Abstract: A distance measurement device comprises at least one switch for generating a start signal, a distance measurement device for measuring the distance to an object in response to the start signal, a memory device for storing distance data measured by the distance measurement device, the stored data defining a plurality of measurement zones within the full range of distance measurement of the distance measurement device, and a judgement circuit for judging which measurement zone the result of the distance measurement performed by the distance measurement means belongs to from the plurality of measurement zones defined by the distance data stored in the memory device. In accordance with this configuration, division points can be set if an object is placed at an actual division point desired and a switch is pressed. Accordingly, when an operator sets the division point, it is unnecessary to depend on memory, perception, or calculation, and the setting of the division points becomes easier.

Abstract: A radar apparatus having a phased array antenna with a large number of transmit and receive modules, a control unit and a video processor. The control unit generates a number of pulse bursts per azimuth-elevation direction, all of which shows slight carrier frequency differences. The video processor determines a doppler spectrum and compared successive spectra for each pulse burst. As a result of the frequency differences, clutter does not show much of a shift while targets which are subject to fold-back in the frequency domain will show considerable shift. A threshold based on a mean spectrum therefore enables detection.

Abstract: A system for obtaining digitized samples of an analog signal at a selectable rate, R. The system includes: a timing generator for producing a train of sampling pulses at a predetermined sampling rate, f.sub.s ; an analog to digital converter for producing a digitized sample of the analog signal in response to each one of the sampling pulses; a processor; and, a selector, for passing each Nth one of the digitized samples produced by the analog to digital converter, where N=f.sub.s /R to the processor. The selector includes a decimator, responsive to a signal, N=f.sub.s /R, representative of the ratio of the sampling rate, f.sub.s, to the digitized signal obtaining rate, R, for producing pulses at the rate, R=f.sub.s /N; and, a register for storing each Nth one of the digitized samples produced by the analog to digital converter, each one of such digitized samples being stored in response to a corresponding one of the pulses produced by the decimator.

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 plurality of threshold detectors is provided to pass analog signals of predetermined and varying threshold values. An analog to digital converter converts these analog signals to binary 1s and 0s. A target detected on each radar beam sweep is a 1 and no target is a 0. These binary numbers are then stored in a reversible up-down counter. At the first signal received, the counter counts up on hits (binary 1) and counts down on misses (binary 0). When the contents of the counter reaches a predetermined count, a target's leading edge is declared. At this time, the counter is then reset and proceeds to count up on misses and down on hits until the aforesaid predetermined count is attained, wherein a trailing edge is then declared.

Abstract: A cost-effective ultra-wideband band radar system capable of locating nearby buried objects such as reinforcing steel rods, pipes, and other objects buried in concrete, soil, behind walls, or in the air. A sequence of ultra-wideband band radar pulses are emitted without a carrier and the system detects deflected pulse energy caused by the transmitted pulse whenever encountering a change in the medium i.e. an air to metal change or concrete to metal change. This reflected energy is detected and visually displayed. The range gate delay is continuously varied, thus changing the distance from the unit to where the reflected energy would be potentially detected from the target. By continuously sweeping the "depth" of the scan, the operator need only move the unit in two dimensions across the surface to detect objects buried or hidden at varying depths interior to or behind the surface.

Abstract: The tracking of moving objects on land, in the air or at sea is effected by means of one or more sensors (S.sub.j.sup.1). The observation space of each sensor is divided into resolution cells (X.sup.1h) forming a grid. The sensors of the same grid are grouped together.A probability estimate (.beta.k) for a moving object being in a cell (Xk) which is an intersection of the resolution cells (X.sup.1h) is produced. For this purpose, the starting points are signals (M.sub.j.sup.1h) delivered by the sensors (S.sub.j.sup.1) and previously selected according to windowing criteria, sets of pairs (F.sub.i (M.sub.j.sup.1h)D.sub.ij.sup.1h) stored in memories (1) and coming from a prior supervised statistical learning, and tracking coefficients (.alpha.k) delivered by an adaptive tracking filter (4) of the PDAF type. After application of this probability (.beta.

Abstract: In a system for detecting the position and trajectory of a target, Doppler measurements from a bistatic continuous wave radar system are used exclusively to provide information about the target. Radar signals are transmitted to the target by a plurality of transmitters and at least one receiver is provided to receive the signals from the target and make Doppler measurements. A nonlinear least squares estimator is used to estimate the initial target position and a Kalman filter is used to predict the target trajectory from the initial position assumed by the NLS estimator and from the Doppler measurements. The Kalman filter also generates a set of predicted Doppler measurements from the predicted trajectory. The nonlinear least squares estimator is used to compute a correction to the estimated initial position from partial differentials of the initial position and from the differences between the predicted and actual Doppler measurements.

Abstract: A computer system and method for accurately transforming multiple returns received by multiple satellites from multiple targets into a set of single accurate tracks for each target. Observations from multiple satellites create partial or resulting tracks. These resulting tracks are then correlated with pre-existing base tracks by a series of steps in which resulting tracks are paired with pre-determined base tracks according to a series of criteria. Pairs based on: common observation points and time spans, common satellites, and lack of common satellite, are considered sequentially. The final attempt at correlation consists of pairing each remaining track with each base track and using profile dependent piece correlation of the pairs. Any remaining resulting tracks are then added to the set of base tracks.

Abstract: A method for estimating target parameters of a target with respect to a platform such as ownship includes assigning predetermined initial values for the target parameters, wherein the target parameters are part of models having respective model probabilities. The models may include a Kalman filter. The models are updated in response to measured parameters of the target, wherein the measured parameters are different from the ones to be estimated. After a predetermined number of updates, the model having the highest updated model probability may be selected as the winning model. The updated values of the target parameters in the winning model at the time of winner selection are used as the estimated values for the parameters sought to be estimated. The updated parameter values may be refined by restarting the process using the updated values of the winning model as the basis for assigning new initial values for the target parameters.

Abstract: A multiple hypothesis tracking system (10) which generates a substantially continuous output to a system user. The multiple hypothesis tracking system (10) generates a primary set of tracks (12) which best represents the expected number of targets of interest in a cluster. For multiple sensor applications, a secondary set of tracks is generated having a less probability than the tracks in the primary set. A knowledge of track data is maintained from one scan to a subsequent scan such that tracks can be merged and deleted (14). A universal track file (16) is generated in which track associations from one scan to a subsequent scan are correlated such that the output of the track file remains consistent with respect to the number of tracks.

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 laser speed detector is described which includes a laser rangefinder which determines the time-of-flight of an infrared laser pulse to a target and a microprocessor-based microcontroller. The device is small enough to be easily hand-held, and includes a trigger and a sighting scope for a user to visually select a target and to trigger operation of the device upon the selected target. The laser rangefinder includes self-calibrating interpolation circuitry, a digital logic-operated gate for reflected laser pulses in which both the "opening" and the "closing" of the gate can be selectably set by the microcontroller, and dual collimation of the outgoing laser pulse such that a minor portion of the outgoing laser pulse is sent to means for producing a timing reference signal.

Abstract: A system guides a vehicle along a predefined path by correlating vehicle side range profiles. A lead vehicle gathers side range data using active radiation sources such as light emitting diodes. A microprocessor-based system on board the lead vehicle stores the data into records of a database file, tagging each record to indicate a relative position along the path when the lead vehicle obtained the data. A system on board a follower vehicle gathers its own side range data and also generates a side range profile for the follower vehicle. The follower vehicle's system receives by radio communication the side range profiles from the lead vehicle and, using the tagging information, correlates these profiles with the follower vehicle side range profiles at appropriate points along the path.

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 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: The present invention relates to a pulse Doppler radar wherein the phase position of the reflected signals is evaluated as the most important component in addition to the amplitude. Thus a very good resolution results in the range direction and in the velocity direction for the detection of multiple target situations. The invention can be employed particularly for a so-called HPRF radar.

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 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 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: A video signal processor for a radar system includes A/D converters for receiving radar signals to digitize the signals at a predetermined speed, direct averagers for writing signals included in the predetermined size of azimuth among the digitized radar signals into different memories according to the azimuths and for averaging signals corresponding to the same range gates, cell average processors having a microcomputer and a RAM for cell-averaging the output of the direct averagers with the processing program down-loaded from a main controller, an extractor for extracting only target data from the output of one of the cell average processors, a radar video processor controller for generating various control signals, and a communication processor for performing the data transmission and reception between the main controller and the radar video processor controller of the radar system.

Abstract: An apparatus and method for tracking maneuvering and non-maneuvering targ in the presence of stochastic acceleration are provided. The apparatus and method utilize a two-stage Kalman estimator, the first stage of which is a bias-free filter providing target position and velocity estimates, and the second stage of which is a bias filter providing estimates of target acceleration. These two filters act together to provide parallel processing calculations thereby achieving high speed target state determination. During target maneuvers, the output of the second stage is used to correct the output of the first stage. In the absence of maneuver, the second stage is turned off and the first stage provides the target position and velocity estimates.

Abstract: A pulse Doppler radar altimeter designed to resolve the ambiguous range problem associated with the use of a pulse repetition interval, which is less than the aircraft altitude, includes a radar transmitter configured to transmit first and second series of pulses where the first series has a pulse repetition interval slightly different from the pulse repetition interval of the second series. At a time when the first series is being transmitted, the receiver electronics including a range gate and a tracker searches for ground returns and positions the range gate in time coincidence with the detected ground return. Control then shifts so that the second series of pulses is transmitted and a determination is made whether overlap of the range gate with the ground return from the second series corresponds to the same altitude as when the first series was involved.

Abstract: Range gate delay is effected by serially connected coarse and fine programmable delay lines. The radar transmit trigger pulse is propagated through the programmable delay lines to provide a delayed trigger pulse. The delayed trigger pulse triggers a range gate generator for generating the range gate. The delay effected by the coarse and fine programmable delay lines is controlled from the system CPU. The range gate generator comprises a D-type flip-flop with the Q output thereof connected as the input to a further programmable delay line. The delayed trigger pulse sets the flip-flop and the output of the further programmable delay line resets the flip-flop. The range gate is provided by the Q output of the flip-flop. The width of the range gate is determined by the delay set into the further programmable delay line by the system CPU.

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 pulsed doppler radar system having an improved detection probability, comprising an antenna unit, a transmitter for transmitting a signal through the antenna unit, a receiver for receiving a signal reflected by a target through the antenna unit to provide a reception signal. A processing unit which receives the reception signal from the receiver determines, in accordance with a range of the target and a signal-to-noise ratio and bandwidth of the reception signal, an optimum integration number which maximizes the detection probability and performs coherent integration on the reception signal by the number of times equal to the determined optimum integration number thereby outputting a signal having a predetermined level. Such a signal is fed to a display and an image of the target is displayed on a display.

Abstract: To make an "intelligent" selection, in a radar, of the piece of information transmitted to the tracking unit by the extractor, in case of saturation, a method comprising the first step of selecting a set of N attributes (x.sub.1, x.sub.2, . . . x.sub.N) defining the plots given by the extractor. Then quantifying each attribute, in defining intervals in the range of values taken by the attribute and associating, with each N-tuple formed by a combination of values of the attributes, an estimated value of validity of the corresponding plot. Further, for each plot transmitted by the extractor, searching for the N-tuple that corresponds to it, in order to associate the estimated value of validity, assigned to the N-tuple, with the plot.

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: A radar system for determining first time around targets from multiple time around targets using two radar pulse trains of different pulse repetition intervals and thresholding means. Echos from pulses at each pulse repetition interval being compared to determine first time around targets from subsequent time around targets. The radar system uses thresholding levels to determine an echo and is less prone to problems of coincidence gate clashing with high duty cycles.

Abstract: A processor adapted for use in conjunction with a monopulse radar system for discriminating between ground and airborne moving targets and comprising: Doppler filter circuits for detecting moving targets; angle measurement circuits which respond to the received sum and elevation difference signals so as to provide an indication of the relative angle of each moving target and of the ground; and means for identifying a detected target as a ground or an airborne target as a function of whether the angle of the target is substantially the same as or different from that of the ground.

Abstract: Post detection processing for a pulse doppler surveillance radar is disclosed wherein target reports having ambiguous ranges along with those containing unambiguous ranges are used for tracking targets. The tracking includes a maneuver recognition mechanism for adaptively weighting the range, range rate, and X and Y coordinate driving errors as a function of the maneuvering and non-maneuvering operations of the target.

Abstract: A radar system for low-level target tracking comprises a first and a second radar apparatus, both apparatus operating at their own frequency, but employing one and the same tracking antenna. A target being tracked in range and angle coordinates by the first radar apparatus can be tracked in angle coordinates by the second apparatus and in range by the first radar apparatus when the target arrives within the range of the second radar apparatus. A preferred digital embodiment of this system is obtained by utilizing a common signal processing unit including a matched filter.

Abstract: A modification is presented to improve radar systems, which normally tracks a single target, to enable them to perform a simultaneous search of a large space volume while maintaining track of a selected target. This modification entails an operating process in which a search is conducted with a controlled search pattern and search time so that the antenna is as close as possible to the tracked target position at the search conclusion and antenna slewing time is mimimized. Finally, the present procedure can be implemented while adding as little as a thousand words of memory to the radar system.

Abstract: A precision distance measuring equipment (DME/P) receiver for detecting an RF signal including at least one interrogation pulse is described. The DME/P receiver includes first and second signal processing channels. The first processing channel includes a wideband filter, of bandwidth BW1, for receiving the processed RF signal and in response thereto generating a wideband (FA) mode signal proportional to the logarithm thereof. The second signal processing channel includes a narrowband filter, of bandwidth BW2, for receiving the processed RF signal and in response thereto generating a narrowband (IA) mode signal proportional to the logarithm thereof, the bandwidth BW2 of the narrowband filter being within the bandwidth BW1 of the wideband filter.

Abstract: A process that derives estimates of range and range-rate during the radar ack of an object, when the radar employes a linear frequency modulated waveform. FM waveforms at the radar wavelength are transmitted. The frequency of the radar echos are measured and the difference between the incoming frequency of radar echos and the local oscillator frequency is estimated. The signal is decomposed into Range and Range rate. Implementation of the decomposition device can either be a sequence of stored software or a hardwired processor.