Research On The Key Technology Of Spaceborne High Resolution Wide Swath System

Aiming at the inherent contradiction between high resolution and wide swath in traditional single-channel spaceborne synthetic aperture radar(SAR)system,several signal reconstruction algorithms based on azimuth multi-channel system are proposed.On this basis,the motion-adapted signal reconstruction algorithm is derived.Combined with displaced phase center antenna(DPCA),HRWS-DPCA which can be used in high resolution wide swath(HRWS)system is obtained.The effectiveness and feasibility of the algorithms are verified by simulation experiments.the main achievements of this paper are as follows:(1)The contradiction between high resolution and wide swath of traditional single-channel spaceborne SAR system is analyzed.The signal model of azimuth multi-channel system is established,and the echo signal is decomposed into non-ambiguity part and ambiguity part.The relationships among pulse repetition frequency(PRF),radar velocity as well as the number and length of channels are discussed.Under different PRF conditions,the reconstruction effects are predicted according to space-time sampling relationship,eigenvalue distribution and phase distribution.(2)According to the steering vectors with different ambiguity number,the weight vectors of each signal reconstruction algorithm are deduced based on the principles and cost functions.Through simulation analysis,the reconstruction effect of each algorithm is verified under different PRF conditions,and the performance of each algorithm in peak sidelobe ratio(PSLR),azimuth resolution,signal to noise ratio(SNR)and signal to ambiguity pluse noise ratio(SANR)is compared.(3)On the basis of the range-Doppler signal model and combining the characteristics of the Relax algorithm,a HRWS imaging method based on Relax algorithm is proposed.The ambiguity component is suppressed by iterating,and the iterative process of the algorithm is described in detail.By the simulation,and comparing with the maximum signal method,the effectiveness and superiority of the new algorithm is verified.(4)Based on the traditional HRWS signal reconstruction algorithm,the motion-adapted signal reconstruction algorithm is deduced.Combining with DPCA,the moving target detection algorithm for HRWS system is proposed,the flow chart of the algorithm is designed,and the feasibility and validity are verified by simulation.Finally,the performances of the algorithm in PSLR,azimuth resolution,SNR,SANR and signal to clutter pluse noise ratio(SCNR)under different radar cross section(RCS)are compared.