Abstract: Distance resolution and system SNR are directly affected by FM characteristic of the Linear Frequency Modulation Continuous Wave（LFMCW） radar level gauge.In this paper，an evaluation function for frequency modulation linearity is constructed by using the spectrum characteristic of beat frequency signals.Later，Immune Mind Evolutionary Algorithm（IMEA） is introduced to optimize the end coordinates of the subsections to get nonlinear curve of frequency modulation voltage so as to compensate for the nonlinearity of VCO.Experiments show that the proposed method has good performance with no additional requirement for hardware and time cost，and the linearity and Signal Noise Ratio（SNR） of the system has been improved prominently.

摘要： 线性调频雷达物位计的调频特性直接影响着系统的距离分辨力和信噪比，通过提取零差拍信号的频谱特征，构造衡量调频线性度的评价函数，利用免疫思维进化算法对调频电压曲线分段端点进行寻优，获得非线性的调频电压曲线，来校正压控振荡器的非线性，优化系统的调频特性。实验结果表明，该方法具有良好的效果，在不增加任何硬件设备的基础上，可显著提高系统的调频线性度和信噪比。