多普勒效应对FMCW-SAR系统成像性能的影响分析
doi: 10.3724/SP.J.1146.2006.01025
Analysis of the Doppler Effect in FMCW-SAR and Its Influence on the Image of the System
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摘要: 该文结合机载连续波合成孔径雷达(FMCW-SAR)系统的成像原理，讨论了FMCW-SAR成像系统与脉冲SAR成像系统的不同，分析了载机运动所带来的多普勒效应对FMCW-SAR成像系统性能的影响，指出多普勒效应会带来距离向与方位向信号的二次耦合，进而会影响图像在距离向和方位向的聚焦。然后，根据FMCW-SAR的回波特性给出了一种在回波信号方位向多普勒域对误差进行补偿的方法，并结合RD算法给出了整个成像系统的流程。最后给出了补偿前后算法仿真和验证的结果，可以看出对多普勒效应进行补偿之后能够消除距离向与方位向信号二次耦合带来的误差，提高成像质量。Abstract: Sawtooth signals are transmitted and received continuously in FMCW-SAR, which makes the character of the echo of FMCW-SAR is different from pulsed SAR. Combined with the imaging principle of FMCW-SAR, the influence of Doppler effect on FMCW-SAR imaging system is analyzed in this paper. It is pointed out that second coupling of range and azimuth signals may be caused by Doppler effect and defocusing of the image may be caused by it. An approach to compensate for the Doppler effect in the azimuth Doppler domain is presented and the flow chart of the RD algorithm for the FMCW-SAR imaging system is given out. Experimental results show that the Doppler effect and second coupling of the range and azimuth signals may be compensated by the approach presented in this paper and better images could be formed.
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