current [2].
AXIS—A straight line, either real or imaginary, passing through a body around which the body revolves
[15].
AZIMUTH—Angular measurement in the horizontal plane in a clockwise direction [18].
BACK RESISTANCE—The larger resistance value observed when you are checking the resistance of a
semiconductor [16].
BALANCED MIXER—A waveguide arrangement that resembles a T and uses crystals for coupling the
output to a balanced transformer [18].
BALANCED PHASE DETECTOR—A circuit that controls the oscillator frequency (afc) [17].
