基于瞬时互相关和STFT的LFM信号测向算法

A direction-finding method for LFM signals based on instantaneous cross correlation and STFT

现代电子对抗中,实现对线性调频(LFM)信号这种低截获概率雷达信号的精确测向已经非常重要.针对LFM信号提出一种无模糊、高精度的DOA估计算法.该算法首先计算单基线天线接收到的信号的瞬时互相关,然后通过短时傅里叶变换(STFT)提取互相关输出中的单频信号.利用该信号的频率与到达角之间单调的对应关系实现对到达角的无模糊估计.算法克服了相位干涉仪测向算法中存在的多值模糊问题,并且由于只需要单基线天线,所以能够应用于天线孔径尺寸受限的场合.对算法的性能进行了理论分析,推导了测向算法的精度和估计误差,并且理论推导了角度分辨率和测角实时性之间的量化关系,仿真实验结果表明了该算法的正确性和有效性.

In modern electronic counter measures, it＇ s of great importance to precisely estimate the BOA of LFM signals-a kind of LPI radar signal. A non-fuzzy and high precision DOA estimation algorithm for LFM signal is proposed in this paper, whereby the instantaneous cross-correlation of signals received by antennae is evaluated, and then the monochromatic signals are picked up with STFT. There is a unique correspondence between BOA and the frequencies of the monochromatic signals, which can be used to make an unambiguous DOA estimate. The proposed algorithm eliminates the ambiguity of multiple values that occur with a phase interferometer. And since it needs only a single baseline, the algorithm can be applied in situations where the physical size of the antenna is restricted. The performance of the algorithm was analyzed theoretically, and expressions for the precision and error of the estimation derived. Finally, a quantitative relationship between angle resolution and the real-time property of BOA was developed, and this formula is presented. Simulation findings prove the validity and effectiveness of this algorithm.