Abstract: A method and apparatus for generating sharper and more accurate LADAR intensity images is disclosed. The LADAR system includes an optical transmitter and receiver that generates and scans a laser beam in a target field. A backscatter detector senses the magnitude of the generated laser beam. A signal processing unit uses the magnitude of the transmitted laser beam to adjust the magnitude of received reflections to produce a sharper intensity image.

Abstract: A modular signal processing architecture adapted for use with a focal plane array of detectors. The inventive architecture includes an analog signal processing module (42) for adjusting signals from the focal plane array (12). A nonuniformity correction module (44) provides signal adjustment parameters to the analog signal processing module (42) for each of the detectors in the array (12). A control module (80) provides control signals to each of the modules in the system as required for a desired system configuration. In a specific embodiment, the control signals are communicated via programmable registers on each module. Software running on the system control module provides the control signals to the programmable registers to reconfigure the system in response to the addition of modules thereto. Hence, additional modules may be easily incorporated into the system without a costly redesign of same.

Abstract: A detection system for use in an aircraft which is able to monitor atmospheric conditions ahead of the aircraft, generate an alarm signal if adverse atmospheric conditions exist ahead of the aircraft and generate information which indicates the position of the adverse conditions so the adverse conditions can be avoided. The system is able to detect the presence of volcanic ash cloud ahead of the aircraft and, if desired, can also be used to detect a high density of sulphur dioxide gas and/or clear air turbulence ahead of the aircraft. The system monitors infrared radiation received by the aircraft, generates intensity signals representative of at least one predetermined wavelength of the radiation and compares intensity signals with reference signals or intensity signals of another infrared wavelength.

Abstract: A sensor system comprises a plurality of sensor stations of the same type for surveillance of an area intended to include an object to be protected, the sensor stations being distributed essentially along the periphery of a circle, in the central part of which an object to be protected is intended to be contained. Each sensor station includes a detector unit which is arranged to scan an arc in an azimuth sector of the circle allocated to it up towards the background of the sky in each of two detection fields formed along the arc having different elevation angles with respect to the detector unit. The time of the passage of a target between the two detection fields is measured, and the target position is calculated relative to the sensor station on the basis of the measured time, the speed of the target, the angle between the detection fields and the angle to the target.

Abstract: A dual mode radar transparency allowing passage of both RF radiation and IR radiation comprises an aerogel base and ceramic skin overlaying the aerogel base. The aerogel base comprises a low density ceramic material. A method of fabricating a dual mode radar transparency allowing passage of both RF radiation and IR radiation comprises the steps of preparing a colloidal dispersion of a ceramic material in a medium, increasing a concentration of the colloidal dispersion by evaporation to create a suspension, and placing the suspension in a mold. The suspension is solidified to form an aerogel and the aerogel is joined to a ceramic skin.

Abstract: Preprocessor for the detection of point sources in an infrared (IR) "scenario" or field, essentially consisting of an input interface; a transversal filter; an adaptable threshold device, consisting in turn of a two-port internal memory and of an arithmetic processing unit; a resource assembly and an output interface. The system can be used in surveillance in the IR band, more particularly, in the field of detection of signal emission on ships, planes, helicopters, transportation means, armored cars, airports and anywhere it is necessary to detect artificial or natural heat sources from as far away as possible. In comparison with the prior art, the preprocessor differs from the point of view of the filtering system, adjusting the filter itself to the real form of the IR signal which is punctiform and depends on the electro-optic characteristics of the sensor.

Abstract: A focal plane imaging array (FPIA) (16) for use in a direct detection imaging device (10) for conducting radiometric imaging at microwave and millimeter-wave frequencies is disclosed as having an internal electronic calibration source (36). The plurality of energy detecting pixel elements (14) which comprise the FPIA (16) include a detection circuit (34) and a calibration circuit (36). The calibration circuit (36) is uni-directionally coupled to the detection circuit (34) to allow a known calibration signal "pulse" to be introduced into the detection circuit (34). The calibration pulse is processed by the pixel detection circuit and the output signal is compared with the pixel's responsivity value. Adjustments in the pixel gain and sensitivity may then be made as appropriate.

Abstract: The microwave section of a dual technology sensor comprising microwave and infrared sections may be periodically tested. This is done by arranging for the output of the microwave section to be monitored at times corresponding to microwave pulses and at times coresponding to no microwave pulses. If the microwave section is operating properly then a difference should be seen in the output between the "pulse" and "no pulse" times. Because this test can involve a change in the average energy output by the microwave section it can also affect the infrared section of the sensor which often inadvertently receives radiation from the microwave source. Thus the infrared section may be tested using this effect.

Abstract: A tri-sensor track association based on ranked candidate pairs and measures of their proximity is described. The track association employs a three dimensional assignment scheme, simple enough to be implemented in real-time, which preserves the most accurate pairwise links of the highest ranked pairs, requires at least two pairwise links for any tri-sensor global track association, and minimizes the time average statistical bearing displacement between associated tracks.

Abstract: An automatic target acquisition and tracking system has been developed for a focal plane array seeker. The automatic target acquisition is achieved by three independent target acquisition algorithms, viz., the maximum likelihood classification, the video spatial clustering, and the target-to-interference ratio. Each algorithm operates asynchronously and provides independent target detection results. Target information is then combined hierarchically in a probabilistic fashion and prioritized. The highest priority target is handed off to a dual mode tracker consisting of a minimum absolute difference correlation tracker and a centroid tracker. The dual mode tracker subsequently provides a feedback signal to a proportional navigation system or other guidance/control system for directing the flight path of a munition.

Abstract: A dual-mode, radio frequency, optical-wavelength detector apparatus includes RF-transparent optical elements adapted to focusing optical energy in a wavelength range including ultraviolet through infrared wavelengths, on an optical detector, and an RF antenna located behind the optical elements. One embodiment of the apparatus employs a Cassegrain infrared optical telescope system having a concave primary mirror, the front surface of which has applied thereto multiple layers of dielectric material comprising an interference filter reflective in a band of infrared wavelengths, and transmissive to radio frequency energy. A convex secondary mirror having a similar reflective coating is so located as to reflect infrared energy backwards through a central coaxial perforation through the primary mirror onto an infrared detector.

Abstract: A tri-sensor track association based on ranked candidate pairs and measures of their proximity is described. The track association employs a three dimensional assignment scheme, simple enough to be implemented in real-time, which preserves the most accurate pairwise links of the highest ranked pairs, requires at least two pairwise links for any tri-sensor global track association, and minimizes the time average statistical bearing displacement between associated tracks.

Abstract: A method of and a system for scanning a scene for the purpose of classifying a plurality of moving objects located in the scene and having an average distance between them, including the steps of performing a sweep of the scene, during the sweep, producing a multiplicity of detections of at least one portion of the scene at a rate such that a distance traveled by the moving objects between detections is small with respect to the average distance, and calculating, from the multiple detections, two-dimensional motion information for at least some of the moving objects.

Abstract: A method of processing IR signals from a repetitively scanned array of photovoltaic cells is shown to consist of the steps of: (a) subtracting IR signals received on successive scans to produce response signals corresponding only to IR signals from moving or scintillating objects; (b) generating inhibiting signals for IR signals from the edges of wind-driven clouds or from scintillating objects; and (c) inhibiting those response signals that are from the edges of moving clouds or scintillating objects.

Abstract: A multi-spectral seeker system for detecting radiation in the infrared (IR) band and a plurality of radio frequency (RF) bands suitable for use in a guided missile is disclosed. The IR and RF seekers are coaxially integrated on a single gimbaled platform and share a common aperture without significant performance degradation. In the preferred embodiment, the IR seeker uses a Cassegrainian reflector assembly with surfaces reflective to IR but transparent to RF signals. The first RF seeker uses a resonant dichroic reflector antenna which is transparent to RF signals at frequencies no closer than 0.5 octaves from the dichroic reflector system operating frequency. The second RF seeker may use any suitable RF antenna system although a planar-array of multi-mode spiral antennas or a standard flat plate slotted array are preferred. The second RF seeker may operate in an active, semi-active, or passive mode.

Abstract: A coaxial multiple-mode antenna system (10) is disclosed, including a coaxial input section (14) for coaxially collecting, for example, MMW and IR electromagnetic radiation. The IR radiation is focused to a point at the input section's focal plane, while the MMW beam has a relatively large width in this plane. An interface section (16) includes an IR section (18) and MMW section (20) that allow the two beams to be separately processed with a minimum of losses. In that regard, the MMW section includes a lens (42), having an incident surface, the center of which is positioned at the focal plane. An optical fiber (46) extends axially through the lens and has an incident end that is aligned with the incident surface of the lens. The lens quasi-optically transmits the MMW beam to a detection circuit (26), while the optical fiber transmits the IR beam to detection circuit (22). Because the optical fiber receives the IR beam before it is processed by the lens, IR losses are limited.

Abstract: A bistatic radar system includes a transmitting radar site; a receiving radar site; and an optical fiber RF link system for transmitting RF signals from the receiving site to the transmitting site and for transmitting command and control signals from the transmitting site to the receiving site.

Abstract: A combined infrared-radar detection system wherein a radar antenna also serves as the primary mirror in an infrared focusing arrangement.

Abstract: A spinning strip aperture imaging radiometer sensor system and data processing method that is capable of synthesizing full circular aperture images from a plurality of image frames acquired by the strip aperture imaging sensor. One embodiment of the imaging system comprises a rotating strip aperture wide field of view telescope, a two dimensional detector array used to detect images in the telescope's focal plane, a rotation compensation device used to prevent rotational smear during the integration time of the detectors, a signal processor used to record a plurality of image frames of a target scene that is imaged by the telescope as it rotates around its optical axis, and a signal processor and method used to synthesize the full circular aperture image from the recorded images. The operation of the full aperture image synthesis method hinges upon the ability of the rotating strip aperture to measure all of the spatial frequencies contained in a full circular aperture image measurement.

Abstract: Intrusion detection apparatus including a microwave transmitter comprising a generally unshielded dielectric resonating oscillator, whose parasitic field is radiated within a volume and Doppler detection apparatus for sensing received Doppler signals reflected by a moving object within the volume.

Abstract: A friendly target recognition system is provided for use in combat zones ing friendly and unfriendly target objects residing therein. Transmitting means are mounted on each friendly target object in the combat zone to transmit radiation in the form of coded, short burst data packets according to a particular digital transmission code sequence. A receiving means is mounted on the targeting device that is aimed at one targeted object. The receiving means has a field-of-view that is limited to the one targeted object such that the presence of the transmitted radiation according to the particular digital transmission code sequence is indicative of a friendly target object.

Abstract: Guidance apparatus for a tactical guided missile uses a dual-mode sensor having both active millimeter wavelength RF sensing capability and passive infrared sensing capability within a single aperture. A dual reflector-antenna assembly is formed by chemical vapor deposition of dielectric material transparent to infrared and RF radiation. Embedded within the reflector assembly is an RF microstrip antenna array, formed by thin-film metalization techniques, which defines an antenna beam axis. A surface of the reflector assembly is ground, optically polished, and coated with infrared reflective material to form a primary reflecting surface of a Cassegrainian optical system, which also includes a secondary mirror, for defining an infrared detection beam axis coincident with the antenna beam axis. Infrared radiation from a target is concentrated by the Cassegrainian optical system onto an infrared detector to produce a first guidance signal.

Abstract: An identification of friend from foe (IFF) device is described containing a radio transceiver (F) which, in addition to being designed for communication purposes, is equipped for transmitting, receiving, and evaluating IFF signals. The IFF device further includes a laser transmitter (LS) and an optical receiver (LE) which are coupled to the radio transceiver (F) via a controller (G). For identification, unmodulated direction-selective light signals and modulated nondirectional radio signals are used.

Abstract: The present application describes a method for the protection of aircrafts against flying objects comprising UV-homing heads, this method being characterized in that the aircrafts are, at least temporarily, provided with an UV-emitting radiation source.

Abstract: The invention relates to a surveillance sensor provided with at least one surveillance radar antenna 1 and at least one co-located and co-rotating electro-optical surveillance sensor 5 mechanically connected to said radar antenna. A combined panoramic picture is compiled by combining information from both sensors using a common track unit 30.

Abstract: Sensor detections received over time are analyzed to find relationships therebetween. For example, radar echoes, outputs from an infrared sensor, etc., may be analyzed to find target tracks. First, gross similarities are detected by mapping, e.g., angular readings into angle bins using each of a plurality of hypothesized rates of change of angle. Those sensor detections which are found to correlate with respect to angular measurement are subjected to similar mapping into range bins using rate of change of range. The angle and range bins are compared to determine which represent target tracks. The resulting target tracks may be used to revise the parameters and repeat the same process. For example, if one of the "target" tracks detected on the first pass has an angle of 30.degree., an angle rate of 2.degree. per minute, a range of 2 kilometers and a range rate of 3 kilometers/second, this target track might be evaluated to determine whether it is a cluster of targets using angle rates varying from 1.degree.

Abstract: An aircraft threat monitoring system has several sensors responsive to a potential threat external to the aircraft such as a radar warning receiver, a radar sensor, a missile approach warning receiver, a forward-looking infrared detector and an electro-optic sensor. Each sensor has a respective inference processor the outputs of which are supplied to a groundspace map manager and an airspace map manager. The map managers collate the processor outputs to derive a threat output signal which is supplied to a planner programmed with tactical route information. The map managers also control operation of the sensors such as by modifying their sensitivity, scan or frequency in accordance with the output from other sensors.

Abstract: A pulse radar for operation at 94 GHz and higher frequencies is shown to include an antenna, a diplexer and first detector that are each optically fed so that radio frequency signals may be, when transmitting, passed through the diplexer to the antenna and, when receiving, from the antenna through the diplexer to the first detector.

Abstract: A fiber optic radar guided missile system 10 is disclosed which includes a radar receiver 12 disposed in a missile for receiving radar reflections and providing a first optical signal in response thereto. An optical receiver 14 is disposed at a launcher for receiving the first optical signal and for providing a set of electrical signals in response thereto. A fiber optic link 32 is connected between the missile and the launcher for communicating the first optical signal from the radar receiver 12 to the optical receiver 14.In a specific embodiment, the invention 10 includes a first system 12 disposed in a missile for receiving radar reflections which includes only an antenna 16 for receiving radar reflections, a radar seeker 18 for providing a first electrical in response to the received radar reflections, and a first fiber optic transmitter 26 for converting the first electrical signal into a first optical signal.

Abstract: A method and apparatus for generating thermal waves in a sample and for measuring thermal inhomogeneities at subsurface levels using millimeter-wave radiometry. An intensity modulated heating source is oriented toward a narrow spot on the surface of a material sample and thermal radiation in a narrow volume of material around the spot is monitored using a millimeter-wave radiometer; the radiometer scans the sample point-by-point and a computer stores and displays in-phase and quadrature phase components of thermal radiations for each point on the scan. Alternatively, an intensity modulated heating source is oriented toward a relatively large surface area in a material sample and variations in thermal radiation within the full field of an antenna array are obtained using an aperture synthesis radiometer technique.

Abstract: A target simulates the coincident infrared and microwave signatures of a rce being tracked by a missile whose systems are undergoing test.

Abstract: A target detector (1) for detecting targets provided with transmitter means (3, 5) for simultaneous generation of different electromagnetic waves having different frequencies which are transmitted by means of an emission and detection device (2). The target detector is also provided with receiving means (3, 4, 5) for obtaining, by means of the emission and detection device (2), target signals comprising target information received at different frequencies. A signal processing unit (15, 16, 17) is provided for processing the target signals in combination to obtain target-representing signals.

Abstract: An autonomous radar transmitting system transmits radar signals which simulate the presence of a police-manned radar station. A controller runs pseudo-randomizing programs to select the width of a radar pulse transmitted as well as the time lapse between subsequent pulses. The radar output of the system is therefore sufficiently random to prevent a detecting circuit from identifying it in the time it takes for a motorist with a radar detector to reach the radar source. This system is battery powered and a photovoltaic panel is provided to recharge the battery, thus giving the system a long lifespan. Also provided is an infrared detector through which infrared signals may be input to the controller. Thus, external control is provided without making the system susceptible to tampering or vandelism. Most of the electrical components are enclosed in a weatherproof casing capable of being mounted in a number of discrete, convenient locations.

Abstract: A system which combines intensity area correlation is disclosed for use with terrain height radar and infrared emissivity systems to give a simultaneous three-mode map matching navigation system. The infrared system senses passive terrain emissions while the height finding radar measures the time between transmission of a radar signal to the ground and receipt of a radar return. The intensity correlator uses the radar returns to sense changes in the reflection coefficient of the terrain. Map matching all three modes simulanteously provides an accurate, highly jam resistant position determination for navigation update.

Abstract: An Aided Target Recognition System (ATR) is provided wherein the recognit abilities of two ATR sensor subsystems with mutually exclusive false alarm characteristics are fused by a decision circuit to provide an improved false alarm rate versus the probability of target detection. The sensors, which respond to different types of radiation, have different false alarm patterns for the same set of targets and a decision circuit which contains logical function elements to exploit the difference in these patterns.

Abstract: A multi-spectral imaging apparatus with a common collecting aperture, which combines a high performance infrared imaging system with a high performance millimeter wave transceiving system. Two mirror surfaces are combined with a refractive corrector in the infrared mode and with a single reflective parabolic antenna in the millimeter wave mode. The dual mode system functions well in a scanning as well as a staring configuration.

Abstract: The invention pertains mainly to a method and a device for the display of targets and/or target positions using the data acquisition means of a weapons system.The device of the present invention can be used to display the target or the direction of the target acquired by missile homing heads. This data comes as a complement, and other data on the position of the target is used to ascertain that the homing head is properly locked on as well as to supplement any lack of information caused, for example, by a breakdown in the display systems. The invention can be applied mainly to the building of anti-aircraft defense launching platform or anti-aircraft and anti-tank launching platform.

Abstract: A position sensing apparatus and method useful for surveying, marking, and grading implement sensing and control is disclosed. The position sensing apparatus includes two laser reference stations, each of which projects a laser beam that periodically sweeps in a plane across the area to be surveyed. Each time a laser beam strikes the opposite reference station, a radio timing signal is broadcast by that reference station. The position sensing apparatus also includes a portable sensing station that comprises a laser beam receiver, a radio reciever, and a programmed computer. The planar position of the portable sensing station relative to the reference stations is computed by a triangulation technique based on the relative timing of detection of the laser beams by the laser beam receiver and the reception of the radio timing signals by the radio receiver. Elevation is determined according to the height at which one of the laser beams strikes the laser beam receiver.

Abstract: The proposed surveillance system for surveilling a given scenario in azimuth and in elevation comprises an infrared surveillance detection device passively operating in the infrared region and a radar search and/or tracking device operating in the active mode for range determination. The targets or target information data are obtained as video signals from the infrared surveillance detection device during each search cycle and are processed in an infrared data processor. The video signals are discriminated and stored in an infrared signal processor with respect to their elevation angle values (.lambda.) and azimuth angle values (.alpha.). The values of the azimuth angle (.alpha.) are simultaneously fed to a radar activation and contol unit for triggering a momentary or short-time emission by the radar search and/or tracking device.

Abstract: This invention relates to providing aural indications to a person indicative of that person's environment and, more particularly, to providing such indications in three-dimensional form. More specifically, this invention relates to providing such three-dimensional aural indications to an individual to provide aural attitude information useful to that individual.

Abstract: A distance-measuring arrangement including transmission means for transmitting a wave in a measuring field, receiving means for receiving the wave reflected from a moving body moving in the measuring field and for producing a beat signal from the Doppler frequency. Delimiting means is provided for forming, in the measuring field, at least two datum lines (Ca and Cb) and processing means is provided for processing the distance information obtained from measuring the Doppler frequencies at the instants when the moving body crosses the datum lines. The delimiting means are formed from thermal detectors disposed in an optical assembly having at least two optical axes for defining the datum lines. A timing circuit is provided for defining the instants at which the moving body crosses the datum lines and for applying this information to the processing means.

Abstract: A dual mode target seeking system for airborne vehicles which operates under two different frequencies simultaneously includes a radio frequency antenna comprising a slotted plate defining a ground plane with an image plate positioned in front of the ground plane at a distance chosen such that multiple reflected rays are in phase with each other and with waves incident on the image plate. The slotted plate and image plate have aligned central openings through which an electro-optical system for operating under a chosen electro-optical frequency range, for example under infrared frequencies, projects. The electro-optical system includes a detector unit positioned behind the antenna and a focussing system for directing incoming electro-optical radiation into the detector unit. The focussing system includes first and second lenses mounted in the openings in the image plate and slotted plate, respectively.

Abstract: A dual mode antenna that allows both millimeter wave and infrared radiation o enter a single aperture and propagate through a common transmission device to a point where the respective energies are divided to follow separate paths for subsequent processing. An electromagnetic transmission guide or waveguide for the system comprises a tubular waveguide member, having a beam directing lens or lenses therein, for maintianing low-loss, gaussian beam propagation of millimeter wave energy therethrough. A waveguide fiber array is coupled into or adjacent to the tubular member at one end and retrieves the infrared radiation but allows the millimeter wave radiatin to pass. Cassegrainian optics are positioned adjacent the other end of the tubular member for directing incoming millimeter and infrared energy into the guide. Subsequently, the energy impinges on the beam directing lens means that separates the respective energies, dividing them into two separate and distinct paths.