F

F-POLE - The distance between a missile-firing platform and its target at the instant the missile reaches the target. [10:27] Contrast with A-POLE.

FADE CHART - A plot of the field strengths at various ranges and altitudes. Also called a VERTICAL COVERAGE DIAGRAM. [] See also FADE ZONE .

FADE ZONE - An area in space where the reflected energy of a radar effectively cancels the direct-path energy of the radar. The degree of cancellation is affected by many variables, including antenna height, radar frequency, polarization of the signal, reflection coefficient of the earth at the point of reflection, angle of incidence at the point of reflection, etc. See also FADING. [] NOTE: This phenomenon has been exploited both by pilots in attempts to approach a radar site undetected as long as possible, and by radar operators who employed a "fade chart" consisting of a plot of the theoretical lobes and fade zones to estimate the altitude of approaching aircraft by noting the ranges at which the radar echo faded and reappeared.

FADING - The reduction in intensity or propagated power due to changes in parameters of the transmission media. [10:14] See also FADE ZONE.

FAIL-OPERATIONAL SYSTEM - A system designed for continued safe operation in the event of a malfunction. []

FAIL-SAFE - A designed property of an item which prevents its failures being critical failures. [3]

FAILURE - A FAULT TOLERANCE term.  A failure occurs when the delivered service of a system deviates from conditions stated in the service specifications.  [10:2701]  See also SYSTEM ERROR, FAULT, FAULT LATENCY.

FALSE ALARM - An erroneous target detection decision caused by noise or other interfering signal exceeding the detection threshold. [Patterned after false alarm (radar) in 3]

FALSE DOPPLER TARGET (FDT) JAMMING -- The use of a coherent repeater that produces a signal at a number of frequencies, spaced around the frequency of the target echo.  []  Also called MULTIPLE FREQUENCY REPEATER (MFR) JAMMING.

FALSE ECHO RETURN - [ACOUSTIC JAMMING term] The use of off-board decoys to generate false echo returns in order to defend against torpedo attack. [10:41]

FALSE-TARGET BMD COUNTERMEASURES - Actions taken to overwhelm ballistic missile defenses with large numbers of false targets and decoys, such as balloons.  The false targets and decoys could be designed to resemble the actual warhead, or be painted different colors so that uneven heating by the sun would generate a number of different INFRARED signatures to confuse defensive sensors and seekers.   [10:2609]  See also  EVASIVE MANEUVERS BMD COUNTERMEASURES,   SHROUDING BMD COUNTERMEASURES,  SUBMUNITION BMD COUNTERMEASURES,  TRAJECTORY BMD COUNTERMEASURES. 

FALSE TRACK CONTENT -- The number of tracks that do not correlate to real objects that are contained in the radar's local track file.  []

FAR INFRARED - The portion of the infrared spectrum band between 6.00 and 15.00 microns. [10:27] Synonymous with LONG WAVE INFRARED. See also ELECTRO-OPTIC, NEAR INFRARED, MID INFRARED, EXTREME INFRARED. NOTE: Far infrared sensors can detect "warm" airframes (contrasted with the sky).  [10:2547]

FAST FEATURE-RECOGNIZING OPTOELECTRONIC SYSTEM - A NEURAL NETWORK-based system which recognizes features and classifies images by processing the outputs of photo-sensors. [10:102]

FAST FOURIER TRANSFORM (FFT) - Efficient algorithms which solve Fourier Transforms of large bandwidth signals in near real time. [] See also WAVELET.

FAST INFRARED SNIPER TRACKER (FIRST) - An INFRARED LASER based system for detecting and tracking bullets in three dimensions at up to a range of 1000 meters.  It includes a computer-generated sniper location feature with an accuracy of less than three meters.  [10:2732]

FAST SEQUENTIAL JAMMING -- The ELECTRONIC JAMMING of predifined spot frequencies in an arbitrary sequence or in a continuous , band-like sequence called SWEEP JAMMING.  [10:2869]

FAST-TIME CONSTANT (FTC) CIRCUIT - A circuit with short time- constant used to emphasize signals of short duration to produce discrimination against extended clutter, long-pulse jamming, or noise. [3]

FAST TRANSISTOR - A superfast (switching rate of 74 billion times per second at room temperature), ultra-small (channel length of 80 nanometers) silicon-on-insulator transistor that operates at 1.5 volts. [10:2434]

FAST WALKER - A military space mission to detect orbiting spacecraft by sensing sunlight reflected from their solar arrays and external surfaces. [10:2509]  See also JOGGER, SLOW WALKER.

FATSAT - A low-cost satellite payload characterized by minimal expensive miniaturization, making it heavier and larger. [10:72] See also LIGHTSAT.

FAULT - A FAULT TOLERANCE term.  The judged or hypothesized phenomenological causE of an ERROR.  [10:2701]  See also FAILURE, FAULT LATENCY.

FAULT LATENCY - A FAULT TOLERANCE term.  The elapsed time between the occurrence of the FAULT and the first ERROR.  [10:2701]

FAULT TOLERANCE - The built-in capability of a system to provide continued correct execution in the presence of a limited number of hardware or software FAULTS. [3]    Fault tolerant techniques include...[10:2651]

FEDERATED ARCHITECTURE - A hierarchical system architecture involving a master computer and asynchronously operated slave computers and satellite microprocessors to control the sub-elements of the system. [10:9]

FEED-THRU (FEED-THROUGH) - See VIA.

FERRET - An aircraft, ship, or vehicle especially equipped for the detection, location, recording, and analyzing of electromagnetic radiation. [1]

FERRET RECEIVER - A receiver used to receive specific systems with great detail, or used to explore new sections of the electromagnetic spectrum previously unused for military purposes in order to discover emerging enemy capabilities. [10:2] See also ELECTRONIC WARFARE SUPPORT MEASURES.

FERROELECTRIC RANDOM ACCESS MEMORY (FRAM) - A non-volatile random access memory (RAM), FRAM uses a ferroelectric storage capacitor having hysteresis states corresponding to logic states where there are no half-selects for "read" and "write" addressing.  The FRAM is a modification of the dynamic random access memory (DRAM).   It takes less power that a DRAM, has comparable density, can be made radiation-hardened, and can be turned off without loss of data.  [10:2515]

FIBER OPTIC GUIDED MISSILE (FOG-M) -- A guided missile connected to its controlling source with as much as 60 kilometers of fiber optic cable with which the weapon transmits target images to the operator, and the operator is able to transmit commands to the weapon.  [10:2891]  NOTE:  Fiber optic guided missiles are said to be accurate to within 10 centimeters, and are relatively impervious to jamming and interference because signals are carried by light waves, rather that radio frequencies.

FIBER OPTICS - The branch of optical technology concerned with the transmission of radiant power through fibers made of transparent materials such as glass, fused silica, or plastic. [3]   For additional discussion, click .  [11.2]

FIELD EFFECT DETECTOR - A handheld device used to find human beings hiding behind barriers such as concrete walls and dense foliage, even at hundreds of feet distant.  The unit employs a passive detection system not vulnerable to types of countermeasures that might spoof INFRARED or THERMAL IMAGERs.  The device detects the electrostatic field given off by a human being and, like a divining rod, pulls the device in the user's hand and points toward the strongest field rather that providing an audio or video indication.  [10:2587]

FIELD EMISSION DISPLAY (FED) - A display that depends, not on THERMIONIC EMISSION from a CATHODE, as in CATHODE RAY TUBEs (CRTs), but on an array of millions of microscopic field emitters which propel electrons directly to the screen.   [10:2624a]  NOTE: As no beam deflection is needed, the distance between the cathodes and the screen need be only a millimeter or so.

FIELD OF REGARD -- The angular area within which the sensor can detect targets for a specified search rate.

FIELD OF VIEW (FOV) - The maximum solid angle visible by an electro-optic system. []

FIFTH GENERATION LANGUAGE (5GL) - A computer language that incorporates the concepts of EXPERT SYSTEMs, inference engines, and natural language processing. [3] See also FIRST GENERATION LANGUAGE, SECOND GENERATION LANGUAGE, THIRD GENERATION LANGUAGE, FOURTH GENERATION LANGUAGE.

FILM-FORMING POLYMERS - A cohesive surfactant mixed with an evaporation reducer, one use of which is to produce a detectable area on the surface of a body of water.  [10:2544]   See OCEAN MARKING.

FILTER - In electronics, a device which transmits only part of the incident energy and may thereby change the spectral distribution of energy: a. High pass filters transmit energy above a certain frequency; b. Low pass filters transmit energy below a certain frequency; c. Band pass filters transmit energy of a certain BANDWIDTH; d. Band stop filters transmit energy outside a specified frequency band. [1]

FINGER - A simple Internet protocol used to retrieve information about a web site.  Finger can be used to retrieve information about a user on a specific host (the provider). Typical results from the use of finger are: last login time, whether the user is currently logged on and, if so, which terminal, etc.  []  See also PACKET INTERNET GROPER (PING).  NOTE: Finger works only if the specified host supports it. Results can differ from host to host, inasmuch as a user can change the information.

FINGER-MOUNTED LASER - A finger-mounted LASER spotlight consisting of a nine-volt battery, a power supply, a laser diode, a focusing element and connecting cables. The device can project up to a 10-foot-wide laser beam as far as 300 feet. The beam is invisible to the naked eye and can be seen only with NIGHT-VISION equipment. []

FINGERPRINT - The human fingerprint is comprised of various types of ridge patterns, traditionally classified according to the decades-old Henry system: left loop, right loop, arch, whorl, and tented arch. Loops make up nearly 2/3 of all fingerprints, whorls are nearly 1/3, and perhaps 5-10% are arches. These classifications are relevant in many large-scale forensic applications, but are rarely used in biometric authentication. The fingerprint shown in Figure 1 below is a right loop.  

FINGERPRINT CHARACTERISTICS

Source: [11.4]

Referring to Figure 1, the discontinuities that interrupt the otherwise smooth flow of ridges, are the basis for most finger-scan authentication. Codified in the late 1800's as Galton features, minutiae are at their most rudimentary ridge endings, the points at which a ridge stops, and bifurcations, the point at which one ridge divides into two. Many types of minutiae exist, including dots (very small ridges), islands (ridges slightly longer than dots, occupying a middle space between two temporarily divergent ridges), ponds or lakes (empty spaces between two temporarily divergent ridges), spurs (a notch protruding from a ridge), bridges (small ridges joining two longer adjacent ridges), and crossovers (two ridges which cross each other).

FINGERPRINT IDENTIFICATION UNIT (FIU) - A device which can independently enroll, compare, and verify the fingerprint of a finger placed at its sensor.  The FIU contains a biometric sensor that can reject phony fingers, duplicate fingerprint images, or other ersatz digits.   The system can be used for security applications, such as access control to files and machinery.  [10:2610]

FIN-LINE ANTENNA -- An antenna consisting of a printed circuit inserted into an open-ended waveguide.  The printed circuit contains a fin line that extends a quarter wavelength beyond the waveguide aperture and feeds a pair of dipole-like elements.  The dipole antenna thus maintains a wide and nearly constant beamwidth, low voltage standing wave ratio (VSWR), and a circular symmetric radiation pattern for use in electronic warfare direction finding and surveillance applications.  [10:2646]

FIRE-AND-FORGET (F&F) - A weapon capability due to its having an on-board active terminal seeker that can guide the weapon to a target. Also called LAUNCH-AND-LEAVE. [] NOTE: A fire-and-forget weapon does not need monitoring nor course guidance by the launching platform, thus allowing the launching platform to maneuver or depart the area after weapon launch.

FIREWALL - A security product designed to prevent access by hackers, crackers, or other unauthorized entities.  It is a collection of components placed between two NETWORKS.  All traffic from inside to outside, or outside to inside, must pass through this security mechanism.  Only authorized traffic as defined by a security policy, is allowed to pass.  [10:2582]  A firewall guards and isolates an inside (private) network -- an intranet -- from an outside (hence untrusted) network -- the INTERNET, for instance.  A firewall may also guard some parts of an internal network from other parts.  [10:2619] NOTE: A firewall can be set up to allow only two-way communications, blocking only dangerous commands.  It also can be customized to allow only outward-bound communications, with no inward-bound access.   Another option is to set up the firewall to allow only incoming communications with no outgoing access.  Functions also can be customized within these general configurations.

FIREWIRE - An extremely fast electronic serial bus, described by IEEE Standard 1394, with rates about 400 Mb/s.  Firewire can carry independent streams of digital video and digital audio.  [10:2596]

FIRM KILL - Infliction of EFFECTIVE DAMAGE, short of physical destruction, on an inbound missile through the employment of electronic counter- measures techniques. [] Contrast with HARD KILL, SOFT KILL. See also FRONT-DOOR SYSTEM PENETRATION, BACK-DOOR SYSTEM PENETRATION, DIRECTED ENERGY WEAPON. NOTE: An example of a FIRM KILL is the destruction of a missile's guidance electronics.

FIRST GENERATION LANGUAGE (1GL) - A language that can be recognized by the processing unit of a computer. Such a language usually consists of patterns of 1s and 0s, with no symbolic naming of operations or addresses. [3*] Synonymous with MACHINE LANGUAGE.

FIRST GENERATION RADAR SIGNAL - A generic classification of radar signal sophistication. First generation radar signals have rudimentary features such as simple pulsed radio frequency, constant pulse repetition interval, mechanical beam scanning, frequencies in the A to I bands of the ELECTROMAGNETIC SPECTRUM, and numerous MINOR LOBES in the radiation pattern. [10:34] See also SECOND GENERATION RADAR SIGNAL, THIRD GENERATION RADAR SIGNAL, and FOURTH GENERATION RADAR SIGNAL.

FIXED VERY LOW FREQUENCY (FVLF) - A submarine broadcast system which is (2001) the primary command and control link to the submarine force.  It allows submarines to remain submerged and still receive operational communications.  [SPAWAR]   See also EXTREMELY LOW FREQUENCY (ELF).  NOTE:  The high power FVLF transmitter systems operate at 14.0 to 30.0 kHz, providing long range ocean area coverage.

FLAMELESS EXPULSION GRENADE - A NONLETHAL WEAPON consisting of a rubber ball grenade body that contains pulverized chemical agents (CN or CS).  No pyrotechnics are involved - a CO₂ cartridge at the center of the grenade disperses the irritant through ports at the sides of the grenades.  [10:2745]

FLAMING DATUM - A DATUM whose location is the target damaged by a submarine attack. []

FLAMING RECEIVER - An expendable combination infrared and RF decoy. []

FLARE - In countermeasures, a PYROTECHNIC device launched from ships and aircraft to serve as a target and lure infrared homing and optical devices away from their true targets. [8]    NOTE: Pyrotechnic flares may be characterized by the following parameters:

FLARE REJECTION - The ability of a missile to recognize and disregard PYROTECHNIC countermeasures. []

FLASH BLINDNESS - Impairment of vision resulting from an intense flash of light. It includes temporary or permanent loss of visual functions and may be associated with retinal burns. See also DAZZLE. [1]

FLASH MEMORY - High-density non-volatile computer memory designed for rugged applications. The advantages of flash memory are non-volatility and a simple and inexpensive cell structure.  The major disadvantages are that individual bytes cannot be erased and overwritten, but instead, sections of the device or the entire device are erased.  Also, erase/write cycles are much slower than read operations and may require complex erase and write algorithms to insure the device is not damaged during these operations. [10:2525]

FLEX-CUFFS - Lightweight disposable restraints (hand-cuffs) to immobilize individuals.  They can be carried in large quantities by soldiers.  []

FLEX TARGETING - The ability (e.g., of bombers) to change targets while en route.  []

FLOATPLANE - A seaplane (i.e., an airplane designed to take off and touch down on water) whose fuselage is supported by struts attached to two or more pontoon floats.  []  Contrast with the flying boat, a seaplane with its fuselage formed into a boat hull (with possibly wing-support pontoons), having the buoyancy and strength necessary to take off, touch down, and float on water.

FLOPTICAL DISK - A very high density floppy disk which uses an optical servo system to position the magnetic read-write head with great accuracy.  [10:2538]

FLUENCE - A measure of microwave energy strength. Specifically, a time-integrated power density. [10:16]

FLUIDICS - A control technology that uses a fluid medium - liquid or gas - to perform sensing, amplification, logic, and control functions based on the medium's internal fluid dynamics. [10:103]  NOTE: Fluidic controls employ streams of fluid to deflect other streams and make sensing, controlling and computing devices operable under conditions where others may fail.  Fluidic controls have been found to be extremely reliable, easy to maintain and highly resistant to radiation and dust.  [10:2746]

FLUORESCENT NANOCLUSTER - A binary storage technique that provides 3-dimensional storage, creating a dense storge medium that can be written to or read in parallel.  [10:2891]  NOTE:  A compact disk currently holding 650 megabytes of data could, using fluorescent nanocluster techniques, hold 650 megabytes squared of data.

FLY-ALONG FLARE - An infrared countermeasures (IRCM) flare which, after launch, will fly along at a distance from the launching aircraft to act as a decoy against the IR seeker of an incoming missile equipped with a FORWARD-BIAS COUNTERMEASURES.  [10:2818]  Also called KINEMATIC FLARE.

FLY-BY-LIGHT (FBL)  -- An aircraft control technology designed to replace electronic data transmission, mechanical control linkages, and electronic sensors with optical components and subsystems.   Fly-by-light systems are inherently lightweight and impervious to electromagnetic radiation.  [10:2673]   See also POWER-BY-WIRE.

FLY-BY-WIRE (FBW) CONTROL - Electronic control of aircraft control surfaces using redundant channels having dissimilar computer algorithms and communications, so that each channel operates independently of the others. [10:50] NOTE: FBW control replaces the mechanical cable/quadrant/pushrod system on aircraft.

FLYING PEANUT - A remotely-controlled unmanned vertical take-off and landing reconnaissance vehicle capable of real-time transmission of infrared imagery. [10:73]

FLYING RADAR TARGET (FLYRT) - A chaff-launcher ejected flying decoy that emulates the radar cross-section and motion of a ship. [JED "Washington Report 5/93]

FLY ON THE WALL - A MICRO AIR VEHICLE (MAV) with bulging hex-covered "eyes" which can fly to and place itself on a target and emit a low energy code, allowing a homing weapon to guide in on its position.   [10:2751]  Also called ROBO-BUG.  See also MICROMECHANICAL FLYING INSECT (MFI).   NOTE:  The fly would be operated via remote control by on-site special operations personnel to the designated mean point of impact (DMPI).

FOCAL PLANE - In an optical system, a plane through the focal point perpendicular to the principal axis of the system, such as a lens or mirror. [10:14]

FOCAL PLANE ARRAY (FPA)- See STARING DETECTOR.

FOE-AS-FRIEND IDENTIFICATIONS -- The percentage of friendly tracks in the system that correlate with hostile real objects.  []  Contrast with FRIEND-AS-FOE IDENTIFICATIONS.

FORCE STRUCTURE - The component of MILITARY CAPABILITY that relates to numbers, size, and composition of the units that comprise the force; e.g., divisions, ships, air wings. [1]

FOREIGN INSTRUMENTATION AND SIGNALS INTELLIGENCE (FISINT) - Technical information and intelligence information derived from the intercept of foreign instrumentation signals by other than intended recipients. Foreign instrumentation and signals intelligence is a category of SIGNALS INTELLIGENCE (SIGINT). [1] See also TELEMETRY INTELLIGENCE. NOTE: Foreign instrumentation signals include but are not limited to signals from telemetry, beaconry, electronic interrogators, tracking/fusing/arming/firing command systems, and video data links.

FORWARD-BIAS COUNTERMEASURES - An infrared counter-countermeasures (IRCCM) technique used by an infrared-homing missile against a decoy infrared countermeasures (IRCM) flare in which the IR missile seeker is turned off momemtarily allowing the IRCM flare to fall away from the seeker's field of view (FOV).  [10:2818]   Also called PUSH-AHEAD COUNTERMEASURES.  See also FLY-ALONG FLARE.

FORWARD ERROR CORRECTION (FEC) - A coding technique designed to clean up signals damaged by channel CROSSTALK, noise, and other interference common to space communication links.  FEC codes detect and correct data errors at the receiver (forward) end of the transmission.  [10:2568]

FORWARD LOOKING INFRARED (FLIR) - INFRARED sensors used aboard fixed wing aircraft and helicopters for intelligence gathering and to provide real-time sensors for pilots to improve their ability to fly at night and in inclement weather conditions. [10:6]

FORWARD PASS - Transferring control of a fired weapon to another platform. This is a facet of COOPERATIVE ENGAGEMENT. [10:128]

FORWARD SCATTERING - SCATTERING of an electromagnetic wave into directions that are at acute angles to the direction of propagation of the incident wave. [3]

FORWARD TELLING - Transferring information to a higher level of command. [1] See also BACK TELLING, CROSS TELLING, OVERLAP TELLING, RELATERAL TELLING, TRACK TELLING.

FOTOFIGHTER - A highly maneuverable plane (conceptual) equipped with an array of diode lasers that would allow the plane to engage multiple targets simultaneously.  At low powers, the arrays can function as transmitters and receivers for LPI communications.  [10:2749]

FOURTH GENERATION LANGUAGE (4GL) - Fourth generation productivity tool. A programming tool characterized by a reduction of numbers of instructions required by THIRD GENERATION LANGUAGEs by a factor of 10 (or provides an equivalent improvement in productivity if its interface with the programmer is not a language per se). Additions in the 4GL include direct manipulation of databases, and screen-manipulation ability, including windowing. [10:93] See also FIRST GENERATION LANGUAGE, SECOND GENERATION LANGUAGE, FIFTH GENERATION LANGUAGE.

FOURTH GENERATION PROGRAMMING - See FOURTH GENERATION LANGUAGE.

FOURTH GENERATION RADAR SIGNAL - A generic classification of radar signal sophistication. Fourth generation radar signals have sophisticated features reflecting the most modern technology available. [10:34] See also FIRST, SECOND, and THIRD GENERATION RADAR SIGNAL.

FRACTAL - Formally, A curve whose Hausdorff-Besicovitch dimension is larger than its Euclidean dimension. Fractals are a natural way of representing many of the shapes in nature. One application of fractals is in simulation systems. [10:120] NOTE: A fractal is any image or object that can be constructed using an iterative mathematical formula. A fractal is characterized as a curve having a fractional, versus integral, dimension. Fractals are sometimes referred to as "visual representations of chaos". Examples of fractal curves are the Phoenix Curve, Mandelbrot Set, Julia Set, Hilbert Curves, Von Koch Snowflake, and Gosper Curve.

FRACTAL ANTENNA - An antenna comprised of elements patterned after self-similar designs (i.e., any arbitrarily small region of a fractal looks like the entire fractal).  It is capable of many resonances, depending upon the iterations.  [10:2601]  See also GENETIC ANTENNA.

FRACTIONAL BANDWIDTH (FBW) - The ratio of the instantaneous bandwidth to the carrier bandwidth.  [10:2571] NOTE: For example, an S-band radar operating at 3 GHz with a bandwidth of 300 MHz would have a fractional bandwidth of 0.3/3 = 0.1.

FRAGILITY - The inherent inability of a force or organization to respond to changes in external conditions.  [10:2760]  NOTE:   Fragility may be affected by overt actions of the adversary or by natural occurrences which sap energy and resources.

FRAGMENTARY ORDER (FRAGO) - An abbreviated form of an OPERATION ORDER (OPORD), usually issued on a day-to-day basis, that eliminates the need for restating information contained in a basic operation order.  It may be issued in sections.   [10:2764]

FRAME FREQUENCY - The inverse of FRAME TIME.  []

FRAME TIME - The time required by a SCANNING sensor (active or passive) to execute one complete search scan.  []  See also SCANNING DETECTOR.

FRANGIBLE PROJECTILE - A NONLETHAL WEAPON projectile which disintegrates (e.g., turns to iron dust) upon striking a hard object.  The usual purpose is to limit collateral damage, such as behind a door or wall struck by the projectile.  []

FREE-ELECTRON LASER (FEL) - A directed energy weapon which employs accelerator technologies known as induction accelerators and radio frequency accelerators. [5:1] See also BEAM-PLASMA DEVICE; VIRTUAL-CATHODE OSCILLATOR ; CHEMICAL LASER; EXCIMER LASER; HIGH ENERGY LASER, X-RAY LASER. NOTE: Free-electron lasers work by first depositing large amounts of energy in gases and then extracting some fraction of that energy in a collimated beam.

FREQUENCY - The number of periods per unit time. Specifically, the number of identical cycles per second. [3] See also HERTZ.

FREQUENCY AGILE RADAR - A pulse radar in which the transmitter carrier frequency is changed between pulses or groups of pulses by an amount comparable to or greater than the pulse bandwidth. [3]  NOTE: The frequency agile radar is considered to be a LOW PROBABILITY-OF-INTERCEPT (LPI) RADAR.

FREQUENCY AGILITY - The ability of an electronic transmitting system to quickly change operating frequencies, generally on a pulse-to-pulse basis while the frequency remains stable during the pulse. These frequencies are automatically selected and successive transmissions may be random or determined according to some programmed algorithm. [] See also SNIFFING.

FREQUENCY DECONFLICTION - A systematic management procedure to coordinate the use of the electromagnetic spectrum for operations, communications, and intelligence functions. Frequency deconfliction is one element of electromagnetic spectrum management. [7:CJCS MOP 6, APPENDIX B]

FREQUENCY DOMAIN REFLECTOMETRY (FDR) - A REFLECTOMETRY technique using sine waves.  FDR directly measures the phase difference between the incident and reflected waves; any faults in the line will generate resonances between the two signals, which are detected by the frequency domain reflectometer.    [10:2871]  See also SMART WIRE, STANDING WAVE REFLECTOMETRY (SWR) and TIME-DOMAIN REFLECTOMETRY (TDR).

FREQUENCY HOPPING (FH) - A SPREAD SPECTRUM technique in which the transmitted frequency is pseudorandomly changed at a rate called the "hopping rate". [4:13] Contrast with DIRECT SEQUENCE SPREADING, TIME HOPPING. NOTE: In Frequency Hopping, the total available bandwidth is the spread bandwidth; however, the instantaneous bandwidth is less than the spread bandwidth. This technique is used in communications, radar, jamming, and other applications.

FREQUENCY MODULATION (FM) - A form of ANGLE MODULATION in which the instantaneous frequency of a sine-wave CARRIER is caused to depart from the carrier frequency by an amount proportional to the instantaneous value of the modulating wave.  See also AMPLITUDE MODULATION (AM), PHASE MODULATION (PM).

FREQUENCY REUSE - The simultaneous use of a frequency for two or more purposes. []

FREQUENCY SEARCH-AND-LOOK JAMMING - The employment of NARROWBAND JAMMING that is tuned automatically over a broad frequency band and automatically locked onto a particular frequency.   [] 

FREQUENCY SELECTIVE SURFACE (FSS) -- An adjustable plastic screen used in RADOMEs or ADVANCED ENCLOSED MASTs (AEMs) that allows certain frequencies to pass while blocking others.  []

FREQUENCY SHIFT KEYING (FSK) - A form of FREQUENCY MODULATION (FM) in which the modulating signal shifts the output frequency between predetermined values, and the output WAVE has no discontinuities.   [3]  LISTEN to a Frequency Shift Keying (FSK) signal.

FREQUENCY SPECIFIC JAMMING - [ACOUSTIC JAMMING term] Acoustic jamming of a defined acoustic sensor. [10:41]

FREQUENCY SPECTRUM - See ELECTROMAGNETIC SPECTRUM

FREQUENCY SYNTHESIZER - A device which translates the stable frequency of a precision frequency standard, such as a crystal-controlled oscillator, into a number of frequencies over a spectrum range.   There are two types of frequency synthesis: DIRECT SYNTHESIS (DS) and INDIRECT SYNTHESIS (IS).  [10:2616]

FRIEND-AS-FOE IDENTIFICATIONS -- The percentage of hostile tracks in the system that correlate with friendly real objects.  []  Contrast with FOE-AS-FRIEND IDENTIFICATIONS.

FRONT-DOOR COUPLING - See FRONT-DOOR SYSTEM PENETRATION.

FRONT-DOOR SYSTEM PENETRATION - A DIRECTED ENERGY WEAPON term for energy entering a target system through its antenna. [10:16] Synonymous with FRONT-DOOR COUPLING. Contrast with BACK-DOOR SYSTEM PENETRATION. NOTE: Front-door system penetration is most effective at the target system's antenna design frequency.

FRONTLIGHT - A lamp that reflects off the front surface of a reflective display.  It is used when ambient light is insufficient or, in the case of a reflective field-sequential color display, to sequentially illuminate the display with red, green, and blue light.  [10:2600]   Contrast with BACKLIGHT.

FUEL AIR EXPLOSIVE (FAE) - A THERMOBARIC WEAPON that dispenses an aerosol fuel cloud which ignites as it descends (assuming that it is a submunition launched from a CLUSTER BOMB UNIT (CBU)).  The overpressure from the explosion flattens objects underneath the cloud.  [10:2908]  NOTE:  FAEs may also be delivered by other means, such as a planted aerosol dispenser with a delayed fuze, etc.)

FULL AUTHORITY DIGITAL ENGINE CONTROL (FADEC) - The regulation of engine power and efficiency by integrating, in REAL TIME, the flight control computer with the variables (sensed parameters, specified schedules, control logic, ...) coupled with mission requirements.  [12]

FULL SPECTRUM INFORMATION OPERATIONS - A U.S. Army integrating strategy merging the following disciplines: [10:2710]

FUNCTIONALLY SIGNIFICANT ITEM (FSI) - A shipboard item which performs a function and is significant to the performance of the system of which it is a part. A functionally significant item can be a system, subsystem, equipment, component, or any combination of these. [NAVSEAINST 4790.1A]

FUZE JAMMING - A generic term relating to fuze countermeasures that will pre-detonate missile fuzes. [4:1]

FUZE SERRODYNE MODULATION - A fuze jamming technique employed to produce the Doppler shift that will trigger a Doppler fuze. [4:1]

FUZZY LOGIC - An approach to computing based on "degrees of truth" rather than the usual "true or false" (1 or 0) Boolean logic on which the modern computer is based.  Fuzzy logic includes 0 and 1 as extreme cases of truth, but also includes various states of truth in between.  [10:2768]

October 13, 2001 05:36 PM -0400