Showing papers on "Moving target indication published in 2004"

Multiple-input multiple-output (MIMO) radar: performance issues

Abstract: The application of multiple-input multiple-output (MIMO) techniques to multistage radar offers a number of advantages, including improved resolution and sensitivity. Depending upon the radar's mode of operation, the array design and the environment, these advantages may or may not be significant. In this paper, a simple analytic model for ground moving target indicator (GMTI) radar detection is presented and its predictions are compared with simulation. Conventional single-input multiple output (SIMO) and MIMO GMTI radars are compared in terms of minimum detectable velocity, area-search rates and array sidelobes. Optimal waveform cross-correlation matrices are identified for MIMO radars, given different performance criteria. Finally, bounds are developed for MIMO arrays with uniformly sampled virtual apertures.

Statistical analysis of multilook SAR interferograms for CFAR detection of ground moving targets

Abstract: This paper examines the statistics of the phase and magnitude of multilook synthetic aperture radar (SAR) interferograms toward deployment of along-track interferometry (ATI) for slow ground moving-target indication (GMTI). While the known probability density function (pdf) of the interferogram's phase (derived under the assumption of Gaussian backscatter) is shown to agree almost perfectly for a wide variety of backscatter conditions, the corresponding magnitude's pdf tends to deviate strongly in most cases. Motivated by this discrepancy, a novel distribution is derived for the interferogram's magnitude. This pdf, called the polynomial or p-distribution, matches the real data much more accurately, particularly for heterogeneous composite terrain. For extremely heterogeneous terrain, such as urban areas, both pdfs for interferometric phase and magnitude fail and are extended. Based on these statistics, a completely automatic detection scheme with constant false-alarm rates (CFARs) for slow moving targets is proposed. All involved parameters required to determine the detection thresholds are estimated from the sample data. It is demonstrated, on the basis of experimental airborne SAR data, that this detector is capable of detecting slow moving vehicles within severe ground clutter.

Multiple phase center feedhorn for reflector antenna

Abstract: A feedhorn driving method and apparatus allows the establishment of multiple phase centers using only a single multimode feedhorn. At least two higher-order modes are extracted from the feedhorn and weighted in amplitude and phase. The phase center separation is established in accordance with an assigned weights. The feedhorn has application in i.a. moving target indication systems.

New assignment-based data association for tracking move-stop-move targets

Abstract: We present a new assignment-based algorithm for data association in tracking ground targets employing evasive move-stop-move maneuvers using ground moving target indicator (GMTI) reports obtained from an airborne sensor. To avoid detection by the GMTI sensor, the targets deliberately stop for some time before moving again. The sensor does not detect a target when the latter's radial velocity (along the line-of-sight from the sensor) falls below a certain minimum detectable velocity (MDV). Even in the absence of move-stop-move maneuvers, the detection has a less-than-unity probability (P/sub D/<1) due to obscuration and thresholding. Then, it is of interest, when a target is not detected, to develop a systematic technique that can distinguish between lack of detection due to P/sub D/<1 and lack of detection due to a stop (or a near stop). Previously, this problem was solved using a variable structure interacting multiple model (VS-IMM) estimator with a stopped target model (VS-IMM-ST) without explicitly addressing data association. We develop a novel "two-dummy" assignment approach for move-stop-move targets that considers both the problem of data association as well as filtering. Typically, in assignment-based data association a "dummy" measurement is used to denote the nondetection event. The use of the standard single-dummy assignment, which does not handle move-stop-move motion explicitly, can result in broken tracks. The new algorithm proposed here handles the evasive move-stop-move motion by introducing a second dummy measurement to represent nondetection due to the MDV. We also present a likelihood-ratio-based track deletion scheme for move-stop-move targets. Using this two-dummy data association algorithm, the track corresponding to a move-stop-move target is kept "alive' during missed detections both due to MDV and due to P/sub D/<1. In addition, one can obtain reductions in both rms estimation errors as well as the total number of track breakages.

Performance assessment of along-track interferometry for detecting ground moving targets

Abstract: Along-track interferometry (ATI) is an interferometric synthetic aperture radar technique that can be used to measure Earth-surface velocities. As such, the ATI technique holds promise for the detection of slowly moving ground targets. However, the models often used to characterize ATI performance were developed mainly in the context of mapping ocean currents, and they do not necessarily apply to the case of discrete, moving ground targets amidst clutter. We provide expressions for more accurately modeling the behavior of an ATI system in the context of ground moving target indication. Analysis and design equations are given for topics including target defocus, signal-to-noise and signal-to-clutter ratios, interferometric correlation, interferometric phase bias, target detection, geolocation accuracy, and area coverage rate.

Ten Methods to Fuse GMTI and HRRR Measurements for Joint Tracking and Identification

Abstract: : Mutual-aided target tracking and identification (ID) schemes are described by exploiting the couplings between the target tracking and object ID systems, which are typically implemented separately. A hybrid state space approach is formulated to deal with continuous-valued kinematics, discrete-valued target type and discrete-valued target pose (inherently continuous but quantized). We identify ten possible mutual aiding mechanisms with different complexity in different levels. The coupled tracker design is illustrated within the context of using ground moving target indicator (GMTI) and high-range resolution radar (HRRR) measurements as well as digital terrain elevation data (DTED) and road maps. The resulting coupled tracking and ID system is expected to outperform the separately designed systems particularly during target maneuvers, for recovering from temporary data dropout, and in a dense target environment. We simulate HRRR ID support information to assist in pose-model selection of an Interacting Multiple Model (IMM) tracker using GMTI measurements.

Three-dimensional SAR imaging of a ground moving target using the InISAR technique

Abstract: In this paper, a three-dimensional (3-D) interferometric synthetic aperture radar (ISAR) imaging method for moving targets is presented. This imaging method is based on the ISAR principle and the simple observation that all scatterers on a moving target move in tandem. The angular motion parameters in the cross-range directions could be estimated using the overall range profile of the moving target. Registration of the respective complex images at the two (or more) interferometric antennas can then be achieved via compensating the respective echoes at the raw data level, thus avoiding phase-unwrapping processing and image-resampling processing as required by conventional methods. Finally, a 3-D image of the moving target can then be reconstructed from the 3-D spatial coordinates of these scatterers. Furthermore, the method works well even for a target moving in heavily cluttered environments.

SAR-GMTI concept for RADARSAT-2

Abstract: RADARSAT-2 is a two-aperture SAR interferometer. When used for GMTI measurements, RADARSAT-2 uses beams in the 40° to 50° incidence angle range to maximise the radial velocity component of the vehicle motion. The airborne experimental SAR reported in this chapter is designed to replicate the RADARSAT-2 GMTI mode resolution and observation geometry and tests the data processing algorithms that can be migrated to the RADARSAT-2 GMTI processor. The greatest difference between the airborne and space-based SAR/GMTI capabilities arises from the relationship between the platform velocity and the along-track velocities of the moving targets. In the airborne case, the target speeds are a significant fraction of the radar speed and can reasonably estimate the azimuthal target speed.

An unscented particle filter for GMTI tracking

Abstract: Ground moving target indicator (GMTI) tracking is often carried out using extended Kalman filters, as in the variable-structure interacting multiple-model (VS-IMM) filter. In some scenarios, however, this is considered to be inadequate. It has been shown that in this case, a particle filter can give better performance. Such a filter, the variable-structure multiple-model particle filter (VS-MMPF), is given in the literature. In this paper we present a new approach to solving the GMTI tracking problem using a particle filter. We have developed an unscented particle filter, where the particles model the uncertainty over the motion model while, conditional upon the model, the target state is modelled using an unscented Kalman filter. Simulation results show that the UPF-based filter gives performance similar to the VS-MMPF with significantly fewer particles and better results than the standard VS-IMM approach.

Ground target tracking with STAP radar: selected tracking aspects

Abstract: Ground surveillance aims at near real-time production of a dynamic ground picture. This task comprises track extraction and track maintenance of single ground moving vehicles and convoys, mobile weapon systems or military equipment, as well as low-flying targets such as helicopters. For long-range, wide area, all-weather and all-day ground surveillance operating at high data update rates, GMTI radar proves to be the sensor system of choice (GMTI: ground moving target indication). By using airborne sensor platforms in stand-off ground surveillance applications the effect of topographical screening is alleviated, thus extending the sensor's field of view. In this chapter, selected tracking aspects are discussed. The following topics are of particular interest: Doppler blindness, road map information, and sensor data fusion.

Ground moving target tracking with road constraint

Abstract: The Tracking of a Ground Moving Target (GMTI) is a challenging problem given the environment complexity, the target maneuvers and the false alarm rate. Using the road network information in the tracking process is considered an asset mainly when the target movement is limited to the road. In this paper, we consider different approaches to incorporate the road information into the tracking process: Based on the assumption that the target is following the road network and using a classical estimation technique, the idea is to keep the state estimate on the road by using different "projections" approaches. The first approach is a deterministic one based either on the minimization of the distance between the estimate and its projection on the road or on the minimization of the distance between the measurement and its projection on the road. In this case, the state estimate is updated using the projected measurement. The second approach is a probabilistic one. Given the probability distributions of the measurement error and the state estimate, we propose to use this information in order to maximize the a posteriori measurement probability and the a posteriori estimate probability under the road constraints. This maximization is equivalent to a minimization of the Mahalanobis distance under the same constraints. To differentiate this approach from the deterministic one, we called the projection pseudo projection on the road segment. In this paper, we present a comparative study of the performances of these projection approaches for a simple tracking case. Then we extend the study to the case of road intersections in which we present a sequential ratio test in order to select the best road segment.© (2004) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Ground moving target detection for along-track interferometric SAR data

Abstract: This paper investigates different metrics for ground moving target indication (GMTI) with a multichannel synthetic aperture radar (SAR). These metrics are especially sensitive to targets that have an across-track component of velocity, v/sub y/, although they can also detect targets with an along track velocity component, v/sub x/. Not only are the metrics suitable for fully SAR compressed data, they are also meaningful when computed for range (pulse) compressed but Doppler uncompressed data (raw data). The use of both data domains allows for target detection over a larger v/sub y/ range than either used individually. For large v/sub y/, side-lobe suppression in fully SAR compressed data simultaneously suppresses the targets, giving an advantage to the raw data domain. For low v/sub y/, and especially with low RCS targets, the SAR compression gain facilitates detection, giving an advantage to the SAR compressed domain. By viewing the SAR compression as the application of a linear filter, the metrics are shown to be suitable for target detection after any linear filtering of the raw data, such as a linear time-frequency filter, or a simple transformation into the Doppler domain using an FFT filter. The metrics have in common that they are all based on the eigenvector decomposition of the sample covariance matrix. Their statistical properties are analytically compared and their detection capabilities are demonstrated on measured two-channel airborne SAR data in a variety of data domains. Some metrics are shown to allow target detection with low false alarm rates even in heterogeneous terrain, such as in urban areas, without compromising the probability of detection.

Utilizing negative information to track ground vehicles through move-stop-move cycles

Abstract: Ground vehicles can be effectively tracked using a moving target indicator (MTI) radar. However, vehicles whose velocity along the line-of-sight to the radar falls below the minimum detectable velocity (MDV) are not detected. One way targets avoid detection, therefore, is to execute a series of move-stop-move motion cycles. While a target can be acquired after beginning to move again, it may not be recognized as a target previously in track. Particularly for the case of high-value targets, it is imperative that a vehicle be continuously tracked. We present an algorithm for determining the probability that a target has stopped and an estimate of its stopped state (which could be passed to a tasker to schedule a spot synthetic aperature radar (SAR) measurement. We treat a non-detection event as evidence that can be used to update the target state probability density function (PDF). Updating the target state PDF using a non-detection event pushes the probability mass into regions of the state space in which the vehicle is either stopped or traveling at a speed such that the range-rate fails the MDV. The target state PDF updated with the non-detection events is then used to derive an estimate of the stopped target"s location. Updating the target state PDF using a non-detection event is, in general, non-trivial and approximations are required to evaluate the updated PDF. When implemented with a particle filter, however, the updating formula is simple to evaluate and still captures the subtleties of the problem.© (2004) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The moving object detection experiment on RADARSAT-2

Abstract: Under contract to the Canadian Space Agency and in cooperation with the Canadian Department of National Defence, MacDonald Dettwiler and Associates Ltd. will include an experimental ground moving target detection function in RADARSAT-2. The RADARSAT-2 design allows two portions of the full antenna aperture to be used independently with two separate receivers. This configuration provides a temporal (along-track) interferometer (ATI) capability. By appropriate processing of the received echo data from the two apertures, it is possible to detect targets that have a radial motion component and to measure their radial velocities. This element of the RADARSAT-2 spacecraft and ground system design is known as the moving object detection experiment (MODEX). Ongoing research into the properties of unscanned synthetic aperture radar (SAR) ground moving target indication (SAR GMTI) sensors of the RADARSAT-2 class has identified a number of features that are unique to SAR GMTI processing requirements. This paper desc...

Optimal cooperative placement of GMTI UAVs for ground target tracking

Abstract: With the recent advent of moderate-cost unmanned (or uninhabited) aerial vehicles (UAV) and their success in surveillance, it is natural to consider the cooperative management of groups of UAVs. The problem considered in this paper is the optimization of the information obtained by a group of UAVs carrying out surveillance of several ground targets distributed over a large area. The UAVs are assumed to be equipped with ground moving target indicator (GMTI) radars, which measure the locations of moving ground targets as well as their radial velocities. In this research, the Fisher information, obtained from the information form of Riccati equation, is used in the objective function. Sensor survival probability and target detection probability for each target-sensor pair are also included in the objective function. The optimal sensor placement problem is solved by a combination of deterministic as well as randomized optimization. Simulation results on two different scenarios are presented for four different types of prior information.

Signal and image processing in navigational systems

Abstract: Preface About the Author Introduction THEORY OF FLUCTUATING TARGET RETURN SIGNALS IN NAVIGATIONAL SYSTEMS Probability Distribution Density of the Amplitude and Phase of the Target Return Signal Two-Dimensional Probability Distribution Density of the Amplitude and Phase Probability Distribution Density of the Amplitude Probability Distribution Density of the Phase Probability Distribution Density Parameters of the Target Return Signal as a Function of the Distribution Law of the Amplitude and Phase of Elementary Signals Conclusions References Correlation Function of Target Return Signal Fluctuations Target Return Signal Fluctuations The Correlation Function and Power Spectral Density of the Target Return Signal The Correlation Function with the Searching Signal of Arbitrary Shape The Correlation Function under Scanning of the Three-Dimensional (Space) Target The Correlation Function in Angle Scanning of the Two-Dimensional (Surface) Target The Correlation Function under Vertical Scanning of the Two-Dimensional (Surface) Target Conclusions References Fluctuations Under Scanning of the Three-Dimensional (Space) Target with the Moving Radar Slow and Rapid Fluctuations The Doppler Fluctuations of a High-Deflected Radar Antenna The Doppler Fluctuations in the Arbitrarily Deflected Radar Antenna The Total Power Spectral Density with the Pulsed Searching Signal Conclusions References Fluctuations Under Scanning of the Two-Dimensional (Surface) Target by the Moving Radar General Statements The Continuous Searching Nonmodulated Signal The Pulsed Searching Signal with Stationary Radar The Pulsed Searching Signal with the Moving Radar: The Aspect Angle Correlation Function The Pulsed Searching Signal with the Moving Radar: The Azimuth Correlation Function The Pulsed Searching Signal with the Moving Radar: The Total Correlation Function and Power Spectral Density of the Target Return Signal Fluctuations Short-Range Area of the Radar Antenna Vertical Scanning of the Two-Dimensional (Surface) Target Determination of the Power Spectral Density Conclusions References Fluctuations Caused by Radar Antenna Scanning General Statements Line Scanning Conical Scanning Conical Scanning with Simultaneous Rotation of Polarization Plane Conclusions References Fluctuations Caused by the Moving Radar with Simultaneous Radar Antenna Scanning General Statements The Moving Radar with Simultaneous Radar Antenna Line Scanning The Moving Radar with Simultaneous Radar Antenna Conical Scanning Conclusions References Fluctuations Caused by Scatterers Moving Under the Stimulus of the Wind Deterministic Displacements of Scatterers under the Stimulus of the Layered Wind Scatterers Moving Chaotically (Displacement and Rotation) Simultaneous Deterministic and Chaotic Motion of Scatterers Conclusions References Fluctuations Under Scanning of the Two-Dimensional (Surface) Target with the Continuous Frequency-Modulated Signal General Statements The Linear Frequency-Modulated Searching Signal The Asymmetric Saw-Tooth Frequency-Modulated Searching Signal The Symmetric Saw-Tooth Frequency-Modulated Searching Signal The Harmonic Frequency-Modulated Searching Signal Phase Characteristics of the Transformed Target Return Signal under Harmonic Frequency Modulation Conclusions References Fluctuations Under Scanning of the Three-Dimensional (Space) Target by the Continuous Signal with a Frequency that Varies with Time General Statements The Nontransformed Target Return Signal The Transformed Target Return Signal Conclusions References Fluctuations Caused by Variations in Frequency from Pulse to Pulse Three-Dimensional (Space) Target Scanning Two-Dimensional (Surface) Target Scanning Conclusions References GENERALIZED APPROACH TO SPACE-TIME SIGNAL AND IMAGE PROCESSING IN NAVIGATIONAL SYSTEMS Foundations of the Generalized Approach to Signal Processing in Noise Basic Concepts Criticism Initial Premises Likelihood Ratio The Engineering Interpretation Generalized Detector Conclusions References Theory of Space-Time Signal and Image Processing in Navigational Systems Basic Concepts of Navigational System Functioning Basics of the Generalized Approach to Signal and Image Processing in Time Basics of the Generalized Approach to Space-Time Signal and Image Processing Space-Time Signal Processing and Pattern Recognition Based on the Generalized Approach to Signal Processing Peculiarities of Optical Signal Formation Peculiarities of the Formation of the Earth's Surface Radar Image Foundations of Digital Image Processing Conclusions References Implementation Methods of the Generalized Approach to Space-Time Signal and Image Processing in Navigational Systems Synthesis of Quasioptimal Space-Time Signal and Image Processing Algorithms Based on the Generalized Approach to Signal Processing The Quasioptimal Generalized Image Processing Algorithm The Classical Generalized Image Processing Algorithm The Difference Generalized Image Processing Algorithm The Generalized Phase Image Processing Algorithm The Generalized Image Processing Algorithm: Invariant Moments The Generalized Image Processing Algorithm: Amplitude Ranking The Generalized Image Processing Algorithm: Gradient Vector Sums The Generalized Image Processing Algorithm: Bipartite Functions The Hierarchical Generalized Image Processing Algorithm The Generalized Image Processing Algorithm: The Use of the Most Informative Area The Generalized Image Processing Algorithm: Coding of Images The Multichannel Generalized Image Processing Algorithm Conclusions References Object Image Preprocessing Object Image Distortions Geometrical Transformations Detection of Boundary Edges Conclusions References Appendix I: Classification of Stochastic Processes Appendix II: The Power Spectral Density of the Target Return Signal with Arbitrary Velocity Vector Direction of the Moving Radar in Space and with the Presence of Roll and Pitch Angles Notation Index Index

Dynamic logic algorithm used for detecting slow-moving or concealed targets in synthetic aperture radar (SAR) images

Abstract: The present invention includes an application of a dynamic logic algorithm to detect slow moving targets. Show moving targets are going to be moving in the range from 0-5 mph. This could encompass troop movements and vehicles or convoys under rough terrain. The method can be defined as a seven step process of detecting slow moving targets using a synthetic aperture radar (SAR), said slow moving targets being objects of interest that are moving in the range from 0-5 mph, wherein this method is composed of the steps of receiving SAR signal history data having an SAR image; assuming a presence of slow moving target in a SAR image based-on range, cross-range position, and velocity; assuming a presence of clutter; assigning target and clutter models that are probability distribution functions (pdf) that are defined to account for every pixel in the SAR image, wherein the target is modeled using a sum of Gaussians fitted along the target shape model, while the clutter is modeled with a uniform distribution; computing a “target present” predetermined threshold value; converging the target model to a minimum variance value; and comparing the target model minimum variance value to the predetermined threshold to determine if a target is present or absent.

Modeling Intent for a Target Tracking and Identification Scenario

Abstract: The tracking goal is to reduce positional uncertainty. There are many ways to reduce tracking uncertainty: including classification data, using trafficability maps, and employing behavior information. We seek to extend tracking and identification modeling by incorporating intent to update prediction velocity vectors. A hybrid state space approach is formulated to deal with continuous-valued kinematics and discrete-valued target type, pose (inherently continuous but quantized), and intent behavior. The coupled tracker design is illustrated within the context of using ground moving target indicator (GMTI) and high range-resolution (HRRR) measurements as well as digital terrain elevation data (DTED), road map, and estimated goal states. The resulting Intent Coupled Tracking and Identification (ICTI) system is expected to outperform separately designed systems particularly during target maneuvers and recovering from temporary data dropout.

Technique for non-coherent integration of targets with ambiguous velocities

Abstract: A method for processing pulsed-Doppler radar signals to detect a target includes transmitting radar signals from a radar system according to a predetermined frequency technique including signals having frequency diversity, receiving signals within a frequency band, including a target return signal having a frequency indicative of the velocity of the target, and transforming the target return signal using a Fourier Transform having a variable frequency scale.

The Earth rotation effect on a LEO L-band GMTI SBR and mitigation strategies

Abstract: Space based radars (SBR) have been used to accomplish a number of civilian and military missions. Most recently, SBR concepts have been considered to perform ground moving target indication (GMTI) radar modes. Unlike airborne surveillance platforms, SBR clutter returns are affected by the high satellite velocity and Earth rotation. The phenomenology of the Earth's rotation, and its impact on clutter Doppler returns, are discussed for a Low Earth Orbit (LEO) L-band radar concept. The USA Air Force's Research Laboratory Space Time Adaptive Processing Tool (RLSTAP) high fidelity radar modeling tool is used to provide simulated data in order to demonstrate the Earth rotation effects, and resulting clutter rejection impact on slow moving target detection.

A digital beamforming processor for the joint DoD/NASA space based radar mission

Abstract: The space based radar (SBR) program includes a joint technology demonstration between NASA and the Air Force to design a low-earth orbiting, 2/spl times/50 m L-band (1.26 GHz) radar system for both Earth science and intelligence-related observations. A key subsystem aboard SBR is the electronically-steerable digital beamformer (DBF) network that interfaces between 32 smaller sub-antenna panels in the array and the on-board processing electronics for synthetic aperture radar (SAR) and moving target indication (MTI). In this paper, we describe the development of a field-programmable gate array (FPGA) based DBF processor for handling the algorithmically simple yet computationally intensive inner-product operations for wideband, coherent beamforming across the 50 m length of the array. Tests with an antenna array simulator demonstrate that the beamformer performance metrics (0.07/spl deg/ rms phase precision per channel, -39.0 dB peak sidelobe level) will meet the system-level requirements for SAR and MTI operating modes.

Technique for cancellation of elevated clutter for the detection of fixed and ground moving targets under trees

Abstract: A target is detected under a forest canopy or other elevated clutter where the target is obscured by the elevated clutter. Radar returns reflected from the target on the surface, combined with those from the elevated clutter are digitized. Motion compensation is performed for the radar returns with respect to the target to obtain a focused first synthetic aperture image of the target. Next, the radar returns are motion compensated with respect to the elevated clutter at various heights above the surface to obtain images of the elevated clutter. The elevated clutter within the images at the various heights above the surface is identified and coherently subtracted from the original synthetic aperture images.

A multichannel spaceborne radar for the COSMO-Skymed Satellite Constellation

Abstract: This work briefly describes a multibeam synthetic aperture radar (SAR) for COSMO-SkyMed of second generation, that can be obtained by limited modifications to the design of the original design (first generation). The new system is characterized by multiple transmitting and receiving channels, to achieve the largest possible baseline. This is required for MTI (moving target indicator) surveillance, sea surface monitoring by along-track interferometry, and moving targets relocation in high resolution SAR images. Moreover, a fully polarimetric SAR is obtained by using an active antenna with transmit/receive (T/R) modules designed to receive only one linear polarization at each interrogation.

Antenna auto-calibration and metrology approach for the AFRL/JPL space based radar

Abstract: The Air Force Research Laboratory (AFRL) and the Jet Propulsion Laboratory (JPL) are collaborating in the technology development for a space based radar (SBR) system that would feature a large aperture lightweight antenna for a joint mission later in this decade. This antenna system is a 50 m/spl times/2 m electronically steerable phased array in L-band (1260 MHz center frequency, 80 MHz bandwidth) and contains 384/spl times/12 transmit/receive modules. The radar is designed to operate in a variety of modes including synthetic aperture radar (SAR) and moving target indication (MTI). Stringent requirements are placed on phase center knowledge and antenna sidelobe levels during a data take, in the presence of temperature changes due to the orbital thermal environment, self heating, spacecraft platform vibrations, and mechanical deformation. We present an auto-calibration and metrology system concept to correct for phase errors and mechanical deformation during the mission.

2D rigid-body target modelling for tracking and identification with GMTI/HRR measurements

Abstract: Joint ground moving-target tracking identification is a crucial task in a modern combat operation Due to the entirely different environment, ground moving-target tracking is quite different from airborne target tracking A major difference lies in target modelling In airborne target tracking, a target is usually treated as a point, while for ground target tracking, a target is considered a rigid body Two approaches for 2D rigid-body target modelling are proposed Equipped with ground moving-target indicator and high-resolution range sensors, the new approaches effectively explore the concepts of local and global motions of a rigid body The kinematics of a global motion is described by a constant acceleration model, and a local motion is modelled by the pivoting centre and pseudocentre approaches The proposed models are implemented by the extended Kalman filter with and without a probabilistic data association filter The simulation results show that the proposed approaches not only correctly track a rigid-body target in a complicated scenario but also simultaneously report its structural information

Optimal cooperative placement of UAVs for Ground target tracking with Doppler radar

Abstract: With the recent advent of moderate-cost unmanned (or uninhabited) aerial vehicles (UAV) and their success in surveillance, it is natural to consider the cooperative management of groups of UAVs. The problem considered in this paper is the optimization of the information obtained by a group of UAVs carrying out surveillance of several ground targets distributed over a large area. The UAVs are assumed to be equipped with Ground Moving Target Indicator (GMTI) radars, which measure the locations of moving ground targets as well as their radial velocities (Doppler). In this research the Fisher information, obtained from the information form of Riccati equation, is used in the objective function. Sensor survival probability and target detection probability for each target-sensor pair are also included in the objective function, where the detection probability is a function of both range and range rate. The optimal sensor placement problem is solved by a genetic algorithm based optimizer. Simulation results on two different scenarios are presented for four different types of prior information.

Joint Doppler and polarization characterization of moving targets

Abstract: In through-the-wall imaging radar systems, the synthesized images may not provide sufficient range and cross-range resolution for visual classification and identification of the targets. Target movement and target Doppler characteristics can be used to combat resolution limitations and improve object discrimination. However, slowly moving targets and targets moving perpendicular to the incident waves render target motion ineffective in high-resolution imaging. We utilize the target's polarization properties and introduce time-varying polarization signature estimation based on polarization time-frequency distribution.