Glossary / Technology

Radar Glossary

Absorption: The process, in which incident radiated energy is retained by the medium without being reflected or
Aerial: Antenna.
Afterglow: The slowly decaying luminescence of the screen of the cathode-ray tube after excitation by an electr
Airborne Radar: An airborne radar is carried by an aircraft.
Airborne Warning and Control System (AWACS): The AWACS is a system mounted in a boeing e3 aircraft that provides airborne surveillance and comman
Airport Radar: Airport radar provides information to air traffic controllers on aircraft in the local air space.
Amplify: To increase the strength of a radar signal or echo.
Antenna: A conductor or system of conductors consisting of horn and reflector used for radiating or receiving
Anti-Clutter Control: A means for reducing or eliminating interferences from sea return and weather.
Anti-Clutter Rain Control: An electronic circuit that suppresses the reflected radar energy from rain and other forms of precip
Anti-Clutter Sea Control: An electronic circuit that suppresses clutter caused by the reflection of echoes from waves in a sea
Anti-Radiation Missile (ARM): An anti-radiation missile is able to guide itself to destroy a radar using the signal transmitted by
Attenuation: The decrease in the strength of a radar wave resulting from absorption, scattering, and reflection b
Automatic Frequency Control (AFC): An electronic means for preventing drift in radio frequency or maintaining the frequency within spec
Azimuth: While this term is frequently used for bearing in radar applications, the term azimuth is usually re
Barrage Jamming: Barrage jamming is used when there is a need to jam over a wide bandwidth simultaneously. Barrage ja
Beam Width: The angular width of a radar beam between half-power points. See lobe.
Bearing: The direction of the line of sight from the radar antenna to the contact. Sometimes called azimuth a
Bearing Cursor: The radial line inscribed on a transparent disk which can be rotated manually about an axis coincide
Bistatic Radar: A bistatic radar system uses different antennas for transmission and reception.
Blind Range: Targets falling within the blind range range from the radar system are not detected.
Blind Sector: A sector on the radarscope in which radar echoes cannot be received because of an obstruction near t
Brilliance Control: Adjusts the intensity or brightness of the screen.
Cathode-Ray Tube (CRT): The radarscope (picture tube) within which a stream of electrons is directed against a fluorescent s
Chaff: Chaff refers to large quantities of passive reflecting material deployed in the atmosphere to counte
Clear-Air Echos: Radar returns from cloud- and precipitation-free (optical clear) air. Clear-air echos are caused by
Clutter: Unwanted radar echoes ret1ected from heavy rain, snow, waves, etc., which may obscure relatively lar
Contact: Any echo detected on the radarscope not evaluated as clutter or as a false echo.
Continuous Wave Radar (CW Radar): Continuous wave (cw) radar continually transmits energy in the direction of the target and receives
Contrast: The difference in intensity of illumination of the radarscope between radar images and the backgroun
Cross-Band Racon: A racon which transmits at a frequency not within the marine radar frequency band. To be able to use
Crystal: A crystalline substance which allows electric current t to pass in only one direction.
Definition: The clarity and fidelity of the detail of radar images on the radarscope. A combination of good reso
Depolarisation Ratio (LDR): Ratio between the reflectivity received at vertical polarisation, but transmitted with horizontal po
Differential Reflectivity (ZDR): Ratio between the reflectivity of a horizontal polarised pulse and the reflectivity of a vertical po
Diffraction: The bending of a wave as it passes an obstruction. Because of diffraction, there is some illuminatio
Digital Radio Frequency Memory (DRFM): Digital radio frequency memory is an approach being adopted by modern electronic attack (ea) systems
Directional Antenna: An antenna that transmits or receives signals only in a narrow angle. Decatur offers police radar w/
Doppler Blind Speed: Doppler blind speed is a major weakness of moving target indicator (mti) radar. Each time the dopple
Doppler Radar: A radar that detects and interprets the doppler effect in terms of the radial velocity of a target.
Doppler Velocity (V): Reflectivity-weighted average velocity of targets in the pulse volume. Determined by phase measureme
Double Stabilization: The stabilization of a heading upward ppi display to north. The cathode-ray tube with the ppi displa
Duct: A layer within the atmosphere where refraction and reflection results in the trapping of radar waves
Echo: The radar signal reflected back to the antenna by an object: the image of the reflected signal on th
Echo Box: A cavity, resonant at the transmitted frequency, which produces an artificial radar target signal fo
Echo Box Performance Monitor: An accessory which is used for tuning the radar receiver and checking overall performance by visual
Electronic Attack (EA): Electronic attack (ea), previously known as electronic counter measures (ecm), is conducted on radar
Electronic Bearing Line (EBL): An EBL control is used to display the relative or true bearing of a target on the display. The ebl i
Electronic Protection (EP): Electronic protection (ep) aims to ensure continued friendly use of the electromagnetic spectrum des
Electronic Support (ES): Electronic support aims to gain sufficient information about radar sensors to allow an understanding
Electronic Warfare (EW): Electronic warfare (ew) describes techniques that exploit an adversary's use of the electromagnetic
Elevation: The minimum angular separation in a vertical plan between two contacts at the same range and bearing
Face: The viewing surface (ppi) of a cathode-ray tube. The inner surface of the face is coated with a fluo
Fast Speed Tracking: Track both the strongest and the next faster vehicle at the same time, both in the moving and statio
Fast Time Constant (FTC): With ftc in operation, only the leading edge of an echo of a long-time duration is displayed on the
Fast Time Constant (FTC) Circuit: An electronic circuit designed to reduce the undesirable effects of clutter. With the ftc circuit in
Fluorescence: Emission of light or other radiant energy as a result of and only during absorption of radiation fro
Frequency Agility: Frequency agility refers to the radar's ability to rapidly change its operating frequency in a pseud
Frequency Diversity: Frequency diversity refers to the use of complementary radar transmissions or multiple radar systems
Frequency Modulated Continuous Wave Radar (FM CW Radar): Frequency modulated continuous wave radar makes use of frequency modulation to allow the range of a
Gain (RCVR) Control: A control used to increase or decrease the sensitivity of the receiver (rcvr). This control, analogo
Gain Control: Is used to adjust the sensitivity of the receiver and thereby regulating the intensity of the return
Ghost Effect: Sometimes when a radar signal hits a valid target, clutter may originate from multipath echoes creat
Ground Penetrating Radar (GPR): Ground penetrating radar uses radar principles to image, locate and quantitatively identify changes
Ground Radar: Ground radar is used to observe targets either on the surface of the earth, or airborne targets.
Guard Zone: An adjustable zone around the vessel set by the guard control. Once a guard zone is set, any target
Half-Power Point: The region of the radar beam where the signal strength drops to 1/2 of that strength measured at the
Heading Flash: An illuminated radial line on the ppi for indicating own ship's heading on the bearing dial. Also ca
Horizontal Beam Width: The beam width of the radar pulse measured in the horizontal plane. The size of which determines the
Identification Friend Or Foe (IFF): The identification friend or foe (iff) system is an example of a secondary radar system that is in w
In-Band Racon: A racon which transmits in the marine radar frequency band, e.g., the 3-centimeter band. The transmi
Intensity Control: A control for regulating the intensity of background illumination on the radarscope. Also called bri
Interference: Unwanted and confusing signals or patterns produced on the radarscope by another radar or transmitte
Interrogator: A radar transmitter which sends out a pulse that triggers a transponder. An interrogator is usually
Inverse Synthetic Aperture Radar (ISAR): Inverse sar (isar) is a variation on the sar theme that uses the motion of the target relative to th
Jammer: A jammer aims to degrade the operation of a radio receiver by transmitting a jamming signal that is
K-Band: Police traffic radar has been assigned specific frequencies by federal communication commission (fcc
Kilohertz (Khz): A frequency of one thousand cycles per second. See megahertz.
LASER: Laser is light, so this is not a microwave radar band. The laser radar guns operate in the infrared
Laser Radar (LIDAR): Laser radar (lidar) is a radar that uses light in place of the radio-frequency signals used in conve
Lobe: Of the three-dimensional radiation pattern transmitted by a directional antenna, one of the portions
Marine Radar: Marine radar is used for prevention of collisions between ships and as an aid to navigation when a s
Maximum Detectable Range: The maximum range at which a target can be detected is determined by transmitted power, scanner heig
Maximum Unambiguous Range: The pulse-repetition frequency (prf) of a radar system determines the maximum operating range of the
Megacycle Per Second (Mc): A frequency of one million cycles per second. The equivalent term MEGAHERTZ (MHz) is now coming into
Megahertz: A frequency of one million cycles per second. See kilohertz.
Microsecond: One millionth of one second.
Microwaves: Commonly, very short radio waves having wave lengths of 1 millimeter to 30 centimeters. While the li
Minimum Detectable Range: The minimum range at which an object can be detected due to antenna height, vertical beam width and
Monostatic Radar: A monostatic radar system transmits and receives its energy through the same antenna system or throu
Moving Radar: Is radar that clocks vehicles while the patrol vehicle is moving. Typically, the targets are those a
Off Center PPI: Offsets the sweep from the center of the screen to a location on the edge of the ppi to permit bette
Offset EBL: An electronic bearing line that can be moved to any position on the screen.
Pacing: Means the patrol car matches the suspected violator's speed. This is done with a calibrated speedome
Paint: The bright area on the ppi resulting from the brightening of the sweep by the echoes. Also, the act
Persistence: A measure of the time of decay of the luminescence of the face of the cathode-ray tube after excitat
Phased Array Radar: A phased array radar uses an antenna that consists of an array of antenna elements along with signal
Phosphorescence: Emission of light without sensible heat, particularly as a result of but continuing after absorption
Plan Position Indicator (PPI): The face or screen of a cathode-ray tube on which radar images appear in correct relation to each ot
Polarization: The orientation in space of the electrical axis of a radar wave. This electrical axis which is at ri
Primary Radar: Primary radar systems receive reflections of their own transmitted signals as returned signals from
Pulse: An extremely short burse of radar wave transmission followed by a relatively long period of no trans
Pulse Compression Radar: Pulse-compression radars make use of specific signal processing techniques to provide most of the ad
Pulse Doppler Radar: Pulse doppler radars make use of the dopper shift in pulse radar to determine the relative velocity
Pulse Length: The time duration, measured in micro seconds, of a single radar pulse. Also called pulse duration.
Pulse Length Error: A range distortion of a radar return caused by the duration of the pulse. The error is always on the
Pulse Radar: A pulse radar transmits a sequence of short pulses of rf energy, and estimates range to the target b
Pulse Radar: A pulse radar transmits a sequence of short pulses of rf energy, and estimates range to the target b
Pulse Repetition Frequency (PRF): The number of radar pulses transmitted each second. The pulse transmission rate is automatically len
Pulse Repetition Rate (PRR): The number of pulses transmitted per second.
Pulse Volume: The volume in which the radar data for one range bin are measured. Defined by the width of the radar
Racon: Radar beacon which, when triggered by a ship's radar signal, transmits a reply which provides the ra
Radar: Radar is used to describe systems that use electromagnetic energy to detect distant objects and poss
Radar Absorbent Material (RAM): Radar absorbent material has electrical properties similar to free space. When radar impacts radar a
Radar Altimeter: A radar altimeter is used by an aircraft to determine its height above terrain.
Radar Antenna: A radar antenna is a physical object used to focus, direct and concentrate electromagnetic energy in
Radar Beacons: Transmitters operating in the marine radar frequency band, which produce distinctive indications on
Radar Clutter: The term clutter refers to any objects that cause unwanted reflections of a radar's electromagnetic
Radar Cross Section (RCS): The radar cross section (rcs) of a target is the projected area that would intercept the transmitted
Radar Detector: An electronic device used to find any radar operating in the vicinity.
Radar Displays: A means of displaying target information in a clear and concise manner.
Radar Electronics: Traditional radar systems have relied on dedicated, radar electronics for their processing.
Radar Gun: Radar gun is a colloquial term for a type of police radar used to measure speed.
Radar Indicator: A unit of a radar set which provides a visual indication of radar echoes received, using a cathode-r
Radar Jammer: A radar jammer is a type of jammer designed specifically designed to jam radar receivers.
Radar Range: A measurement of the distance an object can be seen by radar based on the height of the antenna, the
Radar Range Equation (RRE): The radar range equation (rre) relates the range performance of a radar system to other radar compon
Radar Receiver: A unit of a radar set which demodulates received radar echoes, amplifies the echoes, and delivers t
Radar Receivers: Clutter is a major practical problem in the use of radar systems. Radar receivers often incorporate
Radar Reflector: A metal device designed for reflecting strong echoes of impinging radar signals towards their source
Radar Repeater: A unit which duplicates the ppi display at a location remote from the main radar indicator installat
Radar Screen: Radar screen is another term for radar display.
Radar Station: Radar station is a term used to describe a facility housing a ground radar.
Radar System: A radar system includes: a radar antenna, a radar transmitter, a radar receiver, radar signal proces
Radar Transmitter: A unit of a radar set in which the radio-frequency power is generated and the pulse is modulated. Th
Radar Warning Receiver (RWR): A radar warning receiver is a type of radar detector.
Radar Zone Of Influence: The area outside the main power beam or outside the beam width.
Radio Wave: Any electromagnetic wave at a frequency between approximately 10 kilohertz and 300,000 megahertz (a
Ramark: A radar beacon which continuously transmits a signal appearing as a radial line on the ppi, indicati
Range: The minimum range difference between separate contacts at the same bearing which will allow both to
Range Bin: Discrete element along a single radial of radar data at which the received signals are sampled. Rang
Range Control: Selects the scale used by the display and sets the distance between the range rings to correspond wi
Range Gate Pulloff: Targets being tracked using range gates can attempt to employ a tactic known as range-gate pull off
Range Height Indicator (RHI): A range height indicator (rhi) is a radar display that represents the height of the target on the ve
Range Markers: Equally spaced concentric rings of light on the ppi which permit the radar observer to determine the
Range Resolution: Range resolution is the ability of the radar to differentiate or resolve two targets that are close
Range Rings Control: Range rings are displayed on the screen when selected by this control and provide a rough estimate o
Range Selector: A control for selecting the range setting for the radar indicator.
Reflection: The return of all or part of a sound beam when it encounters the boundary between two media. The mos
Reflection Plotter: An attachment fitted to a ppi which provides a plotting surface permitting radar plotting without pa
Reflectivity Factor (Z): Integral over the backscatter cross-section of the particles in a pulse volume. For particles small
Refraction: The bending of the radar beam in passing obliquely through regions of the atmosphere of different de
Relative Motion Display: A type of radarscope display in which the position of own ship is normally fixed at the center of th
Resolution: The degree of ability of a radar set to indicate separately the echoes of two contacts in range, bea
Resolution In Bearing: The ability to display multiple objects individually that are closely spaced at the same range. Shor
Resolution In Range: The ability to display multiple objects individually that are closely spaced at the same bearing. Sm
Responder Beacon: Transponder beacon.
RHI (Range Height Indicator): Display on which radar signals are shown with height as the vertical axis and range as the horizonta
Same Direction Tracking: Tracking vehicles from behind or in front of the patrol vehicle going the same direction while the p
Same Lane Radar: Uses dual antenna moving radar to clock vehicles ahead or behind a rolling cruiser. Example: decatur
Sample Volume: The volume in which the radar data for one range bin are measured. Defined by the width of the radar
Satellite Radar: Satellite radar systems can be used for a variety of surveillance applications.
Scan: To investigate an area or space by varying the direction of the radar antenna and thus the radar bea
Scanner: A unit of a radar set consisting of the antenna and drive assembly for rotating the antenna.
Screen: The face of a cathode-ray tube on which radar images are displayed.
Sea Return: Clutter on the radarscope which is the result of the radar signal being reflected from the sea, espe
Secondary Radar: A secondary radar system is a cooperative target identification system in which the interrogator tra
Selectable Direction Tracking: This mode of radar operation allows the operator to monitor targets that are only going toward the p
Selectivity: A radar detector 's ability to differentiate between non-police radar signals and the real thing.
Sensitivity Time Control (STC): An electronic circuit designed to automatically increase the gain as the electron beam is deflected
Shadow Sector: A sector on the radarscope in which the appearance of radar echoes is improbable because of an obstr
Side Lobes: Unwanted lobes of a radiation pattern, ie., lobes other than major lobes. Also called minor lobes.
Sidelobe Blanking (SLB): Antennas with poor sidelobe performance can be improved by using sidelobe blanking techniques.
Sidelobe Cancellation (SLC): Sidelobe cancellation determines the direction of the jamming signal and effectively steers a null i
Sidelobe Control: Sidelobe control comes initially from good antenna design where one requirement is the minimisation
Spectral Width (W): A measure of the dispersion of velocities within the pulse volume. Standard deviation of the velocit
Speed Of Light: 186282.4 miles/sec or 299,792,458 meters/sec.
Spot Jamming: Spot jamming aims to concentrate the maximum amount of jammer power into the bandwidth of an individ
Stabilized Display (North-Upward): A ppi display in which the orientation of the relative motion presentation is fixed to an unchanging
Stationary Radar: Is operated from a stationary position. Virtually all radars work in this mode and some will also wo
Strobe: Variable range marker.
Surveillance Radar: Surveillance radar is used to detect targets within range of the radar.
Sweep: Determined by the time base or range calibration, the radial movement of the stream of electrons imp
Sweep Jamming: Sweep jamming aims to counter a number of different radar systems spread in frequency over a wide ba
Synthetic Aperture Radar (SAR): Synthetic aperture radar (sar) describes a way of synthesising a very large array antenna over a fin
Trace: The luminous line resulting from the movement of the points of impingement of the electron stream on
Tracking Radar: Tracking radar aims to accurately track the target in range, velocity or most commonly bearing.
Transponder: A transmitter-receiver capable of accepting the challenge (radar signal) of an interrogator and auto
Transponder Beacon: A beacon having a transponder. Also called responder beacon.
Trigger: A sharp voltage pulse usually of from 0.1 to 0.4 micro-seconds duration, which is applied to the mod
True Motion Display: A type of radarscope display in which own ship and other moving contacts move on the ppi in accordan
Unstabilized Display (Heading-Upward): A ppi display in which the orientation of the relative motion presentation is set to ship's heading
Variable Range Marker: A luminous range circle or ring on the ppi, the radius of which is continuously adjust able. The ran
Vertical Beam Width: The beam width of the radar pulse measured in the vertical plane. Most radar units have a vertical b
VG2: A vg2 gun is a special device used by law enforcement to identify the presence of a radar detector.
Visual Average Speed Computer And Recorder (VASCAR): This is little more than a glorified stopwatch, whereby the vehicle is timed over a set distance (fo
VRM: Variable range marker. An adjustable range ring used to measure the distance to a target. When the v
Wave: Transmission of energy through medium. Waves travel in repeating cycles of identical wavelength.
Wave Frequency: The number of cycle of waves that passes a point in one second. Frequency is measure in hertz (hz).
Wave Velocity: The speed at which the wave travels. All radio waves and light waves travel at a constant speed, the
Wavelength: A distance from one point in the wave cycle to the next equivalent point in the same direction as th
Weather Radar: Weather radar is used as an aid to weather forecasting.
X Band Radar: Radar frequency tolerance 10.525 ghz25 mhz frequency range 10.500-10.550 ghz. X-band radars have bee
Zoom Control: Zooms the display in on the area around the cursor or between the cursor and the display center to e