Abstract: Methods and apparatus for early detection and identification of a threat such as individuals carrying hidden explosive materials, land mines on roads, etc. are disclosed. Methods comprise transmitting radar signals in the direction of a potential threat, measuring the energy in reflected signals, dynamically generating a threat threshold value from signals received from multiple areas and comparing the energy in the reflected signals corresponding to different areas to the generated threat threshold value. The threat threshold value may be generated by averaging the weighted reflected energy measured from different areas during a single scan of a region including the different areas. The contribution to the threshold from different areas is weighted in some embodiments as a function of the distance from the transmitter and/or receiver to the particular area. Analysis of areas and treating different areas as segments facilitates accurate analysis and display of threat information.

Abstract: A path in three-dimensions for an object in flight is determined according to a radar signal reflected by the object. The radar signal is transmitted at an offset angle from horizontal sufficient to capture the object within the transmitted radar signal. The transmitted radar signal is reflected by the object to form a reflected radar signal containing an indication of a position of the object. The reflected radar signal is received and used to determine two-dimensional position information for the object by detection of the indication of the position of the object in the received radar signal. Position information is derived in three-dimensions from the position information in two-dimensions. The path information representative of the path for the object is obtained from the position information in three-dimensions based on an optimization of a curvature of said path information.

Abstract: Emitter target range and heading are estimated from bearing measurements enhancing bearings-only estimator convergence to a target track, and permitting optimization of an observer position relative to the target at the end of the total bearing measurement period. One or more estimates of the target range, speed and heading made from bearing measurements before an observer maneuver are used to determine the most appropriate observer maneuver giving complete bearings-only target-motion-analysis observability. A set of parameters characterizing a set of potential emitter signal sources is generated based on measured emitter characteristics. A most probable set of emitter platforms is identified and the emitter operating mode and corresponding platform set are associated with a kinematic regime set. A specific speed or discrete set of speeds best adapted to a set of all possible platform missions, emitter speed as a continuous function of emitter range, and emitter range are all determined.

Abstract: Emitter target range and heading are estimated from bearing measurements enhancing bearings-only estimator convergence to a target track, and permitting optimization of an observer position relative to the target at the end of the total bearing measurement period. One or more estimates of the target range, speed and heading made from bearing measurements before an observer maneuver are used to determine the most appropriate observer maneuver giving complete bearings-only target-motion-analysis observability. A set of parameters characterizing a set of potential emitter signal sources is generated based on measured emitter characteristics. A most probable set of emitter platforms is identified and the emitter operating mode and corresponding platform set are associated with a kinematic regime set. A specific speed or discrete set of speeds best adapted to a set of all possible platform missions, emitter speed as a continuous function of emitter range, and emitter range are all determined.

Abstract: Methods and apparatus for early detection and identification of a threat such as individuals carrying hidden explosive materials, land mines on roads, etc. are disclosed. Methods comprise transmitting radar signals in the direction of a potential threat, measuring the energy in reflected signals, dynamically generating a threat threshold value from signals received from multiple areas and comparing the energy in the reflected signals corresponding to different areas to the generated threat threshold value. The threat threshold value may be generated by averaging the weighted reflected energy measured from different areas during a single scan of a region including the different areas. The contribution to the threshold from different areas is weighted in some embodiments as a function of the distance from the transmitter and/or receiver to the particular area. Analysis of areas and treating different areas as segments facilitates accurate analysis and display of threat information.

Abstract: A combined defense and navigational system on a naval vessel is disclosed. The disclosed system includes a track-while-scan pulse radar which is controlled to provide either navigational information or tracking information on selected targets. Additionally, the disclosed system includes a plurality of guided missiles, each of which may be vertically launched and directed toward intercept of a selected target either by commands from the track-while-scan radar or from an active guidance system in each such missile.

Abstract: The present invention relates to a system for using signals scattered by targets to determine position and velocity for each of the targets and comprises a set of transmitters and receivers of electromagnetic or acoustic signals, said transmitters and receivers dispersed to known points. Each pair of transmitter and receiver, mono-static or bi-static, is named a measuring facility. The ranges of the transmitters are chosen so that a target at an arbitrary point within the position space can be measured via scattering in the target by at least four, but preferably many more, measuring facilities.

Abstract: A commercial airliner (10) carries a sensor that detects a characteristic (21) associated with a man portable missile (20). Raw sensor data is transmitted via a wireless data-link (41) to ground stations (31-33) that process the airliner transmission and determine both the presence of the missile and a precise aircraft position. Countermeasures are fired to detonate within a close proximity of airliner in order to divert the detected missile.

Abstract: In regard to radar guidance of a launch container (15) for fragmentation projectiles (16) for defending against an attacking missile (12), from the object (11) to be protected, the present invention affords a radar guidance system which can be inexpensively set up from existing components and which, in the absence of interfaces between the object (11) and the launch container (15), operates in a trouble-free manner if, for space monitoring and target acquisition, provided on the substructure (14) of the launch container (15) which is fixed with respect to the object, there is a planar antenna (20) which transmits its target information to a target-tracking radar (19) which is integrated into the launch container (15), for directly guiding the launch container (15) on to the approach of the missile (12) to be defended against.

Abstract: A method of tracking a target (2) moving in an airspace and a target tracking system (10) for performing the method are described. A search sensor (12) searches a search space at a first clock rate (2&pgr;/&Dgr;T1) and establishes target information in regard to a track (4) flown through by the target (2). Calculation means (16) extrapolate an expected flight path (6) from the target information established and provide flight path data, which describes the expected flight path (8), to a tracking sensor (14), which covers a tracking space (15), and provides this data at a second clock rate (2&agr;/&Dgr;T2), which is higher than the first clock rate (2&pgr;/&Dgr;T1). When the target (2) reaches the tracking space (15), the tracking sensor (14) is aimed at the expected flight path (6) on the basis of the flight path data provided, the target (2) is detected as soon as it is detectable by the tracking sensor (14), and the tracking sensor (14) is tracked on the target autonomously.

Abstract: A system for the detection and determination of the success of interception of incoming missiles, used in conjunction with a defense weapon system capable of identifying and tracking incoming missiles and interceptors. The system comprises at least one of a plurality of sensing units. Each sensing unit comprises: an optical sensor for detecting optical signals within a predetermined range; tracking means coupled to the optical sensor for tracking an intercepting missile or an incoming missile; processing means for processing optical input detected by the optical sensor and analyzing the optical input to identify an optical signature and determine detonation of interceptor or incoming missile; communicating means for communicating data between the sensing unit and the defense weapon system; and control means for controlling the tracking means, the processing means and the communicating data.

Abstract: A system and method (32) for measuring line-of-sight angular rates for all-weather precision guidance of distributed projectiles (16) and a guidance system (10) based thereon. In accordance with the novel method (32) for measuring line-of-sight angular rates, first the range rates of the target (14) relative to at least two projectiles (16) is determined, as well as the position and velocity of each projectile (16). Then, the line-of-sight angular rate of the target (14) relative to at least one projectile (16) is computed from the range rates, positions, and velocities. In the illustrative embodiment, the range rate of the target (14) relative to a projectile (16) is determined based on a monostatic target Doppler measurement, a monostatic projectile Doppler measurement, a bistatic Doppler measurement of the target (14) by the projectile (16), and the carrier frequency of a data link (26) between the projectile and the shipboard system.

Abstract: A system and method for detecting a target. The inventive method includes the steps of receiving a complex return signal of an electromagnetic pulse having a real and an imaginary component; extracting from the imaginary component information representative of the phase component of the return signal; and utilizing the phase component to detect the target. Specifically, the phase components are those found from the complex range-Doppler map. More specific embodiments further include the steps of determining a power spectral density of the phase component of the return signal; performing a cross-correlation of power spectral density of the phase component of the return signal between different antenna-subarray (quadrant channels); and averaging the cross-correlated power spectral density of the low frequency components. In an alternative embodiment, the cross-correlation is performed on the phase component of the range-Doppler map directly.

Abstract: An active short pulse fuze system for arming on a true target acquisition and firing only on the loss of the acquired target signal. The sea surface is tracked by means of a sea tracking loop A target threshold is established and is coupled to the sea tracking loop so as to expand and contract with the sea tracking. A return signal will pass the target threshold only when there is an abrupt reduction in range, indicating the presence of a target. The presence of this signal will arm the firing circuit. An abrupt increase in range will indicate the loss of the target and cause immediate detonation of the warhead.

Abstract: A method and bistatic synthetic aperture radar (SAR) imaging system generate an image of a target area without knowledge of the position or velocity of the illuminator. The system includes an illuminator to illuminate a target area with a null-monopulse radiation pattern interleaved with a sum radiation pattern. The illuminator adjusts the phase terms of the sum radiation pattern to maintain a static electromagnetic field pattern at the target area. A receiver receives the radiation patterns reflected from the target area and generates phase compensation terms by correlating a measured electromagnetic vector field with the known static electromagnetic vector field. The phase compensation terms are used to generate an image of the target area.

Abstract: A combined defense and navigational system on a naval vessel is disclosed. The disclosed system includes a track-while-scan pulse radar which is controlled to provide either navigational information or tracking information on selected targets. Additionally, the disclosed system includes a plurality of guided missiles, each of which may be vertically launched and directed toward intercept of a selected target either by commands from the track-while-scan radar or from an active guidance system in each such missile.

Abstract: In a radar system, sampled aperture data are received from an antenna array. The sampled aperture data include data that do not correspond to echo returns from a beam transmitted by the antenna. A covariance matrix is generating using the sampled aperture data. An eigenvalue decomposition is performed on the covariance matrix. A direction of arrival is determined from which at least one jammer is transmitting a signal included in the sampled aperture data, based on the eigenvalue decomposition.

Abstract: A radar system and method for detecting and tracking a target of interest in the presence of interference, wherein the interference emits interfering signals, includes a receiver for receiving the interfering signals directly from the interference. The receiver also receives reflected signals, wherein the reflected signals is the interfering signals reflected by the target of interest. The interfering signals and the reflected signals are compared to detect the target of interest. In one embodiment, the reflected signals and the interfering are cross-correlated. The results of the cross-correlation are used to obtain range, position, and velocity information about the target of interest from a range/Doppler map.

Abstract: A wideband adaptive digital beamforming technique for maintaining a high range resolution profile of a target in motion in the presence of jamming utilizes a sequence of adaptively calculated narrowband jamming cancellation weights. The adaptive weights are calculated such that the desired frequency dependent gain is maintained toward the target center. These adaptive weights tend to preserve the range profile quality and low range sidelobes. This technique also tends to eliminate signal cancellation problems as well as adaptive weight modulation effects.

Abstract: In a system for estimating the launch point of a missile, Doppler shifted signals reflected from the missile as it travels from its launch point are used in a Kalman filter to estimate the missile position, velocity and acceleration, in earth centered fixed coordinates. The coordinate system is rotated to a rotated earth fixed (REF) coordinate system in which the X-axis passes through the estimated missile launch point and the Z-axis is made parallel to the missile azimuth as represented by the missile velocity determined by the Kalman filter. The error in the downrange component of the missile launch point is then reduced to a minimum in the REF coordinate system using a square root information filter. The coordinate system is then rotated to a second rotated earth fixed coordinate system in which the X-axis passes through the updated launch point position and the Z-axis is positioned at 45 degrees from the missile azimuth.

Abstract: Disclosed is a method and apparatus for improving airborne vehicle tracking and guidance systems by reducing boresight error induced by polarization of the RF energy impinging on the vehicle radome. The radome wall is formed with a taper which gradually increases from the base near the vehicle antenna to the tip according to a disclosed formula which accounts for frequency, incidence angle, look angle, and the dielectric constant of the radome material. This taper of the radome minimizes the crossplane boresight error component magnitude which is polarization sensitive and produces a polarization insensitive inplane boresight error component. Also disclosed is a method of electronically compensating such radomes for boresight error where the radome boresight error data accumulated during testing is digitized and processed for compensating data in the vehicle electronic system to provide compensated tracking data for the vehicle guidance system.

Abstract: A tracking method for a signal echo system, including generating a plurality of gates for respective propagation modes on the basis of a target state prediction for a dwell time, and generating a target state estimate for the dwell time on the basis of target measurement points which fall within the gates.

Abstract: Methods of associating a first target track and one of a group of target tracks measured by a radar system, in which the first target track is compared with each of the target tracks in the group of target tracks based on movement between two selected target positions, one in each of the two target tracks. Predetermined maximum numbers of changes in target parameters such as course and speed are assumed to have been able to take place during the movement, and a target parameter for the two positions is allowed to vary while other target parameters are kept constant. A possible range for the varying parameter is determined that is consistent with movement between the two positions, and if a measured value of the varying parameter lies within the range, target tracks are associated with each other.

Abstract: A system (10) for determining the range between a missile (14) and a target (18) adapted for use with a semi-active missile system. The system (10) includes a first circuit (12) for generating a periodic signal (24) that is periodically frequency modulated. A second circuit (16) determines a closing rate at which the missile 14 is approaching the target 18 via the periodic signal 24. A third circuit (16) determines a value containing information corresponding to the range and the closing rate via the periodic signal. A fourth circuit (16) determines the range from the closing rate and the value. In a specific embodiment, the first circuit (12) includes an illumination system (12). The illumination system (12) includes a periodically modulated carrier signal generator (32) that generates the periodic signal (24). The periodically modulated carrier signal generator (32) includes a frequency source, a frequency modulator, and an illumination system computer.

Abstract: A search radar including the improvement of apparatus for enhancing the estimation of the target angle within a search scan of the radar is disclosed. More specifically, the improvement apparatus utilizes the generated scan angles and target amplitude measurements correspondingly associated therewith to generate intermediate signals which are representative of the natural logarithm of the target amplitude measurements plus the square of the corresponding scan angle multiplied by a predetermined constant. For each search scan, the apparatus computes separately signals representative of the moments of: the scan angles, the squares of the scan angles, the products of the scan angles and corresponding intermediate signals, and the intermediate signals. In turn, the apparatus operates on the computed moment representative signals in some prespecified mathematical relationship to effect an optimum estimation for the target angle in each search scan of the radar.

Abstract: A monopulse antenna system comprising an inner antenna and an outer antenna disposed symmetrically about a central axis of symmetry. A central aperture is located at the axis of symmetry through which a weapon system may fire or an additional sensor may be located. The inner antenna is preferably annular in shape and produces a relatively broad antenna pattern. The outer antenna is also preferably annular and produces a beam pattern with many lobes. The received signals A and B, from each beam pattern, are combined in a hybrid to produce sum signals (A+B) and difference signals (A−B), which are then processed to produce a target off-axis radius relative to the antenna main beam axis, i.e., the axis of symmetry.

Abstract: An efficient receiver system (80) adapted for use with a pulsed radar system. The receiver system (80) includes a first circuit (82) for receiving a first signal and providing a second signal in response thereto. A second circuit (96) compares the second signal to a predetermined sequence (98) and provides a compare signal in response thereto. A third circuit (104) stores information pertaining to the second signal in response to the compare signal. A fourth circuit (92) generates receiver system instructions based on the stored information. In a specific embodiment, the second signal is a digital signal and the sequence is a digital sequence. The pulsed radar system includes a circuit for receiving and collecting data during a first dwell and for processing the data during a subsequent dwell. An inter-dwell time interval exists between the first dwell and the second dwell. The first, second, third, and/or fourth circuits (82, 96, 104, and/or 92) operate during the inter-dwell period.

Abstract: A method of operating a radar to track echo signals from a target in the presence of a barrage jammer is shown to comprise the steps of actively determining the apparent direction of the combination of echo signals from a target and jamming signals, passively determining the actual direction and average power of a barrage jammer, calculating, from the foregoing, the actual direction of the target and instituting range and angle tracking of the target when the target is clear of the jamming signals.

Abstract: A means for identifying a particular range and Doppler shift signal in the field of view of a moving radar antenna which determines azimuth angle to this range-Doppler signal relative to the antenna by determining the phase difference between said signal as processed through two channels each fed by antennas displaced in a horizontal direction with respect to the axis of the antenna system.

Abstract: A phased array radar system for target tracking having a track initiation unit, a track prediction unit, a scheduling unit, a track selection unit, and a transmitter/receiver unit. The track initiation unit initiates new tracks representing detected aircraft targets. The track prediction unit predicts the expected position and the calculated position uncertainty of the target as a function of time and the minimal, maximal and optimal time difference to the next measurement. The scheduling unit performs an independent calculation of a sequence of possible time intervals to the next measurement in accordance with specified conditions, and then performs an intersection operation between the calculated sequences of time intervals in order to calculate the optimal time interval to the next measurement. A track selection unit selects that track which has the shortest remaining time interval, K.sub.i, to the next measurement and decreases the time interval to the next measurement for all other tracks with K.sub.i.

Abstract: A process and a system for selecting a pulse repetition frequency that causes clutter pulse repetition frequency lines from the negative carrier frequency and from the clutter harmonic frequencies to lay on top of clutter pulse repetition frequency lines from the positive carrier frequency. A pulsed Doppler radar receiver of the system has one or more channels each comprising of a radio frequency input section for receiving a radio frequency carrier. Following the radio frequency input section are one or more serially arranged intermediate frequency sections that terminate in a last intermediate frequency section. The last intermediate frequency section is followed by analog-to-digital conversion and down-conversion to baseband in-phase and quadrature channels. In-phase and quadrature data from the in-phase and quadrature channels is processible by a computational system to detect and track a target in the presence of clutter.

Abstract: Method and apparatus for the detection of a target receiver unit such as an enemy radar or radio receiver is disclosed. The surveillance system of this invention includes a transmitter unit coupled to an antenna to establish an electromagnetic surveillance field that includes signal components at two predetermined surveillance frequencies. When a target receiver is located within the surveillance field, the target receiver produces a second electromagnetic field having signal components at the intermodulation products of the surveillance field signal components due to a nonlinear mixing process that occurs within the target receiver. Signal components at predetermined intermodulation frequencies are detected by a receiver circuit within the surveillance system that has a passband excluding signal components at the two predetermined surveillance frequencies.

Abstract: A method for guiding a missile to a target. The method includes the step of providing a surface-based radar system having an electronically beam steerable antenna system adapted for continuous mechanical rotation about an axis. During a pre-terminal, semi-active missile homing guidance phase, the beam produced by the antenna system is electronically rotated by the antenna system in a direction counter to the direction of the mechanical rotation of the antenna system to thereby increase radar system illumination time on the target. Further, during the increased illumination time, the beamwidth of the surface-based radar system beam is increased. During, a subsequent terminal, active homing missile guidance phase, guiding the missile to the target with the pre-terminal, semi-active missile homing guidance phase using the surface-based radar system and establishing an angular orientation for a missile-borne antenna system at the commencement of the terminal, active missile homing guidance system phase.

Abstract: A method for calibrating the radar system includes the steps of: replacing stored statistically generated "average" error correction coefficients with error correction coefficients personal to a missile under test. More particularly, stored in the missile's memory are: (a) first personalized error correction coefficients generated in response to test signals produced internal to the missile and injected into a monopulse arithmetic unit for the missile's receiver/processor; and (b) a second set of personalized error coefficients generated in response to test signals external to the missile and injected through the missile's antenna to the receiver/processor. The missile includes a radio frequency (R.F.) energy test signal generator for performing a test during the missile's flight to determine "in-flight" personalized error correction coefficients. The test is performed in-flight by injecting the R.F.

Abstract: The process and the corresponding phase or amplitude-single pulse radar device are used to locate a first and possibly a second target (TT1, TT2) detected by the radar beam from the direction x1, y1; x2, y2. The extended single-pulse aerial of the radar device has at least three partial aerials for a first measuring axis x (e.g. azimuth) which are arranged in such a way, have such directional characteristics and the signals of which are combined together and weighted in such a way that two mutually linearly independent, purely real or purely imaginary aerial functions which are independent of target displacements perpendicular to the first measuring axis are formed. The function course of these aerial functions F1(x) and F2(x) is measured for the individual case and the functional values dependent upon the target displacement x are stored in the storage unit (MEM). Measurements are found for the targets of the position x1 and x2 detected by the radar beam according to the aerial functions F1 and F2.

Abstract: The volume of space, in range, azimuth and elevation, over which a conventional Tactical Ballistic Missile (TBM) early warning radar is required to search for incoming missiles is very large. This placed very heavy demands on the radar designer, resulting in large, very high power, low mobility radars, with subsequent vulnerability to ARMs and other defence suppression systems. This invention proposes an alternative approach to a TBM early earning radar which considerably reduces both the design and vulnerability problem, and permits effective TBM early warning radars to be constructed using current technology. This is achieved by moving the radar (1) beyond the front edge of the defended area (2). The increased elevation scan requirements are more than compensated for by a range-adaptive scanning technique which reduces the volume search time by more than 50% compared with a more conventional arrangement.

Abstract: A radar tracking system 100 adapted for use with existing radar tracking systems. The inventive system includes a radar target detection system 106, 108 for detecting radar targets in clutter using magnitude and angular position information obtained from return signals. A tracking algorithm 104 is used to track and update the positions of said targets with respect to the position of the radar system. The tracking algorithm includes a true target angle estimator 110 for maintaining accurate target angle information when the target is clutter and when the target is out of clutter. The tracking algorithm maintains accurate target distance information when the target is in clutter and when the target is out of clutter. In a specific embodiment, accurate distance information is maintained in a track file 122 where the amplitudes of return signals are stored once a target is detected by the detection system 100.

Abstract: A coherent radar receiver that has pulse-to-pulse coherence using an unlocked voltage controlled oscillator, such as a Gunn voltage controlled oscillator. The present invention is a W-band, for example, bistatic receiver that uses a scanning sum channel antenna to scan the target, a downconverter for downconverting received alternating sum and difference pulse echoes from the bistatic illuminator to provide video signals, and processing circuits for processing the downconverted the video signals to precisely locate the null position on the target. A Fourier transform circuit, magnitude detector and a peak detection and centroid circuit are used to generate a voltage frequency control output signal that is applied to the voltage controlled oscillator or local oscillator that controls its frequency. An angle estimation algorithm is used that processes the video signals to locate the null offset from the center of a scan pattern generated by the antenna.

Abstract: A radar system in which a frequency agile synthesizer is used to provide rapid frequency shifts and in which measures are taken to maintain phase coherency. The system is fully coherent such that all signals are derived from a common source and are capable of high pulse repetition rates in excess of 1 MHz. There are no inherent transmit duty cycle restrictions and the system is able to transmit complex phase and frequency modulated waveforms. A frequency interleaving scheme is used to resolve range ambiguities at high pulse repetition frequencies and the use of a complementary phase coding scheme allows a high range resolution processing with the transmitted waveforms.

Abstract: A maneuver detector and processing method for use in target trackers employed in weapon guidance systems, and the like, that employs multidimensional measurements and a set of inertial coordinate systems. The maneuver detector and processing method are implemented as follows. Time-delayed target position and velocity estimates of the target are maintained in a history file. These estimates are continuously updated, in that they are transformed 24 into intermediate north, east, down (NED) range Cartesian coordinate systems by correcting for aircraft motion. For each measurement time, the histories are used to predict the position and velocity of the target in an "observation-relative" inertial coordinate system aligned with the line-of-sight to the target. The error between the prediction and observation is calculated and used with the measurement accuracies to calculate a maneuver probability.

Abstract: A radar system is provided to track radar energy reflected by a point on the target different from the centroid of a target's radar reflected energy. The radar system includes a target angle/range tracking system and a target energy monitoring/range tracking system. During a first mode of operation, the target angle/range tracking system tracks the centroid of the target's reflected energy; and, the target energy monitoring/range tracking system monitors the strength of energy reflected from points, or regions along the body of the target different from the centroid reflected energy producing region. When the signal strength to noise ratio (i.e., S/N ratio) from a reflection at one of the monitored points along the target exceeds a predetermined level indicating detection of a secondary reflector along the body of the target, a second operation mode commences.

Abstract: A radar system includes a radar receiver that provides the amplitude and the angular position of a plurality of return signals. A computer forms a test function of amplitudes and angular positions of the plurality of return signals and compares the test function with a threshold value. Returns associated with a test function whose value is equal to or greater than the threshold value are determined to be targets, and those with lesser values are considered clutter.

Abstract: A probe acquisition and display system is disclosed featuring one simple trol for acquiring, tracking, and instantaneously locking for a missile control radar. The system provides for fast initial target acquisition and re-acquisition in the presence of intentional or unintentional interference. A dual trace oscilloscope display is provided with radar tracking (range) gate and a probe is used to touch a target on the display by a radar operator.

Abstract: A moving target which is reflecting waves will give rise to the well known Doppler frequency shift. When the reflected signal can be compared with the transmitted signal in homodyne detection, the resulting signal is called the Doppler signal. Both frequency and phase of the Doppler signal carry information about the motion of the target.By observing a Doppler signal at several points in space, it is possible to determine the position, velocity and acceleration of a moving target. Systems employing this principle are-used to track acoustic emitters with sonar, as well as radio emitters with radar. While the prior an has relied on analyzing the Doppler shift frequency, the present invention introduces a method employing the analysis of the phase of the Doppler signal. The phase-based algorithm shows a better signal to noise ratio in applications where the ratio of velocity and distance to the point of closest approach is large.

Abstract: Target tracking basic sensors are used alone or in multi-sensor combination for multi-target surveillance systems. Optimal assignment of targets to pseudo sensor combinations of single basic sensor groups or to sensor groups formed of a plurality of basic sensors is provided subject to given constraints on basic sensor capacity for a given definition of optimal. The approach taken here is to determine the predicted gain in information content of a track i after it is updated with data from pseudo sensor i for all pairs i,j. This information content is then used to predict without making actual observations by using the properties of the Kalman covariance matrix. Assignments of tracks to pseudo sensors are then made on a continuing basis so that the total information gain is maximized. This is achieved by imposing unique constraints on the pseudo sensors and then calculation maximized information gain using linear programming methods.

Abstract: This invention comprises the use of integral pulse frequency modulation (IPFM) reaction jet controllers for multi-axis precision tracking of moving objects with flexible spacecraft, and vibration suppression. Two sets of position, rate and accelertion command profiles for multi-axis tracking are disclosed: one for a payload initially facing the zenith and the commands based on a pitch-roll sequence; the other for a payload facing the nadir and the commands based on a roll-pitch sequence. The procedure for designing an IPFM controller for tracking a given, inertial acceleration command profile is disclosed. Important elastic modes of a spacecraft are identified according to their spontaneous attitude and rate response to the minimum impulse bit of the thrusters. The stability of the control-structure interaction is shown to be governed by the ratio of the moments of inertia of the flexible to the rigid portions of the spacecraft.

Abstract: A radar system including a Kalman filter that processes radar return signals to produces position, velocity, acceleration, gain and residual error output signals, and a post-processor that processes these signals in accordance with a track filter bias estimation procedure. The procedure computes bias estimates and revised position, velocity and acceleration output signals that are corrected for bias error. The revised output signals are coupled to the radar system to track a target. The track filter bias estimation method computes bias estimates in accordance with the relationship: ##EQU1## where Res, K.sub.1 /K.sub.2, R and T denote the residual, gains, range, and filter cycle time, respectively, and the tilde indicates a sample averaging. The present invention also provides for improved maneuver detection by implementing an acceleration estimation algorithm used to track a maneuvering target. The present invention is applicable in all fields and areas where estimation using Kalman filters is used.

Abstract: A system and method that uses differential computation of position relative to a global positioning system (GPS) coordinate system and the computation of an optimum weapon flight path to guide a weapon to a non-moving fixed or relocatable target. The system comprises an airborne platform that uses a navigation subsystem that utilizes the GPS satellite system to provide the coordinate system and a synthetic array radar (SAR) to locate desirable targets. Targeting is done prior to weapon launch, the weapon therefore requires only a navigation subsystem that also utilizes the GPS satellite system to provide the same coordinate system that the platform used, a warhead and a propulsion system (for powered weapons only). This results in a very inexpensive weapon with a launch and leave (autonomous) capability. The computational procedure used in the platform uses several radar measurements spaced many degrees apart. The accuracy is increased if more measurements are made.

Abstract: An adaptive RADAR environmental signal filter (1) is described which selectively preprocesses RF RADAR input data prior to the data's utilization by a processor (8). The filter (1) consists of an array of parallel discriminator cells (165) which compare incoming RF RADAR data to a window parameterized by predetermined threshold values. The array of discriminator outputs are networked through combinational logic (59) in order to provide an output correlation signal (63) to an external processor (8). A discriminator enable latch (55) synchronizes the discriminator outputs as the outputs pass through the combinational logic (59).

Abstract: A method and apparatus for detecting an object of interest against a cluttered background scene. In a first preferred embodiment the sensor tracking the scene is movable on a platform such that each frame of the video representation of the scene is aligned, i.e., appears at the same place in sensor coordinates. A current video frame of the scene is stored in a first frame storage device (14) and a previous video frame of the scene is stored in a second frame storage device (20). The frames are then subtracted by means of an invertor (24)and a frame adder (28) to remove most of the background clutter. The subtracted image is put through a first leakage reducing filter, preferably a minimum difference processor filter (32). The current video frame in the first frame storage device (14) is put through a second leakage-reducing filter, preferably minimum difference processor filter (36).