LFMCW SAR调频非线性的等效分析方法

摘要

The linearity of linear frequency modulated continuous wave synthetic aperture radar (LFMCW SAR) is an important index to measure the linear frequency modulated (LFM) signal and can cause great effect on imaging quality of SAR. Aiming at nonlinearity of LFMCW and combining the characteristic of LFMCW SAR system, nonlinear frequency error is analyzed and sidebands effects of frequency fixing with different reference signal are discussed. An equivalent approach to transform nonlinear frequency error into addictive noise by virtue of phase errors is proposed and effect of equivalent noise on LFMCW SAR range resolution is analyzed through simulation. Results demonstrate that lower linearity can cause larger effect on beat frequency and signal-to-noise ratio (SNR). The proposed method can provide new thought for the elimination of nonlinearity influence based on signal processing.%针对LFMCW的调频非线性问题,结合LFMCW SAR成像系统特性,分析了非线性频率偏移的影响,讨论了选择不同参考信号进行混频情况下的边带效应,提出了一种将非线性频率误差通过相位误差转化为加性噪声的等效分析方法,并通过仿真分析了该等效噪声对LFMCW SAR距离分辨率的影响.结果表明,较低的线性度对差拍频率和信噪比影响很大.该方法可为基于信号处理消除非线性误差的影响提供新的思路.