【作者】 常虹；

【导师】 赵国庆；

【作者基本信息】 西安电子科技大学 ， 信息对抗， 2011， 博士

【摘要】 随着电子战信号的日益密集,信号形式的日益复杂,开展对复杂未知环境下的信号侦察,寻求截获、估计、分选多信号的方法,已成为当前电子侦察领域紧迫而艰巨的任务之一。数字接收机技术及阵列信号处理技术的发展,使得灵活运用各种处理算法实现宽开侦收成为可能,论文研究了复杂电磁环境下宽开侦收的关键技术,主要包括数字信道化接收机的实现算法、及信道化输出信号的检测、编码技术,时空欠采样条件下的信号参数无模糊估计算法等内容。本文的目的是研究对雷达信号的时、频、空三维宽开侦收处理算法,论文具体内容包括:1在宽带接收中,研究了基于STFT(短时傅里叶变换)的数字信道化实现方法,在介绍了现有的加权叠接相加实现结构的基础上,分析其特点及其存在的问题,接着给出了一种基于多相分解的实现结构,该结构可以在相同的系统资源下实现更高的频率分辨率。考虑到各子带中心频率均匀分布的情况,给出了一种基于递归算法的STFT实现方法,通过与现有结构的比较,新结构具有高效灵活的特点。以射频脉冲信号为对象进行信号检测和主要特征参数测量,形成辐射源检测结果和PDW(辐射源脉冲描述字)的估计。2针对时域欠采样条件下的频率估计模糊问题,提出了基于双欠采样通道输出互谱插值的频率估计方法,考虑到同时多信号时,存在伪谱峰的问题,提出了在互谱峰值附近设置MUSIC(多重信号分类)谱搜索区间的方法,亦能解决MUSIC谱搜索对欠采样信号频率模糊区间定位的问题,同时在降低搜索量的情况下提高了频率估计精度,以上方法都是以两个欠采样通道为基础。在单欠采样通道并附加延时通道的条件下,提出了基于延时和ESPRIT (旋转不变子空间)算法的欠采样频率估计方法,欠采样所引入的频率模糊可以通过延迟相位差来加以消除,相比已有算法,本文算法在保持好的参数估计性能的同时降低了运算复杂度。3研究了空域欠采样条件下方向角无模糊估计问题,根据传统的相位干涉仪的数学模型,分析了比相法测向原理及其测量误差与哪些因素有关;利用环阵各阵元间的互功率谱相位实现信号的DOA(到达角)估计,提出了适合“无模糊测向”阵列配置条件,以上方法均利用相关相位测向,在多信号情况下,信号之间的互扰使测向性能欠佳,所以通常是结合信道化技术实现频域多信号分离后再利用相位法测向。针对多信号情况,利用线阵的时空DOA矩阵特点,提出了同时多个非相干信号无模糊测向算法。4针对多参量联合估计问题,研究了极化—相位干涉仪的信息构成,提出基于该阵列的信号的二维DOA与极化联合估计。分析了时空欠采样条件下宽带阵列信号模型,提出了基于延时自相关的宽带LFM信号的参数联合估计方法,针对多信号干扰情况,利用TRD (时间-调频斜率分布)良好的聚焦性,求各阵元输出信号的TRD变换,谱峰反映信号的调频斜率,取各阵元对应同一谱峰处的相位差为该谱峰对应的调频斜率与信号到达两阵元的时延的乘积,分析表明,将TRD变换和比相法结合实现了宽带信号的参数联合估计。综上所述,本文的研究内容主要集中在宽频段接收时参数无模糊估计方法,因此可以把本文的研究内容统称为宽带侦收方法研究。更多还原

【Abstract】 With increasing complexity and denseness of battle electromagnetic signals in modern EW, the research of signals reconnaissance,such as signal interception, parameter estimation,and signal sorting is one of the major tasks in electronic reconnaissance under the unkown electromagnetie circumstance. With the development of digital receiver and array signal processing, it is possible to use many processing algorithm flexible to ensure the wideband receiver. A series of key technologies of wideband receiver in complex electromagnetic environment, including algorithm employed to optimize channelized receivers,signal detection and coding, algorithm of non-aliasing parameters estimation with spatial-temporal sub-Nyquist sampling, etc., are mainly researched in this dissertation.This dissertation is devoted to research the algorithm of temporal-frequency -spatial wideband reconnaissance. The main contributions can be summarized as follows.In the aspect of wideband receiver, technology of digital channelization based on STFT (Short Time Fourier Transform) is discussed. The charateristics and existing problems of an efficient channelized receiver structure with weighted overlap-add filterbank to be solved are pointed out. Based on above discussion an architecture based on polyphase decomposition is proposed,which can realize frequency measurement with high accuracy under the condition of the same system resource. In the aspect of all-central frequency of subbands with uniform distribution, a recursive algorithm is proposed. Performance comparison has shown that the proposed structure is of relatively more flexible and higher efficiency. Modern electronic interception systems perform the tasks of detection and main parameters estimation for radio pulse signal. The encoder clusters all the feature vectors belonging to the same signal and estimates PDW (Pulse Descriptor Word).For the problem of frequency aliasing with temporal sub-Nyquist sampling,a method based on cross spectral interpolation from two independent sampling channels for frequency estimation is proposed. Considering spurious peaks when multi signals simultanoues existing, a method of select frequecy range around each cross spectral peak before using MUSIC(Multiple Signal Classification)algorithm to complete frequency search is provided, which can solve the problem of aliasing zone location and improve frequency estimation. Two methods mentioned above are all working on two sub-Nyquist sampling channels. A novel frequency estimation approach based on an auxiliary time-delay channel and ESPRIT(Estimation of Signal Parameters via Rotational Invariance Techniques) algorithm for wideband signal with sub-Nyquist sampling is proposed. With the aid of information provided by the auxiliary delayed sampling channel, we call solve the frequency aliasing. Comparison via simulation has shown that the proposed algorithm is of relatively low computational complexity and the same high performance.The problem of unambiguous angle estimation is studied. The theory of phase comparison approach and the factors that can affect the measurement errors are discussed based on the mathematical model of traditional phase interferometer. An algorithm to estimate DOA(Direction Of Arrival) based on crosspower spectrum phase is proposed and a necessary condition of array antennas configuration is also provided. The two approaches all perform DOA estimation with cross-correlation phase. The estimation will not be precise because of the interferences among multi signals. This problem is solved by using digital channelized receiver. For multiple noncoherent signals, a novel unambiguous DOA estimation is proposed by exploiting the characteristic of space-time DOA matrix.To multi parameters estimation, the information structure of the polarization-phase interferometer is analyzed, two dimension DOA and polarization estimation are presented. The wideband model of the array outputs with spatial-temporal sub-Nyquist sampling is discussed.And then, joint parameters estimation for wideband LFM signal based on delay and auto-correlation calculation is performed.To multi signals interference, TRD (Time-Frequency Rate Distribution) of each sensor can be obtained. Because the TRD of LFM signal possesses the cluster characteristic related to the frequency rate,the spectrum peak in the TRD expresses signal frequency rate.The phase difference of each sensor at the same spectrum peak is the product of the frequency rate and time delay.We have proved that combination TRD transformation with phase comparison approach can be implemented for joint estimation.In conclusion, this dissertation describes several methods of unambiguous parameters estimation in the wideband receiver.All these methods can be treated as wideband interception methods.更多还原