HACKER - A person who delights in having an intimate understanding of the internal workings of a system - computers and computer networks in particular. The term is almost universally misused in a pejorative context, where CRACKER would be the correct term. [10:2736] Also called WHITE HAT HACKER. See also GRAY-HAT HACKER.
HAND-EMPLACED JAMMER - A lightweight, man-portable, expendable solid-state jammer with self-disabling features, designed to be hand-emplaced to operate against threat signals. [4:26] See also LEAVE-IT-BEHIND JAMMER.
HANDOFF - The passing of tracking responsibility from one system to another, such as from a search radar to a fire-control radar. []
HANDSHAKING - Part of a communications PROTOCOL that requires the interchange of predetermined signals between devices prior to making a connection. [10:45]
HARD KILL - The physical destruction of a weapon or a platform through employment of electronic counter- measures techniques, bombs, or missiles. [] Contrast with SOFT KILL, FIRM KILL.
HARD-KILL ECM - HARD KILL weapons which employ electronic warfare concepts to achieve target destruction. [] See also DIRECTED ENERGY WEAPON, FRONT-DOOR SYSTEM PENETRATION, BACK-DOOR SYSTEM PENETRATION; LETHAL ELECTRONICS COUNTERMEASURES.
HAVE STARE (HS) - An X-band (8-12 GHz) 200 kw tracking RADAR that can detect small space debris in the 1 to 10 cm range, depending on altitude. []
HAYSTACK LONG RANGE IMAGING RADAR (LRIR) - Part of the Millstone Haystack complex consisting of two radars that share hardware and power which precludes simultaneous operations. The two radars are the Haystack Long Range Imaging Radar (LRIR) and the Haystack Auxiliary Radar (HAX). These radars support missions for the U.S. Space Command, the National Science Foundation, and NASA. Their primary function is for deep space imaging of foreign and domestic satellites and orbital debris. The radars image every new foreign space launch in Near Earth (NE), and image domestic satellites in trouble. The LRIR takes two-dimensional images of earth satellites by processing highly stable, coherent signals to extract target return range and doppler information. The radar is capable of tracking and imaging near-earth (NE) satellites, 200-4,000 km altitude, as well as deep space objects out to 40,000 km range and beyond. The maximum tracking rate of the Haystack antenna is 2 degrees/second, and this sets the limits on observation of near-earth satellites, especially those passing nearly overhead. The limitation on deep space objects is their size: a one square meter radar cross section at 40,000 km is roughly the detection threshold of the radar. The radar operates at 10-GHz center frequency and transmits over a broad range of pulse widths and pulse repetition frequencies, including a 1-GHz linear FM pulse which, when compressed, is used for radar imaging. The radars also provide detection of objects in space and gather information about their estimated size, velocity, altitude, and direction of travel. [10:2804]
HAZARDS OF ELECTROMAGNETIC RADIATION TO PERSONNEL, ORDNANCE, AND VOLATILE MATERIALS (HERO) - See ELECTROMAGNETIC RADIATION HAZARDS.
HEAD-UP DISPLAY (HUD) - A display of flight, navigation, attack, or other information superimposed upon the pilot's forward field of view. [1] See also HORIZONTAL SITUATION DISPLAY, VERTICAL SITUATION DISPLAY.
HEALING AGENT - See AUTONOMIC HEALING
HEDGEHOG (HH) - An anti-submarine mortar-like projectile used by destroyers and anti-submarine ships circa 1942 - 1960. They were favored over depth charges because they could be fired in patterns 100-150 yards ahead of the ship while it still maintained sonar contact with the target submarine. Each hedgehog was approximately 7 inches in diameter at the warhead end and carried 30 lbs of TNT (or 34 lbs of Torpex). Twenty-four hedgehogs were mounted in open view in a cradle-like base on the bow of the ship. The cradle was mounted on a power drive which allowed a training arc of 20 degrees on either bow (later versions allowed a full gun train). The ring-finned tail of each hedgehog was sleeved to a rod mount called a spigot which held the firing pin. The spigots also had a tilt capability to compensate for the roll-and-pitch motion of the deck . Hedgehogs were fired in pairs at intervals which deployed the 24 weapons in a 1 - 1.5 second interval, forming a circular pattern at water entry. [ALL HANDS magazine, April 1958, p45] See also MOUSETRAP. NOTE: Hedgehogs had the additional advantage over depth charges (which detonated at preset depths) in that they did not detonate except on contact. This if the submarine was not hit, sonar conditions were not deteriorated by bubbles and water disturbance generated by a detonation, as with depth charges. Click to view photos and additional information about hedgehog installations.
HELICOPTER MINE - A device which will autonomously search, detect, track, identify, engage and destroy enemy helicopters flying at speeds up to 350 kilometers per hour and at altitudes up to 250 meters. It possesses a positive hostile target signature identification processor that sorts and identifies helicopter acoustic signatures. The mines can be equipped with countermobility remote control system transceivers, enabling them to be de-activated for friendly force passage and mine recovery. [10:2546]
HERTZ - The unit of FREQUENCY, one cycle per second. [3]
HETERODYNE LADAR - See HOMODYNE LADAR.
HIDDEN SCAN - An ECCM technique for use by semi-active missile guidance receivers. [8] See also INVERSE GAIN ECCM.
HIGH ENERGY DENSITY MATERIAL (HEDM) - Material composed of high- energy ingredients, such as explosives, propellants, and pyrotechnics. [10:89]
HIGH ENERGY LASER (HEL) - A HARD-KILL ECM device which employs lasers used as directed energy weapons. They work by accelerating electrons to very high velocities, then causing them to radiate some of their kinetic energy at the proper wavelength and in the proper direction in resonance with light waves in the electron beam. [5:1] EXAMPLES: X-RAY, CHEMICAL, FREE-ELECTRON, and EXCIMER LASERs.
HIGH ENERGY MILLIMETER WAVE (MMW) - Directed energy in the MILLIMETER WAVE region of the ELECTROMAGNETIC SPECTRUM. []
HIGH-ENERGY LASER WEAPON SYSTEM (HELWEPS) - A defensive system incorporating a HIGH ENERGY LASER (HEL) designed to protect Aegis-class cruiser and destroyers against high-speed, sea-skimming cruise missiles. The self-contained, modular (fire-control, ammunition, and pump) weapon configuration is intended to replace a ship's forward 5-inch/54 gun mount. The device is a deuterium-fluoride (DF) LASER which produces a coherent beam that can (with only about 1-second engagement duration) destroy missile targets radomes at 4 kilometers, and optical systems at up to 10 kilometers. [10:2560] See also MIRACL.
HIGH ENERGY RADIO FREQUENCY (HERF) - A weapon that can direct high levels of RF radiation at digital devices such as computers and navigation equipment, thereby disrupting their operation. [] Also called EMP/T BOMB.
HIGH-FREQUENCY SURFACE WAVE ARRAY RADAR (HIFAR) - A BISTATIC RADAR operating in the HF (3 - 30 MHz) range, used for ocean surveillance. At these frequencies, the radar waves propagate over the ocean surface for long distances, well beyond the normal radar horizon. []
HIGH OFF-BORESIGHT SYSTEM (HOBS) - A helmet-mounted sight and short-range missile system to combat Mig-29s. []
HIGH POWER COMBINER - A radio frequency (RF) device which combines the outputs of multiple solid state amplifiers over a given frequency range. []
HIGH-POWERED MICROWAVES - See HIGH-POWERED RF.
HIGH-POWERED RF - A term replacing HIGH-POWERED MICROWAVES, high-power energy roughly above 1,000 MHz. []
HIGH-POWER SOURCE NOISE JAMMING - A type of BARRAGE JAMMING in which noise is added to the high-power signal of the jammer. [10:36] Contrast with LOW-POWER SOURCE NOISE JAMMING.
HIGH POWERED ACOUSTIC WEAPON - A NONLETHAL WEAPON versatile high power acoustics system with a tunable, less-than-lethal incapacitating capability. [10:2745] See also ACOUSTIC WEAPON.
HIGH SPEED ANTI-RADIATION MISSILE (HARM) - High-speed anti-radiation missiles designed for use against early-warning radars and air defense systems. [] See also ANTI-RADIATION MISSILE.
HIGH-SPEED CHOP - A technique to achieve compatibility between RADAR WARNING RECEIVERs (RWRs) and ECM systems. The receiver and transmitter operate effectively simultaneously by implementing a high-speed time sharing scheme. [10:2400] See also LOOK AROUND, LOOK OVER, and LOOKTHROUGH.
HIGH TEMPERATURE SUPERCONDUCTIVITY (HTSC) - Superconductivity at temperatures above 125 degrees Kelvin (-234 degrees Fahrenheit). [10:116]
HOG NOSE - See RIVET JOINT
HOG CHEEKS - See RIVET JOINT
HOLE-FINDING - An ECCM technique used against a noise jammer which partially covers a radar frequency band. It consists of scanning the receiver bandwidth at the end of a pulse repetition period to determine the frequency having the lowest jamming level at which the radar will operate during the next pulse repetition period. [8] Synonymous with HOLE-HUNTING and HOLE-SEEKING.
HOLE-HUNTING - See HOLE- FINDING.
HOLE-SEEKING - See HOLE- FINDING.
HOLOGRAM - An in-depth apparent three-dimensional image with great realism produced by illuminating an object field with two interrelated coherent light beams, one directly from a light source and the other slightly delayed, thus giving the three-dimensional appearance. [10:14]
HOLOGRAPHIC DATA STORAGE SYSTEM (HDSS) - Optical interference images recorded in a light-sensitive, usually erasable, medium. To achieve high storage density, the images are multiplexed -- that is, more than one image occupies the same volume within the crystal. To differentiate among images, subtle recording differences, such as changing the reference angle, changing the wavelength of the laser light, or other optical stratagems, are used. Later, the inverse optical conditions are used to reconstruct the hologram so that data can be optically or photographically read out. [10:2594]
HOLOGRAPHIC MEMORY - A four- dimensional (the fourth dimension is wavelength) storage medium based on a method called "spectral hole burning" to retain holographic images (HOLOGRAMs), which can later be retrieved using low level laser rays. [10:2410]
HOME-ON-JAM (HOJ) - A means whereby a missile guidance receiver utilizes the self-screening target jamming signal to develop angular steering information so that the missile can home on that target. [8]
HOMING GUIDANCE - A system by which a missile steers itself towards a target by means of a self-contained mechanism which is activated by some distinguishing characteristics of the target. [1] See also ACTIVE HOMING GUIDANCE, PASSIVE HOMING GUIDANCE, SEMI-ACTIVE HOMING GUIDANCE.
HOMODYNE LADAR - A laser radar which includes an optical detector constantly receiving a local oscillator (LO) signal in the form of a low-power laser beam. When a reflected return from a target is received, the returned beam is combined with the LO beam on the optical detector which picks up the difference frequency between the two beams. The frequency of the beat signal indicates target relative speed and direction. [] Synonymous with HETERODYNE LADAR.
HOP - (1) In FREQUENCY HOPPING (HF), the shifting of a transmitter from one frequency to another. [] (2) For network ROUTING, a segment of a path to a destination on a network (a path from the origin to a destination on a network is a series of hops through ROUTERS). [10:2736] See also ROUTE.
HORIZONTAL SITUATION DISPLAY - An electronically generated display on which navigation information and stored mission and procedural data can be presented. Radar information and television picture can also be displayed either as a map overlay or as a separate image. [1] See also HEAD-UP DISPLAY, HORIZONTAL SITUATION INDICATOR, VERTICAL SITUATION DISPLAY.
HORIZONTAL SITUATION INDICATOR (HSI) - An electronically generated display that provides a basic horizontal view of the aircraft's navigation picture. [] NOTE: In the F-15E, for example, HSI can provide navigation data to selected ground navigation facilities such as TACAN or Instrument Landing System (ILS), or to onboard navigation systems such as the Inertial Navigation System (INS).
HORN - An antenna consisting of a waveguide section in which the cross- sectional area increases toward an open end which is the aperture. [3]
HORN ANTENNA - A radiating element having the shape of a horn. [3]
HOST-BASED INTRUSION DETECTION - A type of INTRUSION DETECTION that examines computer operations data to detect HACKERS. [10:2853] Also called COMPUTER-BASED INTRUSION DETECTION. See also ANOMALY DETECTION, NETWORK-BASED INTRUSION DETECTION, PORT SCAN, SIGNATURE DETECTION.
HOSTILE ARTILLERY LOCATOR (HALO) - A system which will detect and locate all sources of high energy sound and provide rapid analysis and identification of artillery, guns, mortars and machine guns. It is accurate to 20 meters at range of 15 km; and can work at ranges of 30-40 km. [10:2732] NOTE: HALO processes signals from pre-positioned microphones to identify specific types of ordnance by the acoustic waves they make in flight. HALO can also identify and track engine sounds and even human footfalls. [10:2889]
HOT CHAFF - An infrared counter- measure employing small chaff elements which generate infrared radiation when exposed to air. When deployed, hot chaff generates a broad signature source which counters an infrared detector's decoy discrimination features. [] See also INFRARED COUNTERMEASURES.
HOVERING DECOY - See NULKA.
HUMAN FACTORS ECCM - A generic ECCM technique that covers the ability of an electronic warfare officer (EWO), a radar operator, a military vehicle operator, a commanding officer, and/or any other EW-associated personnel to recognize the various kinds of ECM, to decide what the appropriate ECCM should be, and/ or to take the necessary ECCM action within the framework of this command structure. [8]
HUMAN FACTORS ECM - A generic ECM technique that covers the ability of an EW-related individual or supervisor to recognize the need for ECM, to decide what the appropriate ECM should be, and to take the necessary ECM action within the framework of the individual's command structure. [Patterned after the definition of HUMAN FACTORS ECCM from reference 8]
HUMAN INTELLIGENCE (HUMINT) - A category of intelligence derived from information collected and provided by human sources. [1] See also HUMAN RESOURCES INTELLIGENCE.
HUMAN RESOURCES INTELLIGENCE - The intelligence information derived from the intelligence collection discipline that uses human beings as both sources and collectors, and where the human being is the primary collection instrument. Sometimes called HUMINT. [1] See also HUMAN INTELLIGENCE.
HUMANE WEAPON - See NONLETHAL WEAPON (NLW)
HUNTER SENSOR SUITE (HSS) - A vehicular integrated, long-range target acquisition suite mounted on an extendible mast assembly platform, remotely controlled from an operator's station located inside the vehicle, e.g., HMMWV. HSS operates both on the move and stationary. The integrated sensor suite includes 2nd-generation THERMAL IMAGING, ACOUSTIC DETECTORS, day TV, Eyesafe laser Rangefinding, Aided Target Recognition (ATR), high density integrated processing. color digital maps, image compression/transmission, GLOBAL POSITIONING SYSTEM (GPS), North-Seeking Module (NSM) and secure communications. [10:2801]
HYBRID CHANNELIZED/SUPERHETERODYNE RECEIVER ARCHITECTURE - A receiver system that uses multiple-channel channelizers to provide frequency video and to act as a pulse-by-pulse tuner for the associated narrowband superheterodyne receiver. A portion of each received signal is fed into the channelizer, with the remaining signal going straight into the superheterodyne after a delay of several hundred nanoseconds. Both receivers generate amplitude video, offering a higher probability of intercept with high levels of sensitivity and measurement accuracy. []
HYBRID SPACE MINE - A variation of the SPACE MINE. The hybrid space mine is maintained in a "storage orbit" and is maneuvered to its target by command signals. A hybrid space mine's storage orbit may be such that it is covertly placed among drifting space debris until the time it is maneuvered to its target. [5.8]
HYBRID THREAT - A threat resulting from a mix of systems having differing national origins, such as a Soviet aircraft using a French IFF system. []
HYDROGEN FLUORIDE (HF) LASER - A CHEMICAL LASER which combines heated hydrogen (produced in a combustion chamber similar to the one in a rocket engine) with fluoride gas to produce excited hydrogen fluoride molecules. The light beam that results radiates on multiple lines between 2.7 µm and 2.9 µm. These wavelengths transmit poorly through the atmosphere. Even so, the BALLISTIC MISSILE DEFENSE (BMD) organization is considering (1997) HF lasers for space-based defenses needing to propagate through only he upper atmosphere. [10:2607] See also DEUTERIUM FLUORIDE (DF) LASER.
HYDROMAGNETICS - The science that deals with an electrically conducting fluid, as a liquid metal or an ionized gas. [] Also called MAGNETOHYDRODYNAMICS. See also MEASUREMENT AND SIGNATURE INTELLIGENCE.
HYPERENCRYPTION - The hiding of a message within a very large stream of data. [10:2906] NOTE: In the face of hyperencryption, a code-breaker would be unable to store the message-within-data for eventual decoding because the total amount would simply be overwhelming.
HYPERLINK -- (1) A pointer from a segment of text or from an image to a BOOKMARK or UNIVERSAL RESOURCE LOCATOR (URL), which may be located on the same page, another page or computer file in the web site in which the hyperlink exists, or to a file or bookmark in another web site on the World Wide Web. Hyperlinks allow the user to navigate between bookmarks on the same page (example: click here to move to the bookmark "HYDRODYNAMICS" above), to other files on the same site (as most of the hyperlinks in this lexicon) or to bookmarks or files on other web sites (as in the hyperlinks to sound files under ELECTROMAGNETIC JAMMING). (2) A pointer within a HYPERTEXT document which points (links) to another document, which may or may not also be a hypertext document. See also HYPERTEXT MARKUP LANGUAGE (HTML). []
HYPERSPECTRAL IMAGERY -- A process in which visual light is significantly enhanced by a computer processor, enabling the smallest changes in color variance of the water to be detected, thus improving the ability to detect submarines. [10:2656] The HYPERSPECTRAL (IMAGING) SENSOR is designed to provide a detailed analysis of the entire light spectrum from visible light up to FAR INFRARED. Current (1999) multispectral imaging sensors can break this range into a dozen or more sections for individual analysis. The hyperspectral imaging sensor can examine extremely narrow bands of this range, allowing the sensor to look for specific chemical compositions that reflect light only in those very narrow bands. This provides a capability to "look" through dense foliage and detect, for example, camouflage paint. The image presented to the sensor's user would give a visual representation of that "hidden" source in the same manner as infrared or other displays. [10:2692] See also AIRBORNE TARGETING AND CROSS-CUEING SYSTEM (ATACCS), LITTORAL AIRBORNE SENSOR-HYPERSPECTRAL (LASH), HYPERSPECTRAL SENSOR.
HYPERSPECTRAL SENSOR - A reconnaissance sensor system used to quickly pinpoint objects that are undetectable to traditional ELECTRO-OPTIC (EO) equipment. The system divides the incoming optical radiation into hundreds of spectral bands and analyzes that information for specific signatures unique to a scene. The signatures are processed in a way that allows accurate detection of objects that are different from their backgrounds. [10:2590] Synonymous with HYPERSPECTRAL IMAGING SENSOR. See also PORTABLE HYPERSPECTRAL IMAGER FOR LOW LIGHT SPECTROSCOPY (PHILLS). NOTE: A HYPERSPECTRAL IMAGING SENSOR is a MULTISPECTRAL IMAGING SENSOR having more than 20 discrete spectral bands. [12]
HYPERTEXT - A document, written in HYPERTEXT MARKUP LANGUAGE (HTML), which contains HYPERLINKS to other documents, which may or may not also be hypertext documents. Hypertext documents are usually retrieved from the INTERNET, using the WORLD WIDE WEB (WWW). [10:2736]
HYPERTEXT MARKUP LANGUAGE (HTML) -- A programming language used to build Web sites. It contains standard codes, or tags, that determine how a Web page looks when a browser displays it. ( For a listing of current HTML tags, click ). HTML tags may be used to create headings, paragraphs, and lists. HTML tags also make possible the HYPERLINKs that connect information on the World Wide Web. [] See also DYNAMIC HYPERTEXT MARKUP LANGUAGE, GENERALIZED MARKUP LANGUAGE, JAVA NOTE: In most browsers, you can see the underlying HTML code for the displayed page by selecting the Menu item "View", and then "Source".
HYPERVELOCITY INTERCEPTOR - A KINETIC KILL VEHICLE that can reach speeds of more than 8,000 feet per second within fractions of a second after launch. [10:74]
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