## Electronics (Mike Jaroch)

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### R

An acronym for RAdio Detecting And Ranging [18].

Airborne radar that measures the distance of the aircraft above the ground [18].

The space in front of a radar antenna where a target can be effectively detected or tracked. Defined by areas that contain half or more of the maximum power transmitted [18].

A detector that, in its simplest form, only needs to be capable of producing an
output when RF energy (reflected from a target) is present at its input [12].

An electrical switching panel used to connect inputs from any of several radars to repeaters (indicators) [18].

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 [18].

A combination of several test circuits and equipment used to test various

The electromagnetic field that radiates from an antenna and travels through space [10].

The losses that occur when magnetic lines of force about a conductor are
projected into space as radiation and are not returned to the conductor as the cycle alternates [10].

A plot of the radiated energy from an antenna [10].

The resistance that if inserted in place of the antenna would consume the
same amount of power as that radiated by the antenna [10].

The term describing teletypewriter, voice, telegraphic, and facsimile
communications. [17].

RADIO FREQUENCY (RF)—(1) Any frequency of electromagnetic energy capable of propagation into space [2]. (2) The frequencies that fall between 3 kilohertz and 300 gigahertz used for radio communications [10].

The system that uses a keyer to shift a radio frequency signal above or below an assigned frequency. These shifts correspond to marks and spaces [17].

The boundary beyond the natural horizon in which radio waves cannot be propagated over the earth's surface [10].

Equipment used to remotely control certain transmitter and receiver
functions [17].

(1) A form of radiant energy that can neither be seen nor felt. (2) An electromagnetic wave that is generated by a transmitter [10].

Also called the base. The number of distinct symbols used in a number system. For example, since the decimal number system uses ten symbols (0, 1, 2, 3, 4, 5, 6, 7, 8, 9), the radix is 10. In the binary number system, the radix is 2 because it uses only two symbols (0, 1) [13].

Also called BINARY POINT, OCTAL POINT, DECIMAL POINT, and so forth, depending on the number system [13].

#### RANGE

The length of a straight line between a radar set and a target [11] [18].
 Keyword(s): RANGE

#### 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].

 Keyword(s): RANGE MARKER

#### RANGE RESOLUTION

Ability of a radar to distinguish between targets that are close together [18].
 Keyword(s): RANGE RESOLUTION

#### RANGE STEP

On an A-scope sweep, a vertical displacement used to measure the range of an echo [18].
 Keyword(s): RANGE STEP

#### RANGE-GATE

A movable gate used to select radar echoes from a very short range interval [18].
 Keyword(s): RANGE-GATE

#### RANGE-HEIGHT INDICATOR

A radar display on which slant range is shown along the X axis and height along the Y axis [18].

 Keyword(s): RANGE-HEIGHT INDICATOR

#### 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].

 Keyword(s): RANGES

#### RAREFIED WAVE

A longitudinal wave that has been expanded or rarefied (made less dense) as it
moves away from the source [10].

 Keyword(s): RAREFIED WAVE

#### RATE GYRO

A gyro used to detect and measure angular rates of change [15].
 Keyword(s): RATE GYRO

#### RATIO

The value obtained when one number is divided by another. This value indicates the relative proportions of the two numbers [2].

 Keyword(s): RATIO

#### 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].

 Keyword(s): RATIO OF TRANSMITTED POWERS

#### 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].

 Keyword(s): RC CONSTANT

#### RC DIFFERENTIATOR

An RC circuit in which the output is taken from the resistor [9].
 Keyword(s): RC DIFFERENTIATOR

#### RC FILTER

A filter used in applications where load current is low and constant, and voltage regulation is not necessary [7].

 Keyword(s): RC FILTER

#### RC INTEGRATOR

An RC circuit in which the output is taken from the capacitor [9].
 Keyword(s): RC INTEGRATOR

#### RC NETWORK

A circuit containing resistance and capacitance arranged in a particular manner to perform a specific function [9].

 Keyword(s): RC NETWORK

#### RC OSCILLATOR

An oscillator in which the frequency is determined by resistive and capacitive
elements [9].

 Keyword(s): RC OSCILLATOR

#### REACTANCE

The opposition offered to the flow of an alternating current by the inductance,
capacitance, or both, in any circuit [2].

 Keyword(s): REACTANCE

#### 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].

 Keyword(s): REACTANCE AMPLIFIER

#### 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].

 Keyword(s): REACTANCE TUBE

#### REACTANCE-TUBE MODULATOR

An FM modulator that uses a reactance tube in parallel with the oscillator tank circuit [12].

 Keyword(s): REACTANCE-TUBE MODULATOR

(1) The object that responds to the wave or disturbance. Same as DETECTOR [10]. (2) Equipment that converts electromagnetic energy into a visible or an audible form [17]. (3) In radar, a unit that converts RF echoes to video and/or audio signals [18].

(1) The degree to which a receiver can usefully detect a weak signal. (2)
The lower limit of useful signal input to the receiver [18].

Equipment used to transfer receiver audio outputs to remote control station audio circuits [17].

#### RECEIVING ANTENNA

The device used to pick up the RF signal from space [10].
 Keyword(s): RECEIVING ANTENNA

#### RECEIVING END

See OUTPUT END [10].
 Keyword(s): RECEIVING END

#### RECEPTION

The instant when an electromagnetic wave passes through a receiver antenna and induces a voltage in that antenna [17].

 Keyword(s): RECEPTION

#### RECIPROCAL

(OF A QUANTITY)—The value obtained by dividing the number 1 by that quantity [1].
 Keyword(s): RECIPROCAL

#### RECIPROCITY

The property of interchangeability of the same antenna for transmitting and receiving [10] [11].

 Keyword(s): RECIPROCITY

#### 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 [18].

 Keyword(s): RECOVERY TIME

#### RECTANGULAR-COORDINATE GRAPH

A graph in which straight-line axes (horizontal and vertical) are perpendicular [10].

 Keyword(s): RECTANGULAR-COORDINATE GRAPH

#### RECTIFIER

A device used to convert ac to pulsating dc [3] [6] [7].
 Keyword(s): RECTIFIER

#### RED

The reference color of equipment that passes classified information. It normally refers to patch panels [17].

 Keyword(s): RED

#### REFERENCE LINE

The position of zero displacement in a wave [10].
 Keyword(s): REFERENCE LINE

#### REFERENCE POINT

A point in a circuit to which all other points in the circuit are compared [1].
 Keyword(s): REFERENCE POINT

#### REFLECTED WAVE

(1) The wave that reflects back from a medium. (2) The wave moving back to the source from the termination of a transmission line after reflection has occurred [10].

 Keyword(s): REFLECTED WAVE

#### REFLECTING OBJECT

In radar a air or surface contact that provides an echo [18].
 Keyword(s): REFLECTING OBJECT

#### REFLECTION WAVES

Waves that are neither transmitted nor absorbed, but are reflected from the
surface of the medium they encounter [10].

 Keyword(s): REFLECTION WAVES

#### REFLECTOR

The parasitic element of an array that causes maximum energy radiation in a direction toward the driven element [10].

 Keyword(s): REFLECTOR

#### REFLEX KLYSTRON

A klystron with a reflector (repeller) electrode in the place of a second resonant cavity used to redirect the velocity-modulated electrons back through the cavity that produced the modulation [11]. (2) A microwave oscillator that is tuned by changing the repealer voltage [18].

 Keyword(s): REFLEX KLYSTRON

#### REFRACTION

The changing of direction of a wave as it leaves one medium and enters another medium of a different density [10] [18].

 Keyword(s): REFRACTION

#### REFRACTIVE INDEX

In a wave-transmission medium, the ratio between the phase velocity in free
space and in the medium [11] [18].

 Keyword(s): REFRACTIVE INDEX

#### REGENERATION

See FEEDBACK [18].
 Keyword(s): REGENERATION

#### REGENERATIVE DETECTOR

A detector circuit that produces its own oscillations, heterodynes them
with an incoming signal, and deflects them [12].

 Keyword(s): REGENERATIVE DETECTOR

#### REGENERATIVE FEEDBACK

The process by which a portion of the output signal of an amplifying
device is fed back in phase to reinforce the input. Also called POSITIVE FEEDBACK [8] [9].

 Keyword(s): REGENERATIVE FEEDBACK

#### REGULATOR

The section in a basic power supply that maintains the output of the power supply at a constant level in spite of large changes in load current or input line voltage [6] [7].

 Keyword(s): REGULATOR

#### RELATIVE BEARING

Bearing of a target measured in a clockwise direction from "dead ahead" of a
ship or plane [18].

 Keyword(s): RELATIVE BEARING

#### RELAY

An electromagnetic device with one or more sets of contacts that change position by the magnetic attraction of a coil to an armature [3].

 Keyword(s): RELAY

#### RELUCTANCE

A measure of the opposition that a material offers to magnetic lines of force [1].
 Keyword(s): RELUCTANCE

#### REMOTE-CUTOFF TUBE

An electron tube in which the control grid wires are farther apart at the
centers than at the ends. This arrangement allows the tube to amplify large signals without being driven into cutoff. This tube is also called a VARIABLE-MU TUBE [6].

 Keyword(s): REMOTE-CUTOFF TUBE

#### REPEATER

(1) Another name for an active satellite [17]. (2) Also, a common name for remote radar indicators.

 Keyword(s): REPEATER

#### REPELLER

Sometimes called a REFLECTOR. An electrode in a reflex klystron with the primary purpose of reversing the direction of the electron beam [11].

 Keyword(s): REPELLER

#### REPERFORATOR

Equipment that converts the incoming TTY signal and stores it on paper tape [17].
 Keyword(s): REPERFORATOR

#### REPRODUCTION

The process of converting electrical signals to sound waves. This sound is speech, music, and so on [17].

 Keyword(s): REPRODUCTION

#### REPULSION

The mechanical force tending to separate bodies having like electrical charges or like magnetic polarity [1].

 Keyword(s): REPULSION

The reception and retransmission of radio waves that is caused by turbulence in the troposphere [10].

#### RESIDUAL MAGNETISM

Magnetism remaining in a substance after removal of the magnetizing force
[1].

 Keyword(s): RESIDUAL MAGNETISM

#### RESISTANCE

(1) The opposition a device or material offers to the flow of current. The effect of resistance is to raise the temperature of the material or device carrying the current. (2) A circuit element designed to offer a predetermined resistance to current flow. A resistance of 1 ohm will allow a current of 1 ampere to flow through it when a potential of 1 volt is applied. [1].

 Keyword(s): RESISTANCE

#### RESISTIVITY

See SPECIFIC RESISTANCE. The reciprocal of conductivity [4].
 Keyword(s): RESISTIVITY

#### RESISTOR

The electrical component that offers resistance to the flow of current. It may be a coil of fine wire or a composition rod [1].

 Keyword(s): RESISTOR

#### RESOLVER

A rotary, electromechanical device used to perform trigonometric computations by varying the magnetic couplings between its primary and secondary windings. It is generally used in circuits that solve vector problems, such as analog computers and conversion equipment. The resolver solves three different type problems: (1) Resolution - separating a vector into two mutually perpendicular
components; (2) Composition - combining two components of a vector to produce a vector sum; and (3) Combination - the process of resolution and composition taking place simultaneously [15].

 Keyword(s): RESOLVER

#### RESONANCE

The condition in a circuit containing inductance and capacitance in which the inductive reactance is equal and opposite to the capacitive reactance. This condition occurs at only one frequency and the circuit in that condition is said to be in resonance [2] [9] [10].

 Keyword(s): RESONANCE

#### RESONANCE CHAMBER

See ECHO BOX [18].
 Keyword(s): RESONANCE CHAMBER

#### RESONANT CIRCUIT

A circuit that contains both inductance and capacitance and is resonant at one
frequency (XL = XC) [9].

 Keyword(s): RESONANT CIRCUIT

#### RESONANT FREQUENCY

That frequency in a given resonant circuit at which the inductive and
capacitive reactance values are equal and cancel each other [9].

 Keyword(s): RESONANT FREQUENCY

#### RESONANT LINE

A transmission line that has standing waves of current and voltage [10].
 Keyword(s): RESONANT LINE

#### REST FREQUENCY

The carrier frequency during the constant-amplitude portions of a phase
modulation signal [12].

 Keyword(s): REST FREQUENCY

#### REST POSITION

See REFERENCE LINE [10].
 Keyword(s): REST POSITION

#### REST TIME

(RT)—The time when there is no pulse; nonpulse time [12].
 Keyword(s): REST TIME , RT

#### RESULTANT MAGNETIC FIELD

The magnetic field produced in a synchro by the combined effects of the three stator magnetic fields [15].

 Keyword(s): RESULTANT MAGNETIC FIELD

#### RETENTIVITY

The ability of a material to retain its magnetism [1].
 Keyword(s): RETENTIVITY

#### RETURN

The RF signal reflected back from a radar target; echo [18].
 Keyword(s): RETURN

#### REVERBERATION

The multiple reflections of sound waves [10].
 Keyword(s): REVERBERATION

#### REVERSE AGC

The type of AGC that causes an amplifier to be driven toward cut-off [17].
 Keyword(s): REVERSE AGC

#### REVERSE BIAS

An external voltage applied to a diode or semiconductor junction to reduce the flow of electrons across the junction. Also called BACK BIAS [7] [13].

 Keyword(s): REVERSE BIAS

#### RF AMPLIFIER

RF (RADIO FREQUENCY) AMPLIFIER—An amplifier designed to amplify signals with frequencies between 10 kilohertz (10 kHz) and 100,000 megahertz (100,000 MHz) [8].

 Keyword(s): RF AMPLIFIER

A health hazard caused by exposure to electromagnetic radiation or high-
energy particles (ions). Abbreviated RADHAZ [18].

#### RF TRANSFORMER

RF (RADIO FREQUENCY) TRANSFORMER—A transformer specially designed for use with RF (radio frequencies). An RF transformer is wound onto a tube of nonmagnetic material and has a core of either powdered iron or air [8].

 Keyword(s): RF TRANSFORMER

#### RGK

The symbol used to express the resistance between the grid and the cathode of an electron tube [6].
 Keyword(s): RGK

#### RHEOSTAT

A variable resistor used for the purpose of adjusting the current in a circuit [1] [4].
 Keyword(s): RHEOSTAT

#### RHO

Greek letter "rho" (ρ). Used in the field of electricity and electronics to represent the specific resistance of a substance [4].

 Keyword(s): RHO

#### RHOMBIC ANTENNA

A diamond-shaped antenna used widely for long-distance, high-frequency
transmission and reception [10].

 Keyword(s): RHOMBIC ANTENNA

#### RIGID COAXIAL LINE

A coaxial line consisting of a central insulated wire (inner conductor) mounted
inside of a tubular outer conductor [10].

 Keyword(s): RIGID COAXIAL LINE

#### RIGIDITY

The tendency of the spin axis of a gyro wheel to remain in a fixed direction in space if no force is applied to it [15].

 Keyword(s): RIGIDITY

#### RING TIME

In radar, the time during which the output of an echo box remains above a specified level [18].

 Keyword(s): RING TIME

#### RINGING

RF oscillations caused by shock excitation of a resonant circuit or cavity [18].
 Keyword(s): RINGING

#### RIPPLE FREQUENCY

The frequency of the ripple current. In a full-wave rectifier it is twice the input-line frequency [6].

 Keyword(s): RIPPLE FREQUENCY

#### RIPPLE VOLTAGE

The alternating component of unidirectional voltage. (This component is small
compared to the direct component.) [6]

 Keyword(s): RIPPLE VOLTAGE

#### RL DIFFERENTIATOR

An RL circuit in which the output is taken from the inductor [9].
 Keyword(s): RL DIFFERENTIATOR

#### RL INTEGRATOR

An RL circuit in which the output is taken from the resistor [9].
 Keyword(s): RL INTEGRATOR

#### RLC CIRCUIT

An electrical circuit that has the properties of resistance, inductance, and capacitance [2].
 Keyword(s): RLC CIRCUIT

#### RMS

Abbreviation of root mean square [2].
 Keyword(s): RMS

#### ROOT MEAN SQUARE

(RMS)—The equivalent heating value of an alternating current or voltage, as
compared to a direct current or voltage. It is 0.707 times the peak value of a sine wave [2].

 Keyword(s): ROOT MEAN SQUARE , RMS

#### ROTARY CAP

A spark gap, similar to a mechanically driven rotary switch, used to discharge a pulse-forming network [12].

 Keyword(s): ROTARY CAP

#### ROTARY SWITCH

A multicontact switch with contacts arranged in a circular or semicircular manner [3].

 Keyword(s): ROTARY SWITCH

#### ROTATING FIELD

The magnetic field in a multiphase ac motor that is the result of field windings being energized by out-of-phase currents. In effect, the magnetic field is made to rotate electrically rather than mechanically [5].

 Keyword(s): ROTATING FIELD

#### ROTATING JOINT

A joint that permits one section of a transmission line or waveguide to rotate
continuously with respect to another while passing energy through the joint. Also called a rotary coupler [11].

 Keyword(s): ROTATING JOINT

#### ROTOR

(1) The revolving part of a rotating electrical machine. The rotor may be either the field or the armature, depending on the design of the machine [5]. (2) The rotating member of a synchro that consists of one or more coils of wire wound on a laminated core. Depending on the type of synchro, the rotor functions similarly to the primary or secondary winding of a transformer [15].

 Keyword(s): ROTOR

#### RPK

The symbol used to represent the resistance between the cathode and plate of a tube [6].
 Keyword(s): RPK

#### RUNNING OPEN

The teletypewriter condition where the type hammer constantly strikes the type box but does not print or move across the page [17].

 Keyword(s): RUNNING OPEN

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