This paper addresses the recognition problem of velocity gate pull-off (VGPO) jamming from the target echo signal for the velocity-based tracking system. The discrete chirp-Fourier transform (DCFT) is studied in this paper to jointly estimate the chirp rates and frequencies of the target and jamming signals. Firstly, the scaling characteristic of the DCFT algorithm is explored. Then, we focus on the quantitative effect of the VGPO jamming signal by analyzing the jointly estimated results in each pulse. The quantitative effect indicates that, as long as the estimated frequency is unchanged, the relationship between the estimated chirp rate and the pulse numbers is similar to the relationship between the frequency offset of VGPO jamming and the time. Finally, by utilizing the joint estimated results in each pulse repetition interval and calculating the mean square to variance ratio (MSVR) of the normalized estimated chirp rate, the VGPO jamming can be recognized. Simulation results show that the jamming signal and the target echo become distinguishable with the proposed feature. Comparing to the existing works, the proposed method can correctly recognize the jamming signal with lower jamming-to-noise ratio (JNR) 5 dB with less data needed, which means it can work effectively in the early stage of interference implementation and shows great potential in practical applications.

本文针对基于速度的跟踪系统，从目标回波信号中解决了速度门拉闸（VGPO）干扰的识别问题。本文研究了离散线性调频-傅立叶变换（DCFT），以联合估计目标信号和干扰信号的线性调频率和频率。首先，探讨了DCFT算法的缩放特性。然后，我们通过分析每个脉冲中的联合估计结果，重点关注VGPO干扰信号的量化效果。定量效果表明，只要估计频率不变，估计线性调频率与脉冲数之间的关系就类似于VGPO干扰的频率偏移与时间之间的关系。最后，通过利用每个脉冲重复间隔中的联合估计结果并计算归一化估计线性调频率的均方差比（MSVR），可以识别VGPO干扰。仿真结果表明，所提出的特征使干扰信号和目标回波变得可区分。与现有工作相比，该方法能够以较少的数据正确识别出具有较低干扰噪声比（JNR）5 dB的干扰信号，这意味着该方法可以在干扰实施的早期阶段有效地发挥作用，并显示出巨大的潜力。在实际应用中。仿真结果表明，所提出的特征使干扰信号和目标回波变得可区分。与现有工作相比，该方法能够以较少的数据正确识别出具有较低干扰噪声比（JNR）5 dB的干扰信号，这意味着该方法可以在干扰实施的早期阶段有效地发挥作用，并显示出巨大的潜力。在实际应用中。仿真结果表明，所提出的特征使干扰信号和目标回波变得可区分。与现有工作相比，该方法能够以较少的数据正确识别出具有较低干扰噪声比（JNR）5 dB的干扰信号，这意味着该方法可以在干扰实施的早期阶段有效地工作，并显示出很大的潜力。在实际应用中。