短程宽带FMCW雷达信号非线性校正方法研究

调频连续波（Frequency Modulated Continuous Wave，FMCW）合成孔径雷达（Synthetic Aperture Radar，SAR）具有重量轻、截获概率低、高分辨率成像等优点，但其发展受到限制的一个重要因素是发射信号中存在非线性误差。本文针对一部X波段4.8GHz带宽短程调频连续波成像雷达系统中非线性误差较大的问题，提出了一种基于高阶模糊函数（High-order Ambiguity Function ，HAF)和重采样的非线性误差校正方法。该方法结合压控振荡器( Voltage Controlled Oscillator，VCO)的频率电压特性将非线性差频信号拟合为多项式相位信号（Polynomial Phase Signals，PPS），利用HAF对多项式相位系数进行估计，并利用插值完成非线性误差校正。仿真和实测数据处理结果表明，该方法能准确有效地校正FMCW系统中的非线性误差，且工程适用性强。 

Research on Nonlinearity Correction of Short-Range Wideband FMCW Radar Signal

The combination of frequency-modulated continuous-wave (FMCW) technology and synthetic aperture radar (SAR) techniques have a lot of advantages, such as light weight, low probability of intercept and high resolution imaging. One limiting factor to the use of FMCW sensors is the presence of nonlinearities in the transmitted signal. In order to analyze the problem of large nonlinear error in frequency modulated continuous wave imaging system with X-band and 4.8GHz bandwidth, a nonlinear correction algorithm based on high order ambiguity function and resampling is proposed. Polynomial-phase signals are fitted by the nonlinear beat-frequency signals combing with frequency-voltage character of voltage controlled oscillator in this paper. Polynomial-phase coefficients are estimated by HAF, and then nonlinear error is corrected by interpolation method. The experimental results based on simulation and real data indicate that this method can correct the nonlinear error with high precision and strong engineering applicability can solidly and effectively corrects the nonlinear error in FMCW system.