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: An ADPCA subsystem includes a weight processor for weighting the delta channel signal according to the results of an adaptive algorithm to which the output of a DPCA vector combiner is input. An AMTI vector combiner is connected to the output of the DPCA vector combiner to form the filter output. The delta channel signal is time delayed and samples of the delta channel signal are collected by the processor together with a sum channel sample and a residue sample, in order to apply the proper weights to the undelayed and delayed delta channel samples. The output of the ADPCA weight processor therefore provides an optimum correction signal to the vector combiner.

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: In an FMCW radar system, the velocity of obstacles relative to the radar couples a Doppler frequency shift into the return signal which causes an error in the range measurement. It is known to use a radar signal having a frequency ramp that both increases and decreases to distinguish the range of an obstacle from its velocity but when multiple obstacles are present this is not practical. By using a measure of velocity from a succesion of return signals, which of the radar output signals from the upsweep and downsweep of the radar signal that relate to a particular obstacle can be identified so that the range and velocity can be determined accurately. The FMCW radar system may be provided with a frequency scanned antenna, the beamwidth determined by the processing circuitry is variable according to the size of the obstacle being detected or the range at which the radar is searching for obstacles.

Abstract: A method and system for real-time tracking of objects is disclosed. A region is repeatedly scanned providing a plurality of images or data sets having points corresponding to objects in the region to be tracked. Given a previously determined track for each object in the region, an M-dimensional combinatorial optimization assignment problem is formulated using the points from M-1 of the images or data sets, wherein each point is preferably used in extending at most one track. The M-dimensional problem is subsequently solved for an optimal or near-optimal assignment of the points to the tracks, extending the tracking of the objects so that a response to each object can be initiated by the system in real-time. Speed and accuracy is provided by an iterative Lagrangian Relaxation technique wherein a plurality of constraint dimensions are relaxed simultaneously to yield a reduced dimensional optimization problem whose solution is used to formulate an assignment problem of dimensionality less than M.

Abstract: Disclosed is a method for the management of the beam of an electronically scanned rotating antenna. For each antenna rotation, the sequencing of the commands is organized in three phases associated with zones of the space: a first phase of preparation of the requested aiming operations before their entry into the visibility cone of the antenna; a second phase of carrying out the requested aiming operations present in the visibility cone; a third phase of identifying the requested aiming operations that have come out from the visibility cone and have not been carried out. Application to multi-function radars.

Abstract: A method for tracking objects is disclosed. First a region containing the objects is scanned to generate a multiplicity of sequential images or data sets of the region. A plurality of points in each of the images or data sets corresponds to a respective plurality of the objects. Next, respective figures of merit are determined for assigning the points to the tracks. Next, a k-dimensional cost function is defined which sums the figures of merit for combinations of assignments from the images or data sets. Next, the complexity of the cost function is reduced by Lagrangian Relaxation by permitting a point to be assigned to more than one track and adding a penalty factor to the cost function when a point is assigned to more than one track. The reducing step is iteratively repeated and the resultant penalized cost function is solved.

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 target tracking system (10) comprises sensors (12) which provide data corresponding to a region of interest, the data being time dependent and consisting of amplitudes, ranges and angles. A window (202) is placed around data of interest, the size of the window being determined based on target size, assumed speed and acceleration characteristic, and the window is thereafter broken down into a plurality of smaller windows (208), thereby forming a grid having a nodal point (210) at each corner of the smaller windows. The data within the window is stored in a matrix, and background noise is thereafter minimized by filtering the data past a threshold value (215). The filtered data is analyzed to determine its distance weighted contribution at each nodal point (219), and the weighted distances are summed for each nodal point resulting in a nodal point magnitude for each of the nodal points (220).

Abstract: A filtering system used in the tracking of a maneuvering target is provid A first filter estimates a partial system state at a time k in terms of target position measurements. A plurality of second filters are each provided with an acceleration model hypothesis from a prior time (k-1) free of position and velocity constraints. Each second filter generates an acceleration estimate at time k and a likelihood at time k that the acceleration model hypothesis is correct. The likelihoods from the second filters are summed to generate a probability vector at time k. A third interaction mixing filter generates the acceleration model hypotheses from prior time (k-1) using the probability vector from prior time (k-1) and the acceleration estimates from prior time (k-1). The third filter also provides an error covariance to the first filter to reflect the uncertainty in the acceleration model hypotheses from prior time (k-1).

Abstract: A search radar system, is provided which includes at least one search radar device (1) having a primary antenna (2) and at least one secondary radar device (3) having an SSR/IFF antenna (4). The radar devices (1, 3) independently supply plot data from which signals are derived that are each suitable for presentation on a radar display. The antennas (2, 4) are oriented in opposite directions so that the said signals are derived from individual plot data representing successive detections by the respective antennas of the same target which can be individually presented. Hence, the data rate of the radar system is doubled relative to a conventional radar system having a conventional secondary radar device and a conventional antenna system.

Abstract: A process for reducing the likelihood of runway incursions wherein the major components of an aircraft are individually tracked by radar instead of tracking only the overall image of the aircraft to more accurately predict possible runway incursions due to the rapid and accurate indication of any change in aircraft orientation during each sweep of the radar.

Abstract: A method of reducing tracking errors in an area comprised of touching surveillance regions which involves; transmitting a plurality of signals into a region, receiving signals scattered from the region and analyzing the received signals using a processing means, to produce target measurements; dividing each region into a number of zones comprising an edge zone at each edge of said region and one or more center zones; associating target measurements with appropriate zones; apportioning said measurements into data blocks on a storage means such that each pair of adjoining edge zones form a single data block and each central zone forms a data block; updating target tracks in each data block using said target measurements; allocating target tracks from each data block to the correct region; and displaying the tracks on a visual display means. A separate list of tracks for those targets contained in the edge track zone of touching regions is maintained.

Abstract: A vector neural network (VNN) of interconnected neurons is provided in transition mappings of potential targets wherein the threshold (energy) of a single frame does not provide adequate information (energy) to declare a target position. The VNN enhances the signal-to-noise ratio (SNR) by integrating target energy over multiple frames including the steps of postulating massive numbers of target tracks (the hypotheses), propagating these target tracks over multiple frames, and accommodating different velocity target by pixel quantization. The VNN then defers thresholding to subsequent target stages when higher SNR's are prevalent so that the loss of target information is minimized, and the VNN can declare both target location and velocity. The VNN can further include target maneuver detection by a process of energy balancing hypotheses.

Abstract: A method and apparatus for reducing the calculations necessary to track a mber of targets. The invention trades off the magnitude of search radius in parameter space against the number of extra copies made of the track data structure in a manner that inherently saves computation as the number of targets becomes large.

Abstract: A method and apparatus for generating a track data set corresponding to a plurality of objects. A system employing the invention receives reports, e.g. radar echoes, from the plurality of objects over a time interval, partitions the time interval into subintervals or time bins, and sorts the returns into the time bins. In each bin, the reports are very close to one another in time, so that, in correlating the reports in each bin to the tracks, one can use the reports to form the necessary search tree, rather than using the tracks. Doing so increases efficiency if the number of reports per time interval significantly exceeds the number of tracks.

Abstract: A technique is disclosed for multiple sensor tracking which distributes data association and filtering processing among multiple processing entities but coordinates the track estimates such that track states and covariances represent the equivalent of a centralized estimate. The object of the invention is to establish and maintain a single system track for a single aircraft in a distributed processing environment. This is achieved through communication of track information among processing entities which process a single sensor's inputs. Continued updating and re-broadcasting of process data are performed between the multiple sensor's processing entities.

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: The Dual Function Radar Receiver shown provides hardware commonality between detection and tracking modes. Four channels (56, 58, 60, 62) are provided, each of which searches a separate range bin during the detection mode. During the tracking mode, one channel (56) continues to search a range bin, while the second channel (58) servos the range bin to the range of the detected object. The third channel (60) processes the azimuthal difference signal (94), and the fourth channel processes the elevational difference signal (110).

Abstract: A method of managing beams transmitted and received by a plurality of phased array antennas. In a search mode, the phased array antennas transmit searching pulses synchronously in a search mode. In a tracking mode, targets tracked by the phased array antennas are divided to a plurality of groups on the basis of pulsed repetition rate. Then, for the respective divided groups, transmission timings of tracking pulses to be sent form the phased array antennas are calculated by using ranges of the targets belonging to the respective groups so that transmission and reception operations do not occur simultaneously, thereby enabling the simultaneous usage of the phased array antennas.

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: A radar system for tracking a plurality of individual objects that form a cluster. The system comprises means for producing in real time reference information indicative of the position of a reference point associated with the mean position of the objects, and means for producing in real time displacement information indicative of the relative position of each object with respect to the reference point. The system may handle a transmitter, and the means for producing the displacement information may include a interferometer system comprising a central receiver, a pair of first satellite receivers positioned on opposite sides of the central receiver along a first axis that passes through the central receiver, and a pair of second satellite receivers positioned on opposite sides of the central receiver along a second axis that passes through the central receiver and that is inclined with respect to the first axis.

Abstract: A mode scheduling system for selecting track or search dwells in a track-while-scan radar. Targets to be tracked are classified according to acceleration levels and then arranged into priority classes based upon the acceleration. A relative update frequency for the targets in the priority classes is established. The track and search dwells are made during a repetitive dwell period having a predetermined number of track dwell intervals. Track dwells are scheduled during these intervals to satisfy the update frequency requirements. When all of the track dwell positions are not needed, search dwells are substituted for some of the track dwells. Search dwells are also inserted between track dwells, as needed, to maintain a minimum amount of search time regardless of the number of targets being tracked.