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空时自适应处理 ward报告

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【实例简介】
林肯实验室发表的技术报告,有关机载雷达空时自适应处理的,希望对大家有帮助。
MASSACHUSETTS INSTITUTE OF TECHNOLOGY LINCOLN LABORATORY SPACE-TIME ADAPTIVE PROCESSING FORAIRBORNE RADAR WARD Group 102 Accesion Fc NTIs CRA&3 TECHNICAL REPORT 1015 DTIC TAB Justification Distribution/ Availability Codes I 3 DECEMBER 1994 Avail and oi Dist Special A-1 pproved for publie release; distribution is unlimited LEXINGTON MASSACHUSETTS AbSTrACT Future airborne radars will be required to detect targets in an interference background comprised of clutter anld jamming. Space-time adaptive processing (STAP)refers to multidimensional adaptive filtering algorithms that simultaneously combine the signals from the elements of an array antenna and the multiple pulses of a coherent radar waveform, to suppress interference and provide target detec tion. STAP can improve detection of low-velocity targets obscured by mainlobe clutter, detection of targets masked by sidelobe clutter, and detection in combined clutter and jamming environments. This report analyzes a variety of approaches to STaP problem. Optimum, or fully adaptive processing is reviewed. Computa tional complexity and the need to estimate the interference from a limited amount of available data make fully adaptive STAP impractical. As a result, partially adap tive space-time processors are required. A taxonomy of reduced-dimension STAP algorithms is presented where algorithms are classified based on the type of pre processor employed. For example, beamspace algorithms use spatial preprocessing while post-doppler approaches perform temporal( doppler)filtering before adaptive processing. In some cases, the special structure of the clutter can be exploited to design preprocessors yielding minimum clutter rank. For each class, either sample matrix-inversion(SMI)or subspace-based weight computation may be employed. Simulation results are presented to illustrate various performance metrics, includ ing SNR, adapted patterns, minimum detectable velocity, and required degrees of fr eedom A CKNOWLEDGMENTS This report has been influenced by many people within Lincoln Laboratory I would like to thank Ken Senne for the technical guidance and encouragement he has given me throughout this work. Special thanks go also to Dave Martinez for providing me with time, support, and motivation to complete this report Much of my education in the area of space-time adaptive processing is a di- rect result of many enlightening discussions with Allan Steinhardt, Steve Krich, Ed Baranoski. Steve Smith, Ken Teitelbaum, and Dan Marshall. Their contributions are gratefully acknowledged. Early encouragement from Allan Steinhardt and Steve Krich was particularly appreciated. My thanks go again to Allan and ed for their careful reviews of the draft; their comments have greatly improved the presenta tion.Professor Richard Bucy of the University of Southern California also provided helpful comments on portions of this report. Finally, i would like to acknowledge the continued sponsorship of CAPT. ryan Henry of the advanced Research Projects Agency. Also, I thank Jim Hall of the Offce of Naval Research, Nancy MacMeekin of Naval Air Warfare Center, and CAPT. Dale Babin of Naval Air Systems Command for their continued interest in the area of space-time adaptive processing technology. Their support over the last two years is gratefully acknowledged TABLE OF CONTENTS abstract Acknowledgments List ofⅢ lustrations List of Tables 1. INTRODUCTION 2. AIRBORNE ARRAY RADAR SIGNAL ENVIRONMENT 2.1 Introduction 2.2 Radar System Description 7 2.3 Target 12 2.4 Noise 2.5 Jamming 18 2.6 Clutter 20 2.7 Range -Doppler View of the Interference 2.8 Summary 51 3. SPACE-TIME PROCESSING FUNDAMENTALS 53 3.1 Introduction 53 3.2 General Architecture and Assumptions 3.3 Fully Adaptive STAP 57 3.4 STAP Performance Metrics and Fully adaptive Performance 59 3.5 Sample Support and Smi 3.6 Computational Complexity 4. PARTIALLY ADAPTIVE STAP 81 4.1 Introduction 81 4.2 A Generic Architecture 81 4.3 Exploiting Low- Rank Interference 4.4 Application tO STAP 88 5. ELEMENT-SPACE STAP 95 5.1 Introduction 95 5.2 Element-Space Pre- Doppler STAP 95 5.3 Element-Space Post-Doppler TABLE OF CONTENTS (Continued 6. BEAMSPACE STAP 135 6.1 Introduction 135 6.2 Beamspace Pre-Doppler STAP 136 6.3 Beam-Space Post-Doppler STaP 153 7. ADDITIONAL PERFORMANCE RESULTS 169 8. SUMMARY AND FUTURE WORK 185 APPENDIX A-PROOF OF BRENNANS RULE 187 APPENDIX B- PROOF OF THEOREM 2 191 APPENDIX C- DISPLACED PHASE CENTER ANTENNA (DPCA) PROCESSING 195 REFERENCES 20 LIST OF ILLUSTRATIONS Fig age ace-time adaptive processing. (a) The power spectral density of the in terference(clutter and jamming) seen by an airborne radar(b) Example adapted response 3 (a) Platform geometry.(b )Top view. Processing for each array element channel. 10 4 The radar CPi datacube A ring of ground clutter for a fixed range 21 The B=1 clutter ridge. The PRF is 300 IIz.(a) Doppler frequency vS. sin p.(b) Normalized Doppler vS, spatial frequenc Clutter loci for different velocities.(a) Stationary platform, va =0.(b Doppler unambiguous, A = 0.5.(c) Doppler ambiguous, B= 1.5.(d Doppler ambiguouS, 6=2.67 27 Effective array position for successive pulses of a CPI N=4,M=3,B=1 Clutter observations are repeated by different elements on different pulses The element pattern. A -30-dB backlobe level is assumed 32 Example scenario: received CNR per column as a function of azimuth. 35 11 Illustrating Brennan's rule: clutter eigenspectra for the example radar sys tem with different platform velocities. 35 12 array geometry with velocity misalignment 13 Example clutter ridges with velocity misalignment,forβ=1.(a)φa=0° (b)φa=10°.(c)pa=45°.(d)φa=90 Example clutter ridges with velocity misalignment, for Doppler-ambiguous clutter:.(a)=26,oa=10°.(b)6=2.67,中a=60° 41 Clutter eigenspectra for different misalignment angles Clutter eigenspectra with misalignment for different backlobe levels 43 17 Clutter eigenspectra for different levels of iCm 47 8 Range-Doppler view of interference, for the case of a low -PRF waveform The clutter is ambiguous in Doppler and unambiguous in rango 50 ⅸx LIST OF ILLUSTRATIONS Continued figure Page Range-Doppler view of interference, for a high-PRF waveform. The clutter is unambiguous in Doppler but ambiguous in range 50 20 A general block diagram for a spacc-time processor 4 21 Data-domain view of space-time adaptive processing 55 Fully adaptive space-time processing 23 Example scenario: optimum fully adaptive STAP. (a)Adapted pattern.(b Principal cuts at target azimuth and Doppler 63 24 Example scenario: tapered fully adaptive STAP. (a) Adapted pattern.(b) Principal plane cuts at target azimuth and Doppler 25 SINR for the optimum and tapered fully adaptive STAPs 68 26 SINR for the optimum and tapered fully adaptive STAPs, including Doppler straddling losses 69 27 SINR loss for the fully adaptive stap 28 SINR improvement factor for the optiMum and tapered fully adaptive STAP. 29 Expected SINR loss for SMI with matched steering vector 79 30 A generic partially adaptive STAP architecturc 82 31(a)Reduced dimension adaptive processing with low-rank interference. (b) Whitening filter viewpoint 86 32 Another block diagram for reduced-dinenision space-time adaptive processing. 92 33 A taxonomy of reduced-dimension STAP algorithms, classified by the type of nonadaptive transformation applied to the CPI data 93 34 Element-space pre-Doppler STAP(a) Sub-CPI processing.(b) Full CPI pr rocessing 97 35 I=2 element-space pre -Doppler STAP.(a)Sub- CPI adapted patterN(b) Principal cuts in angle and Doppler 103 Sub-CPi weight vector decomposed into spatial beamformer components, illustrating the DPCA effect 106 LIST OF ILLUSTRATIONS (Continued) figure P age Composite pattern for Doppler bin 5.(a) Full pattern(b) Principal cuts in angle and Doppler 107 38 SINR loss for element space pre-Doppler. Zero intrinsic clutter motion 109 Block diagram of post-Doppler adaptive beamforming(factored post- Doppler). 112 Example performance for Doppler bin 6(100 Hz) with 40-dB Chebyshev Doppler filters.(a) Clutter power spectral density.(b )Adapted pattern Example performance for Doppler bin 6(100 Hz) with 80-dB Chebyshev Doppler filters.(a) Clutter power spectral density.(b) Adapted pattern 115 42 SINR loss as a function of Doppler filter sidelobe level 117 Block diagram for multiwindow post-Doppler STAP 120 44 Multiwindow post-Doppler form of Brennans rule. Example for N=4, M 3, K=2, and 6= 1. The grouping of pulses for the two filters satisfies Theorem 3 124 45 Block diagram for PRI-staggered post-Doppler STAP 126 46 Block diagram for adjacent-bin post-Doppler Stap 127 Clutter eigenspectra for multiwindow post-Doppler approaches with K 2.(a)PRI-staggered post-Doppler, covariance matrix for Doppler bin 0 (b) PRI-staggered post-Doppler, Doppler bin 3.(c)PRI-staggered post Adjacent-bin, Doppler bin 3.(f) Adjacent-bin, Doppler bin o er bin 0.(e) Doppler, Doppler bin 9.(d)adjacent-bin post-Doppler, Doppler bin 0(e 129 48 SINR loss performance for PRI-staggered and adjacent-bin post-Doppler STAP.(a) Untapered(uniform)Doppler filters(b)30-dB Chebyshev Doppler filters.(c60-dB Chebyshev Doppler filters. (d)90-dB Chebyshev Doppler filters 133 49 Beamspace pre-Doppler STAP(a) Sub-CPI processing. (b) Full CPI processing. 137 50 Beamspa.ce version of Brennan's rule for the case N=4, Kt=3, Ks=2 and b=1 142 【实例截图】
【核心代码】

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