The Imaging Technology Of The Missile-borne SAR With Maneuvers

Applying SAR techniques to guidance weapon systems can effectively improve the guidance precision and the attack ability of the medium-long range missile. However, the missile-borne SAR, compared with traditional constant-velocity SAR, is faced with many complex problems induced by missile's maneuverable dynamics such as track-changing fight, lateral avoidance and vertical diving. The dissertation hence focuses on missile-borne SAR imaging issues under the maneuvering fight condition.First the current research status of missile-borne SAR system and technique is briefly introduced. Then aiming at the problem of missile-borne SAR imaging with maneuvers, the advantages and disadvantages of the modified time domain imaging method and subaperture based imaging method are analyzed. The former, easily combined with accurate motion compensation, can be extended and applied to SAR imaging with arbitrary track. But large computational complexity restricts its practical application. On the premise of meeting resolution requirement, the latter, imaging only with subaperture data, can decrease the difficulty of motion compensation and computational complexity. According to missile's possible motion modes during subaperture, the dissertation mainly studies the application of the second method in missile-borne SAR.Aiming at the problem of missile-borne SAR imaging with the uniform rectilinear dive trajectory, the effects of the missile's vertical velocity on SAR echo and imaging quality are analyzed through theoretical calculations and experiment simulations and the imaging method, directly using the missile's linear diving velocity, is put forward . The relationship between the actual lateral resolution of SAR and trajectory inclination angle is also deduced, which can provide useful guidance for trajectory design.Aiming at the problem of missile-borne SAR imaging with the constant acceleration trajectory, the RMA, RD, and modified CS algorithms with acceleration parameter are deduced and put forward based on the spectrum characteristic analysis of echo signal. The effects of acceleration are compensated directly in the new algorithms and high precision two-dimensional image is obtained through accurate phase correction. The validity of the derived imaging algorithms are verified by simulations.Aiming at the problem of missile-borne SAR imaging with the variable acceleration trajectory, the effects of phase error caused by the missile's variable accelerated motion on imaging are analyzed. Missile-borne SAR constant acceleration imaging algorithms are generalized to imaging with variable acceleration trajectory by reasonable amendment. The effectiveness of the proposed algorithms are shown by simulation results.