间歇采样转发干扰参数估计算法研究

Study on Parameter Estimation Algorithm for Interrupted-Sampling Repeater Jamming

  • 摘要: 基于数字射频存储器的间歇采样转发干扰作为一种新型相干干扰,具有相关性强、参数变化快的特性。这种干扰可通过设置干扰切片的宽度、数目以及转发次数同时达到欺骗和压制两种干扰效果,从而对现代雷达系统构成显著威胁。由于这类干扰的变化复杂且迅速,传统的单一抗干扰手段难以稳定有效地应对,因此,基于干扰参数的先验信息,动态调整抗干扰策略,成为了一种更为可靠和有效的解决方案。该文针对间歇采样转发干扰的参数估计问题,设计了一种基于Dechirp-STFT的间歇采样转发干扰参数估计方法。该方法首先采用短时傅里叶变换对解线调后的干扰信号进行时频分析,得到具有干扰信号时宽和时延特征的时频分布图,并根据干扰的时宽和时延特征进行干扰参数粗估计,估计出切片数目;随后,为提升在低干噪比下干扰参数估计性能,对接收回波信号进行时域反卷积处理,其在干扰切片的前后沿处会形成冲激脉冲对,利用冲激信号相比于sinc包络信号能量更为集中的特点进行参数精确估计,通过冲激脉冲对数和时宽估计干扰转发次数和切片宽度;最后,通过蒙特卡罗实验和实测数据证明了该参数估计算法的有效性,并验证了其在低干噪比下具有良好参数估计性能,能为抗间歇采样转发干扰技术提供更精确、更可靠的先验信息。

     

    Abstract: ‍ ‍In the field of modern electronic warfare, interrupted-sampling repeater jamming based on Digital Radio Frequency Memory (DRFM) has gained prominence owing to its ability to create novel coherent jamming effects. This technique confuses enemy radar by intermittently sampling and retransmitting signals, disrupting their operations. Interrupted-sampling repeater jamming, with its strong correlation and rapidly changing parameter features, can effectively suppress and deceive radar systems by optimizing the width, numbers, and forwarding times of jamming slices, posing a serious challenge to the security of contemporary radar systems. Interrupted-sampling repeater jamming exhibits a high degree of complexity and rapid change, creating immense challenges for traditional, static interference mitigation methods. These methods are frequently unable to adapt to the swiftly evolving interference environment, making it difficult to ensure sustained, high-efficiency performance. To counter these changes effectively, it is crucial to implement a far more flexible strategy: utilizing known interference parameters as a basis for decision-making and dynamically adjusting and optimizing interference countermeasures. The capability of such strategies to be dynamically tuned enables them to quickly adapt to changes in the environment, thereby providing a solution that is more stable, reliable, and effective in the long term. The article proposes a parameter estimation method for interrupted-sampling repeater jamming based on dechirp processing combined with Short-Time Fourier Transform (Dechirp-STFT). Initially, the jamming signal was processed with dechirp processing, and a time-frequency analysis was performed on the processed signal using STFT. The key in this step was to generate a time-frequency distribution map that reflected the characteristics of jamming duration and delay. A coarse estimation of the jamming parameters was made through binarization of the time-frequency distribution map and based on the characteristics of signal delay and duration, determining the number of jamming slices. Subsequently, this study proposes a method that is built upon the coarse estimation information to further enhance the precision and performance of parameter estimation in low jam-to-noise ratio (JNR) environments. This involves processing the received echo signal with Time-Domain Deconvolution (TDC). A more accurate calculation of the number of jamming transmissions and the width of jamming slices was achieved by analyzing the logarithm and duration of the impulse responses obtained after TDC processing. Lastly, this study validates the effectiveness of the proposed algorithm through Monte Carlo simulation experiments and actual measured data. Even under low JNR conditions, the parameter estimation method maintains excellent performance. The experimental results show that when the JNR reached 5 dB, the method could estimate the number of jamming repetitions with more than 80% accuracy and had kept the estimation error of the slice width within 0.07 μs, providing more precise and reliable prior information for anti-interrupted-sampling repeater jamming techniques. In conclusion, the parameter estimation method proposed in this article offers strong technical support for radar systems facing complex intermittent sampling repeater jamming. With the continuous development of electronic warfare and technological progress, the parameter estimation method introduced in this paper is expected to be widely applied in future radar and electronic warfare systems, making a positive contribution to enhancing the survivability and anti-jamming performance of systems.

     

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