1-60
RANGE-HEIGHT INDICATOR—A radar display on which slant range is shown along the X axis and
height along the Y axis [18].
RANGE MARKER—A movable vertical pulse on an A-scope or a ring on a PPI scope used to measure the
range of an echo or to calibrate the range scale [18].
RANGE RESOLUTION—Ability of a radar to distinguish between targets that are close together [18].
RANGES—The several upper limits a meter will measure as selectable by a switch or by jacks; for
example, a voltmeter may have ranges of 1 volt, 2.5 volts, 10 volts, 25 volts, and 100 volts [3].
RANGE STEP—On an A-scope sweep, a vertical displacement used to measure the range of an echo [18].
RAREFIED WAVE—A longitudinal wave that has been expanded or rarefied (made less dense) as it
moves away from the source [10].
RATE GYRO—A gyro used to detect and measure angular rates of change [15].
RATIO—The value obtained when one number is divided by another. This value indicates the relative
proportions of the two numbers [2].
RATIO DETECTOR—A detector that uses a double-tuned transformer to convert the instantaneous
frequency variations of the FM input signal to instantaneous amplitude variations [12].
RATIO OF TRANSMITTED POWERS—The power ratio (FSK versus AM) that expresses the overall
improvement of FSK transmission when compared to AM under rapid-fading and high-noise conditions
[12].
RC CONSTANT—Time constant of a resistor-capacitor circuit; equal in seconds to the resistance value in
ohms multiplied by the capacitance value in farads [2] [9].
RC DIFFERENTIATOR—An RC circuit in which the output is taken from the resistor [9].
RC FILTER—A filter used in applications where load current is low and constant, and voltage regulation is
not necessary [7].
RC INTEGRATOR—An RC circuit in which the output is taken from the capacitor [9].
RC NETWORK—A circuit containing resistance and capacitance arranged in a particular manner to
perform a specific function [9].
RC OSCILLATOR—An oscillator in which the frequency is determined by resistive and capacitive
elements [9].
REACTANCE—The opposition offered to the flow of an alternating current by the inductance,
capacitance, or both, in any circuit [2].
REACTANCE AMPLIFIER—A low-noise amplifier that uses a nonlinear variable reactance as the active
element instead of a variable resistance. Also called a parametric amplifier [11].
REACTANCE TUBE—A tube connected in parallel with the tank circuit of an oscillator. Provides a signal
that will either lag or lead the signal produced by the tank [12].
REACTANCE-TUBE MODULATOR—An FM modulator that uses a reactance tube in parallel with the
oscillator tank circuit [12].
