Abstract: A monopulse radar system generates elevation and azimuth difference monopulse estimates of the location of targets in each range cell, where the target may be either a single or plural target, each of which is made up of multiple scattering sources. Each azimuth-elevation estimate is based on a transmitted pulse or burst at a given frequency, different from other frequencies in a set of pulses or bursts. A test statistic is generated for each set. The statistic relates to the shape in an azimuth-elevation plane of the cluster of estimates. The test statistic is compared with a threshold to decide whether a single target or plural targets exist in the range cell.

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 method for target-tracking of objects via observations from a sensor, wherein a geographical region within which at least one object is present is divided into a predetermined number of states, and the geographical region is divided into subregions so that adjacently disposed subregions all contain a share of states in common. Target-tracking is initiated in a first subregion, whereupon a first observation is associated with the object, and the probable state of the object is estimated. For each new time interval, a new observation is chosen for which a new state is estimated, whereupon the estimated sequence of states in the subregion is updated. When target-tracking is begun in a new subregion, the state history from the preceding subregions is transferred to the new adjacent subregion so that the state estimate in the new subregion is based on the state history in the preceding adjacent subregions.

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 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&pgr;/&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: The present invention is directed to a system and method for Doppler track correlation for debris tracking in PCL radar applications. The disclosed embodiments describe the systems and methods used in the detection of debris pieces and the association of the Doppler signals from the debris pieces across multiple illumination channels. The present invention also provides computation of debris state vectors and the projection of trajectories to determine debris impact points.

Abstract: Portions of an input measurement sequence are classified into a plurality of regimes by associating each of a plurality of dynamic models with one a switching state such that a model is selected when its associated switching state is true. In a Viterbi-based method, a state transition record is determined, based on the input sequence. A switching state sequence is determined by backtracking through the state transition record. Finally, portions of the input sequence are classified into different regimes, responsive to the switching state sequence. In a variational-based method, the switching state at a particular instance is also determined by a switching model. The dynamic model is then decoupled from the switching model. Parameters of the decoupled dynamic model are determined responsive to a switching state probability estimate. A state of the decoupled dynamic model corresponding to a measurement at the particular instance is estimated, responsive to the input sequence.

Abstract: A radar comprising transmitter means for generating bursts of radar pulses, each scan of a radar consisting of a number (Nb) of bursts, the method comprises, for each scan k:

Abstract: A method analyzes a plan for scanning the content of a predetermined area. The method includes the steps of: providing a plan for at least one entity (200), the plan including a route and a set of scan points; and assigning an associated score for the plan in order to compare the plan to other plans, the score indicating the quality of the plan.

Abstract: A target in a sequence of measurements is tracked by modeling the target with a switching linear dynamic system (SLDS) having a plurality of dynamic models. Each dynamic model is associated with a switching state such that a model is selected when its associated switching state is true. A set of continuous state estimates is determined for a given measurement, and for each possible switching state. A state transition record is then determined by determining and recording, for a given measurement and for each possible switching state, an optimal previous switching state, based on the measurement sequence, where the optimal previous switching state optimizes a transition probability based on the set of continuous state estimates. A measurement model of the target is fitted to the measurement sequence. The measurement model is the description of the influence of the state on the measurement. It couples what is observed to the estimated target.

Abstract: Correlating observations of objects in the sky to determine an orbit includes identifying an initially identified object, determining if the initially identified object will be identifiable again, and identifying a subsequently identified object. A determination is then made by comparing characteristics of the initially identified object with the subsequently identified object. If the object correlate to one another a path or orbit of the object can be determined using the characteristics of the initially identified object and the subsequently identified object.

Abstract: An adaptive broadcast radar system for tracking targets is disclosed, the radar system includes a transmitter having sub-apertures and a receiver having sub-apertures. The transmitter sub-apertures generate and code a signal waveform. The signal waveform is coded with data about the transmitter, including the degrees of freedom. The receiver receives signals comprising direct path signals and scattered signals correlating to the signal waveforms from the transmitter. The receiver includes a signal processor that regenerates a transmit beam for the coded data, delay, and doppler information from the received signals. The signal processor generates data quads encapsulating the information.

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: This invention relates to an adaptive detection system and method for analyzing range-doppler-azimuth data for target detection. The detection system has a threshold calculator for calculating a threshold value that is based on the standard deviation of the range-doppler-azimuth data and a predetermined probability of detection. The detection system also has a detection module in communication with the threshold calculator to receive the threshold value. The detection module calculates an estimated target amplitude and an estimated noise floor amplitude based on the range-doppler data that is located in a detection window. The detection module detects a target when the difference between the estimated target amplitude and the estimated noise floor amplitude is larger than the threshold value.

Abstract: An HF radar system comprises a transmitting system, a receiving system, a signal processing system and a frequency management/ionospheric sounding system. The transmitting system comprises a transmitting antenna array configured to transmit a beam in a near vertical direction and a transmitting device arranged to drive the transmitting antenna array at frequencies suitable for downward refraction by the ionosphere. The receiving system comprises a receiving antenna array configured to receive returning signals from a target area returning to the receiving antenna array via refraction at the ionosphere. The signal processing system comprises a digital data processing system. The frequency management/sounding system comprises cooperating transmitting and receiving systems sending H-F signals to the ionosphere and analysing the returning signals. Alternatively, the system may have a duplexed antenna array.

Abstract: From a set of possible switching states and responsive to a sequence of measurements, a corresponding sequence of switching states is determined for a system having a plurality of dynamic models, associates each model with a switching state such that a model is selected when its associated switching state is true. A state transition record is determined, based on the measurement sequence. The sequence of switching states is determined by backtracking through the state transition record. Alternatively, the switching state model is decoupled from the dynamic system model. The decoupled switching state model is transformed into a hidden Markov model (HMM) switching state model, while the decoupled dynamic system model is transformed into a time-varying dynamic system model. A solution to the dynamic system model is estimated using a Kalman filter.

Abstract: A radar detection process includes computing a derivative of an FFT output signal to detect an object within a specified detection zone. In one embodiment, a zero crossing in the second derivative of the FFT output signal indicates the presence of an object. The range of the object is determined as a function of the frequency at which the zero crossing occurs. Also described is a detection table containing indicators of the presence or absence of an object within a respective radar beam and processing cycle. At least two such indicators are combined in order to detect the presence of an object within the detection zone.

Abstract: A system 100 is disclosed for monitoring the position of one or more RFID tags 201. The system has a detector 301 incorporating circuitry 304 for detecting changes in the range of an RFID tag 201 from the detector and for triggering an alarm 401 if a detected change in range of an RFID tag 201 exceeds a predetermined threshold or if the RFID radio tag cannot be detected by the detector 301. Range may be detected, for example, by measuring the time of a returned radio signal from a tag 201, by measuring the strength of a returned radio signal from a tag, or by detecting changes in a periodic interval at which energy is transmitted by a tag.

Abstract: A radar system and radar processing method includes a number of aspects for providing improved function. The system and method may employ one or more of the following aspects: timely range-velocity (range-Doppler) compensation for target nonstationarity by integration along hypothesized range-Doppler trajectories, allowing noncoherent integration over an elongated time interval; noncoherent integration of an enlarged signal set obtained from overlapped coherent processing intervals (CPIs); hypothesized joint multiple accelerations used to generate multiple hypothesized range-Doppler trajectories; and sliding window integration to increase data output rates with use of large noncoherent integration intervals (NCIs). These aspects allow for improved signal-to-noise ratios, for acquisition and tracking of targets at longer ranges, and for improved target parameter estimation.

Abstract: An adaptive radar scanning system for an aircraft includes a radar antenna that is angularly movable to scan across a full scan range. A control system operates the radar antenna to scan in an adjusted scan range based on information related to a heading of the aircraft. As a result, the radar system is able to provide more weather information in the direction of a turn, by truncating the scan range of the radar antenna in the direction away from the turn.

Abstract: A system and method for detecting and tracking a target object, including the calculation of the target object's altitude, is disclosed. During the processing of signals received by a receiver, the system selectively calculates the altitude of the target object from signals modified by an interference effect pattern formed by the signals broadcast by a transmitter, or from the calculation of geometric shapes associated with three or more transmitters and determining the intersection point of those shapes.

Abstract: Individual objects are located according to a coordinate system in time-successive patterns and correlated between patterns. The objects are correlated by assigning identifiers to each in both patterns. The locations are transformed by reorientation to their centroid. The average of the transformed coordinate differences is used to adjust the centroid of the objects in a subsequent pattern and the transformed coordinate differences adjusted for the centroid displacement. A figure of merit is taken as the root-mean-square of the adjusted differences and used to determine which possible combination of correlated objects between two patterns is most likely.

Abstract: Individual objects are located according to a coordinate system in time-successive patterns and correlated between patterns. The objects are correlated by assigning identifiers to each in both patterns. The locations are transformed by reorientation to their centroid. The average of the transformed coordinate differences is used to adjust the centroid of the objects in a subsequent pattern and the transformed coordinate differences adjusted for the centroid displacement. A figure of merit is taken as the root-mean-square of the adjusted differences and used to determine which possible combination of correlated objects between two patterns is most likely.

Abstract: A radar system (14, 20, 22) generates a plurality of data points (x, y) representative of the position of a tracked object (48), and a representation of an associated path (50, 60) is formed therefrom. At least one quality measure, and at least one heading measure, of said representation, is calculated corresponding to at least one map coordinate (44). The quality and heading measures are stored in memory as a track map. Data from other tracked objects (58) is used to update the track map (38), resulting a plurality of heading values at associated map coordinates (44) that are representative of a path (42) followed by the tracked objects (48, 58).

Abstract: The invention relates to a radar station placed on the surface of the earth, and to a radar system comprising at least two such radar stations. The signal-processing equipment of the radar stations is adapted, at each point of time, to calculate probabilities of target positions and radial target velocity in relation to each individual radar station, based on the signals emitted and received by this station. These calculated values are associated over time, giving cumulative probability measures for target positions and radial velocities in relation to each individual radar station. By providing a system of at least two radar stations, it is possible to calculate the position of a target by associating target positions, such as they are perceived by the different radar stations, with each other by an association of characteristic movements of the target. This is done without having to synchronize the stations.

Abstract: System and method for detection and tracking of targets, which in a preferred embodiment is based on the use of fractional Fourier transformation of time-domain signals to compute projections of the auto and cross ambiguity functions along arbitrary line segments. The efficient computational algorithms of the preferred embodiment are used to detect the position and estimate the velocity of signals, such as those encountered by active or passive sensor systems. Various applications of the proposed algorithm in the analysis of time-frequency domain signals are also disclosed.

Abstract: A timing and control method and apparatus (111) for performing precise range rate aiding includes a range gate delay means (114) for generating an estimate of the range gate delay (135) each pulse repetition interval as a function of the initial range (134) and velocity (133) provided by a processor (104). The range gate delay (135) is converted into a coarse delay (138) defining the integral number of clock cycles preceding the range gate, and a fine delay (139) for positioning a range gate to within a fraction of a clock cycle. Fine temporal control is achieved using programmable delay lines (117) and (118), which retard various control signals, including the system clock signal (131), in accordance with the fine delay (139). A modified signal (126) then drives a counter means (119) which outputs a signal (128) that defines an analog-to-digital sampling window beginning at the elapse of the range gate delay (135).

Abstract: The present invention is in general related to target type estimation in target tracking systems. The invention enables a low complexity estimation of target type, using, e.g. ESM sensor data, by the introduction of an ambiguity restoring procedure in certain likelihood calculations. The invention further enables the systematic use of target type probability information in the calculation of strobe track crosses and their associated quality which is particularly useful for deghosting purposes. Methods for utilisation of target type probability information in the processes of strobe tracking, association, track quality evaluation and multiple hypothesis tracking are also disclosed.

Abstract: There is provided a rocket trajectory estimating method comprising the steps of: measuring a GLOS angle of a flying rocket a tracking system; passing the GLOS angle data through a batch filter to reduce noises; estimating a rocket trajectory on the basis of the GLOS angle data, the noises of which have been reduced; passing the resulting rocket trajectory data through a Kalman filter to reduce biases; and estimating the rocket trajectory again on the basis of the corrected GLOS angle data and the positional information of the tracking system. Thus, there is provide a rocket trajectory estimating method capable of reducing observation errors (noises and biases) of a tracking system of a passive ranging system, which does not have need of any laser range finders, to enhance the accuracy of rocket trajectory estimation.

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: An apparatus and method for measuring coefficients of retroreflectance of retroreflective surfaces such as road signs involves use of a modified light based range finder. The apparatus includes a power attenuation factor data base which relates pulse width of received pulses to power attenuation of the transmitted pulses. The range finder calculates target range based on time of flight of light pulses. The apparatus automatically calculates the absolute coefficient of retroreflectance for an unknown reflective surface being measured by comparison of the measurement to a reading with the same instrument of a known reflectance standard.

Abstract: In an air traffic control radar system, a processor is described for correlating primary target data received from a target with a target report and a target track, wherein the processor has a search acquisition time that is adapted to the distance of the target from the radar site. The search acquisition time is shorter for more distant targets. The processor can employ a shorter cycle time (time quantum) to establish a correlation between target data and target reports than would otherwise be possible with conventional fixed search acquisition times. The average total dwell time may be reduced while complying with the mandated maximum processing time for more difficult radar reports.

Abstract: A pseudo-noise-modulated spread spectrum is irradiated undirectedly--or, encoded by different modulation, into mutually displaced spatial sectors--and the energy (20) received after reflection at a potential target (13) is cross-correlated, using the pseudo-noise code which is predetermined at the transmission end, in order to provide a spherical monitoring effect which is continuous but which cannot be located in respect of its origin, to provide a warning in particular for marine craft, land vehicles and aircraft against an attacking guided missile as the target (13) to be repelled, and in order to be able to transfer to a target tracker (12) distance and speed information obtained from the correlation product, with the alarm signal, if the alarm sensor (11) is not itself also used as the tracking sensor.

Abstract: A radar system is described for use in vehicular applications. The radar system is particularly suited to backup warning systems and side-object warning systems. The radar minimies many of the problems found in the prior art by providing programmable delays and programmable gain. The radar uses a range search algorithm to detect and sort targets at various ranges within the field of view of the radar. Each target range corresponds to a particular delay and gain setting. The radar searches for targets at the various ranges by running a target search algorithm. For each target range, the search algorithm causes the proper time delay and gain setting. Targets within the selected range are detected and catalogued. A display is used to warn the driver of the vehicle of the presence of targets at the various ranges. The warning may be visual and/or audible.

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: An apparatus and method for accurately determining a target distance in adverse weather conditions utilizing both LASER and RADAR is disclosed. The radar signals are used to determine an approximate range which is then used as a gating window for the determination of which laser reflection is from the actual target as opposed to a reflection from the atmospheric interference. The method basically comprises the steps of initiating a radar pulse in the direction of a target and receiving a reflection, transmitting a laser signal and receiving a plurality of reflections, determining an approximate range based on the radar signals, and using this approximate range to ascertain which of the laser reflections is from the target. This determination is preferably made by generating a gating signal and gate width from the radar signals and passing the set of laser range signals through the gate to eliminate the false signals and select the signal that survives the gate as the accurate target range.

Abstract: The objectives of the invention are met by an improved radar tracking system and a process of radar tracking. In the improved system and process, an estimate of a target range and a range uncertainity swath from a first radar system is inputted into a second radar system along with a duty factor. The second radar system determines a set of zero eclipse intervals and respective ranges of range pulse repetition frequencies that solves a first set of equations. A usable range pulse repetition frequency is chosen from the results. Next, an estimated target Doppler frequency region and a Doppler uncertainity swath is inputted into the second radar system. The second radar system is instructed to determine a set of clear Doppler frequency region intervals, and respective ranges of Doppler frequency pulse repetition frequencies by solving a second set of equations.

Abstract: An apparatus and method for measuring coefficients of retroreflectance of retroreflective surfaces such as road signs involves use of a modified light based range finder. The apparatus includes a power attenuation factor data base which relates pulse width of received pulses to power attenuation of the transmitted pulses. The range finder calculates target range based on time of flight of light pulses. The apparatus automatically calculates the absolute coefficient of retroreflectance for an unknown reflective surface being measured by comparison of the measurement to a reading with the same instrument of a known reflectance standard.

Abstract: A system and method of processing data in a sensor system which receives signal returns from pulsed coherent transmitted signals which are transmitted at a pulse repetition rate and with a pulse repetition interval (PRI). The method includes providing range-filtered data in response to the received signal returns; formatting successive sets of data received during a post detection integration (PDI) interval into a plurality of overlapping coherent processing interval (CPI) data sequences; performing FFT processing on the overlapping CPI data sequences to provide transformed data sequences; performing range-sample CPI processing on the transformed data sequences; and performing noncoherent integration (NCI) processing on output data from the range-sample CPI processed data sequences over a range trajectory in accordance with hypothesized radar-target range rate to provide noncoherent gain-enhanced output data.

Abstract: An apparatus and computer-implemented method of determining a probability that a first track and a second track represent the same physical object.

Abstract: A method for detecting and tracking turns of a maneuvering target comprises the steps of determining first and second radar information of the maneuvering target. The first and second radar information and a set of target speeds are used to determine a set of turn radii for the maneuvering target. The first and second radar information and a set of target arc speeds are used to determine a second set of turn radii for the maneuvering target. The set of turn radii and the set of target speeds define a speed-radius curve, and the second set of turn radii and the set of target arc speeds define an arc speed-radius curve. An intersection of the speed-radius and arc speed-radius curves is located, and the intersection is used to determine whether the maneuvering target has made a turn.

Abstract: A bistatic coherent unlocked radar system and processing method using an advanced waveform that permits bistatic unlocked coherent operation of an unlocked radar transmitter and receiver. The waveform implements intrapulse fine range resolution, pulse to pulse coherency and burst to burst frequency agility to provide for enhanced target detection and robust operation in electronic countermeasure environments. A continuous sequence of pulses at different frequencies is transmitted that may contain an acquisition frequency that is revisited) more times than the other frequencies. Energy reflected from a target is processed to detect energy at the acquisition frequency, for example, over a plurality of range bins and predetermined pulse repetition intervals. A range pattern is generated if the detected energy is above a predetermined threshold. The energy is centroided to indicate the relative angle to the target. The transmitted frequencies contained in the pattern of energy are identified.

Abstract: A radar system for processing a series of radar returns to determine Doppler velocity of an object. Each one of the radar returns is produced in response the object reflecting each one of a series of transmitted radar pulses. The series of radar returns is processed in a sequence of successive dwells. Each one of the dwells has a predetermined number of radar returns. The radar system includes a system clock for producing a series of clock pulses. A range gate is provided for sampling each one of a series of radar returns produced in response to a each one of a series of transmitted radar pulse. The range gate has a time duration equal to an integer number of, N, clock pulse periods. A range gate positioning system initiates the range gate a selected time, .DELTA., after each one of the transmitted pulses. The positioning system determines the selected time, .DELTA.

Abstract: A cost-effective ultra-wideband 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 radar pulses e.g. at a plurality of frequencies in a range of about 2 MHz to about 10 GHz 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 of the receiver 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: A cell averaging (CA) constant false alarm rate (CFAR) device for use in a radar system which filters noise and clutter from a signal containing a plurality of range cells. A moving window average calculator (MWAC) calculates a moving window average (MWA) for each range cell in a signal. A central processing unit (CPU) estimates a skew factor of a probability density function (PDF) and calculates an offset factor based on information contained in the signal. A multiplying device multiplies the offset factor by the MWA calculated for each range cell and creates a second signal containing a plurality of range cells. A comparator compares each range cell of the second signal to each corresponding range cell of the original signal, selects a the larger value of the two signals, and creates a third signal which is essentially free of noise and clutter.

Abstract: An apparatus and method for accurately determining a target distance in adverse weather conditions utilizing both LASER and RADAR is disclosed. The radar signals are used to determine an approximate range which is then used as a gating window for the determination of which laser reflection is from the actual target as opposed to a reflection from the atmospheric interference. The method basically comprises the steps of initiating a radar pulse in the direction of a target and receiving a reflection, transmitting a laser signal and receiving a plurality of reflections, determining an approximate range based on the radar signals, and using this approximate range to ascertain which of the laser reflections is from the target. This determination is preferably made by generating a gating signal and gate width from the radar signals and passing the set of laser range signals through the gate to eliminate the false signals and select the signal that survives the gate as the accurate target range.

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 range finder and hidden object locator is based on ultra-wide band radar with a high resolution swept range gate. The device generates an equivalent time amplitude scan with a typical range of 4 inches to 20 feet, and an analog range resolution as limited by a jitter of on the order of 0.01 inches. A differential sampling receiver is employed to effectively eliminate ringing and other aberrations induced in the receiver by the near proximity of the transmit antenna, so a background subtraction is not needed, simplifying the circuitry while improving performance. Uses of the invention include a replacement of ultrasound devices for fluid level sensing, automotive radar, such as cruise control and parking assistance, hidden object location, such as stud and rebar finding. Also, this technology can be used when positioned over a highway lane to collect vehicle count and speed data for traffic control.