AI-8
RADAR DISTRIBUTION SWITCHBOARD—An electrical switching panel used to connect inputs
from any of several radars to repeaters.
RADAR MILE—Time interval (12.36 microseconds) for rf energy to travel out from a radar to a target
and back to the radar; radar nautical mile.
RADAR TEST SET—Combination of several test circuits and equipment used to test various
characteristics of a radar.
RANGE—The length of a straight line between a radar set and a target.
RANGE-HEIGHT INDICATOR—A radar display on which slant range is shown along the X axis and
height along the Y axis.
RANGE-GATE—A movable gate used to select radar echoes from a very short-range interval.
RANGE MARKER—A movable vertical pulse on an A-scope or ring on a ppi scope used to measure
the range of an echo or to calibrate the range scale.
RANGE RESOLUTION—Ability of a radar to distinguish between targets that are close together.
RANGE STEP—On an A-scope sweep, vertical displacement used to measure the range of an echo.
RECEIVER—In radar, a unit that converts rf echoes to video and/or audio signals.
RECEIVER SENSITIVITY—The degree to which a receiver can usefully detect a weak signal; the
lower limit of useful signal input to the receiver.
RECOVERY TIME—In a radar, the time interval between the end of the transmitted pulse and the time
when echo signals are no longer attenuated by the tr gap.
REFLECTING OBJECT—In radar, an air or surface contact that provides an echo.
REFLEX KLYSTRON—A microwave oscillator that is tuned by changing the repeller voltage.
REFRACTION—The bending of rf waves as the waves pass through mediums of different density.
REFRACTIVE INDEX—In a wave-transmission medium, the ratio between the phase velocity in free
space and in the medium.
REGENERATION—See Feedback.
RELATIVE BEARING—Bearing of target measured in a clockwise direction from "dead ahead" of a
ship or plane.
RESONANCE CHAMBER—See Echo Box.
RETURN—The rf signal reflected back from a radar target; echo.
RF RADIATION HAZARD—Health hazard caused by exposure to electromagnetic radiation or high-
energy particles (ions). Abbreviated RADHAZ.
RING TIME—In radar, the time during which the output of an echo box remains above a specified level.
RINGING—Rf oscillations caused by shock excitation of a resonant circuit (cavity).
