AI-6
MASTER OSCILLATOR—In a transmitter, the oscillator that establishes the carrier frequency of the
output.
MECHANICAL SCANNING—The reflector, its feed source, or the entire antenna is moved in a desired
pattern.
MINIMUM DISCERNIBLE SIGNAL (MDS)—The weakest signal that produces a usable signal at the
output of a receiver. The weaker the signal, the more sensitive the receiver.
MIXER—In radar, a circuit that combines the received rf signal with a local-oscillator signal to
effectively convert the received signal to a lower IF frequency signal.
MODE SHIFTING—In a magnetron, shifting from one mode to another during a pulse.
MODE SKIPPING—Rather than firing on each successive pulse as desired, the magnetron fires
randomly.
MODES—Operational phases (of a radar).
MODULATOR SWITCHING DEVICE—Controls the on (discharge) and off (charge) time of the
modulator.
MODULATOR—Produces a high-voltage pulse that turns the transmitter on and off.
MONOPULSE (SIMULTANEOUS) LOBING—Radar receiving method using two or more (usually
four) partially overlapping lobes. Sum and difference channels locate the target with respect to the
axis of the antenna.
MONOPULSE RADAR—A radar that gets the range, bearing, and elevation position data of a target
from a single pulse.
MONOPULSE RECEIVER—See Monopulse Lobing.
MOISTURE LAPSE—Abnormal variation of moisture content at different altitudes because of high
moisture located just above large bodies of water.
MOVING TARGET INDICATOR—A device that limits the display of radar information to moving
targets.
NAUTICAL MILE—The length of a minute of arc of a great circle of the earth (6,076 ft.)
NAUTICAL RADAR MILE—See Radar Mile.
NOISE—In radar, erratic or random deflection or intensity of the indicator sweep that tends to mask
small echo signals.
NOISE FIGURE—The ratio of output noise to input noise in a receiver.
NUTATING—Moving an antenna feed point in a conical pattern so that the polarization of the beam
does not change.
OMNIDIRECTIONAL ANTENNA—An antenna that radiates equally in all directions (nondirectional).
ORANGE-PEEL PARABOLOID—A section of a complete circular paraboloid that is narrow in the
horizontal plane and wide in the vertical plane.
