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Radar Signal Parameter Estimation And Image Processing Of High-speed Maneuvering Target

Posted on:2010-07-31Degree:DoctorType:Dissertation
Country:ChinaCandidate:W C LiFull Text:PDF
GTID:1118360278956562Subject:Information and Communication Engineering
Abstract/Summary:PDF Full Text Request
Along with the unceasing development of domestic and foreign missile defense penetration and counter-defense penetration technology, the high-speed maneuver has become the main means of defense penetration. The high-speed maneuvering target is provided with a big radar radial velocity and acceleration, if the conventional signal processing method is used, the resolution performance and signal noise ratio of defense radar decrease, and the wideband range profile is broadening, and the two-dimension image is blurring, which induce that the defense radar fail in detection, tracking and image formation for the high-speed maneuvering target. How to enhance the radar in target detection, tracking and image formation for the high-speed maneuvering target already became the front topic and the pressing task for the current radar technology domain.This dissertation takes the ballistic missile defense as the research background, focuses on radar signal parameter estimation and image processing of the high-speed maneuvering target,and systematically studies the radar signal model, and the related processing method of the high-speed maneuvering target, including frequency modulation (FM) parameters estimation of multi-component LFM signals, the resolution of multi-component LFM signals based on quadratically matched processing, motion compensation of wideband range profile, two-dimension imaging and cross-range calibration. The research results mainly involve:1) The high-speed maneuvering target's echo characteristics of both conventional narrow band radar and wide band imaging radar are extracted. In order to improve the radar exploration performance of the high-speed maneuvering target, the target's motion characteristics and echo signal model, and the radar signal processing and compensating methods should be studied. Firstly, the radial velocity and acceleration influence brought by the high-speed maneuver are analyzed. Then the echo signal models of narrow-band radar and wideband imaging radar are extracted, and the limitations of conventional processing method are analyzed. Spectral expansion coefficient is proposed to measure spectral expansion, and range measuring and spectral expansion effects caused by movement parameter are analyzed quantificational. Finally, in order to select the optimal FM parameters estimation method, the time-frequency distribution and the ambiguity chart characteristic have been analyzed for the multi-component LFM signals.2) The FM parameters estimated methods of the multi-component LFM signals have been studied. The radar echo processing of the high-speed maneuvering target is related with detection and parameter estimation of the LFM signals. In order to study the quadratically matched processing and parameter estimation of the LFM signals, the reciprocal transforming relationship of FM parameters estimated methods for the continuous complex LFM signals, including Radon-Wigner transform (RWT), Wigner-Hough transform (WHT), Fractional Fourier transform (FrFT), Dechirp,Chirp-Fourier transform (CFT) and Maximum Likelihood (ML), are studied in theory for the first time, and the optimal expression of FM parameters estimation is proposed. Secondly, Multi-resolution fast parameters estimation arithmetic of LFM signals via RWT is offered. The parameters estimation performance is studied on frequency deviation coefficient and residual expansion coefficient, and the computational cost is analyzed. Finally, the fast algorithm of Radon-Ambiguity transform (RAT) method of the discrete signals is proposed. Simulation results have validated that both RWT and RAT can reach the Cramer-Rao bound (CRB) even on low SNR. The analysis indicates that RWT accesses RAT in computational cost. The RWT method can estimate the frequency and chirp rate of the LFM signals, and adapt to analyze arbitrary the multi-component LFM signals. The RAT method fits to estimate the chirp rate of the multi-component LFM signals in the same chirp rate, because the total energy of various component signals can be utilized.3) Based on RWT method, the resolutions of multi-component LFM signals and multi-target are studied respectively. The RWT output approximate expression is given based on quadratic Taylor's series expansion for the first time, and the joint resolution mathematical expression of the FM parameters, and the joint resolution of delay time, frequency and chirp rate are offered in theory, which are validated by simulation results. Then, the joint resolution expression of velocity and acceleration of the pulse Doppler radar is offered. It is indicated that the motion parameters can be distinguished if the radial distance deviation reaches half wave length. The simulation results have been given to compare the performance of the Fourier transform and the RWT method. Finally, the joint resolution of distance, velocity and acceleration for LFM radar is studied, which indicated that the joint resolution condition is decided by the radial position deviation (resolution cell level) and the radial distance moving deviation in coherent time (wave length level) of the two targets. The simulation results have been given to compare the performance of the matched filtering and the RWT method. This research is helpful to track maneuvering target, as well as group target resolution and recognition.4) The motion compensation, continuous tracking, ISAR imaging and cross-range calibration of the wideband radar for the high-speed maneuvering target are studied systemically. Based on the spectral expansion characteristics of the velocity and acceleration, a novel linear model of wideband range profile of maneuvering target is proposed. Linear parameter estimation and compensation of range profile via RAT are presented, and the measurement errors of range and velocity are analyzed. The simulation results show that this method can resolve the range profile spectral expansion of maneuvering target unknown motion parameters. In order to use radar resource effectively, once the target has been tracked by narrow band signal, the radar can switch to mono-pulse tracking and imaging of wideband signal. Angle, distance and velocity measurement models of wideband range profile are presented, which are validated by simulation results. Target orientation and tracking based on range profile can increase data rate of target tracking, which can enhance the tracking capability of maneuvering target.The scaled RWT imaging and cross-range scaling method is proposed for the rotating target with stable acceleration. Firstly, the rotating parameters are calculated via weighted least square method after obtaining the FM parameters of signals on multi-range. The slow time signals are compensated using rotating parameters. Then, the ISAR imaging of scaled RWT methods is implemented with cross-range calibration. The calculation speed of this algorithm is improved in great part compared to general RWT imaging, and imaging performance is steady-going. The simulation results and ISAR imaging processing of radar data in outfield validate the method. The method presents good application foreground to the ISAR imaging and calibration of uncooperative motive targets. When target uniform motion, the longitudinal parameter compensation method still have a very good application value.In order to validate scaled RWT imaging method, the ISAR data generating technology of maneuvering target is presented via interpolation sampling based on outfield experimental radar data, and the method is validated by simulation results. Finally, based on the orthogonal relation between the centerline and the line through axially symmetric points in the symmetrical target, a novel method of rotation angle estimation and cross-range calibration is definitely proposed for the symmetrical target. The estimation error expression of the scaling parameter is offered, which is validated by simulation results, and influencing factors of the parameter estimation error is analyzed quantitatively. This method is very simple in structure and have low computation cost.The research results can be applied to pulse Doppler radar, LFM continuous-wave radar, step frequency radar, long-rang early-warning radar and imaging radar, and offer references for many fields such as radar signal processing, and have a great theory significance and military value for the application domain study such as the ballistic missile survival and defense penetration ability.
Keywords/Search Tags:High-speed maneuvering target, LFM signals, Frequency modulation (FM) parameter estimation, Radon-Wigner transform, Radon-Ambiguity transform, Joint resolution of range,velocity and acceleration, Range profile, Motion compensation, ISAR imaging
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