雷达成像应用中会面临大斜视成像问题。大斜视情况下,目标回波信号谱在谱域中发生偏移,造成在有限的谱支持域中发生翻折和混叠,使得图像不能准确聚焦。通过斜视角计算偏移量,可恢复实际目标谱,进而采用距离徙动算法实现成像。该文通过分析大斜视下的信号谱及目标谱特性,详细说明了采样率和混叠的关系,并确定了距离徙动算法中的插值格点,减少了不必要的插值运算和插值误差,提升了成像处理效率。由于采用了谱域处理方法,未对距离方程进行近似,因此适用于处理远场与近场成像问题。仿真分析表明:文中所述处理方法可以有效完成近场大斜视情况下的精确聚焦成像,算法适用性广,且可实现快速处理。

In radar imaging applications, high squint imaging is an intractability problem. Since the spectrum of the target echo signal is shifted in spectrum support region, it causes spectral folding and aliasing, which in turn causes miss-focusing of the radar image. By calculating the shift offset according to the squint angle, the actual target spectrum can be recovered, and then the range migration algorithm can be used to realize the imaging. In this paper, the relationship between sampling rate and aliasing is described in detail by analyzing the signal spectrum and the target spectrum under high squint conditions, and the interpolation grids in the range migration algorithm is determined, which reduces the unnecessary interpolation procedures and interpolation errors, therefore the processing efficiency can be improved. The advantages of this algorithm is that it has wide applicability and can deal with far-field and near-field imaging problems because the method does not approximate the distance equation, and also fast processing is possible. The simulation results show that the proposed method can effectively achieve accurate focus imaging in the case of near strabismus.

TN957.52

国家重点研发计划资助项目;国防基础科研项目