Study On Imagine Algorithms For Maneuvering Flight Synthetic Aperture Radar

Synthetic Aperture Radar(SAR)can carry out long-range high-resolution imaging in all day and all weather.The maneuvering flight SAR imaging technology,which combines maneuvering platform with SAR,has the advantages of flexible maneuvering and advanced observation(high squint),and has become a research hotspot at present.Maneuvering flight SAR exists conventional models and algorithms mismatch and motion error caused by atmospheric turbulence.In the thesis,the mathematical model,echo characteristics,imaging algorithm and motion error compensation algorithm are theoretically analyzed and simulated,which meet the development needs of maneuvering SAR imaging technology.The main research contents are as follows:Aiming at the problem of conventional model mismatch,the thesis builds a geometric model of maneuvering flight SAR imaging based on the motion characteristics of maneuvering flight SAR,and establishes the range model of the slanted range plane by using space vector decomposition.Aiming at the mismatch of conventional algorithms,a SAR imaging method for maneuvering flight based on Polar Format Algorithm(PFA)is proposed.Firstly,a modified twodimensional interpolation function is obtained by using the two-dimensional Taylor series expansion of the slanted range plane,and then the maneuvering acceleration information is introduced to correct the two-dimensional mapping function,which solves the problem of azimuth space variation and cross-coupling of the high squint SAR in maneuvering flight The modified PFA is more suitable for undulating terrain because the range expansion of the slanted range plane contains the height information.The simulation results show that the PFA-based maneuvering flight SAR imaging algorithm has good focusing effect and focusing depth.Considering the motion error of maneuvering flight SAR in practical application,a motion compensation algorithm combining modified PFA is proposed.First,by analyzing the maneuvering flight SAR actual traj ectory and ideal trajectory position error,using space-variant and invariant error components to build the maneuvering flight of SAR motion error model,and space-variant and invariant error components to build the maneuvering flight of SAR motion error model,and then through the data of inertial navigation system parameter fitting get space-variant and invariant error polynomials.Finally,the two step motion compensation algorithm is combined with modified PFA,which effectively eliminates the influence of motion error on the results of maneuvering flight SAR imaging.Experimental simulation data and measured data demonstrate the effectiveness of the algorithm.