一种平行航线双基聚束式FMCWSAR的两步处理方法

A Two-Step Processing Approach for Parallel Bistatic Spotlight FMCW SAR Focusing

本文首先对基于调频连续波(FMCW)的平行航线双基聚束式SAR回波信号进行了建模,分析了雷达发射信号过程中载机连续运动带来的多普勒频移的影响.之后利用瞬时频率的概念,通过引入最近距离和、最近距离差以及半类双基角等变量,推导出平行航线双基聚束式FMCW SAR回波信号的二维波数域表达式,在此基础上提出了一种针对平行航线双基聚束式FMCW SAR数据的两步处理方法.两步处理方法首先通过方位预滤波处理实现方位谱解模糊,然后通过残余聚焦实现多普勒频移补偿以及双基的频率变标处理,同时,对方位预滤波处理各步操作引起的数据时频关系变化进行了分析.仿真数据处理验证了本文分析的正确性和算法的有效性.

This paper establishes the received signal model of parallel bistatic spotlight SAR adopting frequency modulated continuous wave（FMCW）, and analyzes the affect of doppler frequency shift introduced by platform＇ s continuous motion while radar transmitting and receiving signals. Then using the concept of instantaneous frequency and through introducing the parameters, i.e. the sum and difference of the closest slant range,and the half quasi bistatic angle,the received signal expression in two dimen- sional wave-number domain is deduced.Based on this, a two-step processing approach for parallel bistatic spotlight FMCW SAR fo- cusing is presented, which uses azimuth pre-filtering step to overcome azimuth spectral folding phenomenon first. Following this op- eration, a second residual focusing step is applied to carry out doppler frequency shift compensation and the bistatic frequency scaling processing. Meanwhile, the time frequency relations changing from each stage of azimuth pre-filtering are analyzed in detail. Simula- tion data processing verifies the analysis and the proposed algorithm.