RADAR DISTRIBUTION SWITCHBOARDAn electrical switching panel used to connect inputs
from any of several radars to repeaters.
RADAR MILETime 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 SETCombination of several test circuits and equipment used to test various
characteristics of a radar.
RANGEThe length of a straight line between a radar set and a target.
RANGE-HEIGHT INDICATORA radar display on which slant range is shown along the X axis and
height along the Y axis.
RANGE-GATEA movable gate used to select radar echoes from a very short-range interval.
RANGE MARKERA 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 RESOLUTIONAbility of a radar to distinguish between targets that are close together.
RANGE STEPOn an A-scope sweep, vertical displacement used to measure the range of an echo.
RECEIVERIn radar, a unit that converts rf echoes to video and/or audio signals.
RECEIVER SENSITIVITYThe degree to which a receiver can usefully detect a weak signal; the
lower limit of useful signal input to the receiver.
RECOVERY TIMEIn 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 OBJECTIn radar, an air or surface contact that provides an echo.
REFLEX KLYSTRONA microwave oscillator that is tuned by changing the repeller voltage.
REFRACTIONThe bending of rf waves as the waves pass through mediums of different density.
REFRACTIVE INDEXIn a wave-transmission medium, the ratio between the phase velocity in free
space and in the medium.
RELATIVE BEARINGBearing of target measured in a clockwise direction from "dead ahead" of a
ship or plane.
RESONANCE CHAMBERSee Echo Box.
RETURNThe rf signal reflected back from a radar target; echo.
RF RADIATION HAZARDHealth hazard caused by exposure to electromagnetic radiation or high-
energy particles (ions). Abbreviated RADHAZ.
RING TIMEIn radar, the time during which the output of an echo box remains above a specified level.
RINGINGRf oscillations caused by shock excitation of a resonant circuit (cavity).