Research On ISFT Imaging Algorithm Of GNSS Bistatic SAR

Bistatic synthetic aperture radar(BSAR)is a kind of synthetic aperture radar which is separated from the transmitting platform and the receiving platform.GNSS-BSAR system based on GNSS is a kind of passive dual base SAR system with special configuration.The GNSS navigation satellite is used as the transmitter,and the receiver can be installed on the satellite,aircraft,mobile landing vehicle,or even fixed on the earth surface.GNSS dual base SAR system has the advantages of low deployment cost,good security and so on.It has a wide application prospect in autonomous landing,autonomous navigation,battlefield terrain acquisition and so on.This system has the advantages of good security,low cost,good system stability,large constellation,short revisit time and flexible configuration.As a passive radar,GNSS-BSAR has the characteristics of good coverage,concealment and anti-jamming.In this paper,the spatial variability,SNR and spatial resolution of GNSS-BSAR system are analyzed and explained.Through the research on the back projection(BP)algorithm of the time domain GNSS bistatic SAR,the more accurate imaging of the bistatic SAR is realized.At the same time,the advantages and disadvantages of the BP algorithm and its application range are analyzed.The algorithm is verified by the point target simulation experiment,Because BP algorithm needs to be interpolated,the computation is very large,so the efficiency of this algorithm is not high,so this paper uses the algorithm of frequency domain to solve the efficiency problem,this paper proposes a frequency domain algorithm suitable for GNSS-BSAR system,this paper constructs the GNSS bistatic SAR imaging model of navigation satellite,uses the frequency domain algorithm,and uses the method of series inversion theorem In this model,the inverse scaled Fourier transform(ISFT)imaging algorithm is used.The results of simulation data processing verify the correctness of the algorithm.