【作者】 罗勇江；

【导师】 赵国庆；

【作者基本信息】 西安电子科技大学 ， 电路与系统， 2011， 博士

【摘要】 在现代电子战中,复杂的电子侦察环境要求雷达侦察接收机不仅要具有大带宽,而且要对信号具有高截获概率和多信号处理的能力。传统的模拟和窄带侦察接收机已经很难适应需要,宽带数字侦察接收机已经开始逐步替代传统接收机并成为电子侦察发展的必然。宽带数字侦察接收机是现代电子战系统的重要组成部分,它采用高速的A/D转换器将模拟信号转换成数字信号,应用数字信号处理技术完成对信号的分析和识别,能够在很宽的带宽范围内对电子环境进行监测,对侦收信号进行快速、高效的测量和分析,具有软件无线电的应用优势。目前,对宽带数字侦察接收机的研究已经称为电子侦察领域的重要课题。本文在前人研究成果的基础上,研究了宽带数字侦察接收机的高效实现,并结合具体工程实践,对接收机中若干关键技术进行了研究和创新,且对无源侦察定位系统中的辐射源到达时差问题进行了分析和讨论,主要研究内容包括以下几个方面:1)分析和讨论了基于多相滤波器组的宽带数字信道化接收机实现结构。多相滤波器组可以改进传统FIR滤波器组结构,减少滤波器的计算量和简化结构,从而减少系统实现的资源开销。在这种信道化接收机中,信道数与多相结构的抽取率相同,它们与信道化接收机的时频分辨之间存在相互制约,因而在进行信道化设计时需要权衡考虑。2)设计了一种采用全并行方式实现短时傅里叶变换(STFT)结构的宽带数字信道化接收机。STFT结构的信道化接收机是利用傅里叶变换对整个接收带宽进行均匀信道划分。目前高速A/D转换器的采样速率可以达到1Gsps甚至几Gsps,而FFT运算模块的运行速度要远远低于这些高速A/D转换器的采样速率。为了解决高速A/D转换器与FFT运算模块之间的配合问题,文中给出了采用对数据进行缓存和降速的结构,通过全并行方式进行FFT运算,讨论了在数据不堆积的情况下,采用流水方式处理的过程和对数据缓存的要求及其时序关系。3)提出了一种高效的宽带数字信道化接收机实现方案。该方法利用多相结构改进STFT实现宽带数字信道化接收机,集合了多相滤波器组和STFT两种结构的优点。该结构对傅里叶变换采用多相方式进行展开,应用多路抽取并行运算实现傅里叶变换,从而减少了STFT的数据运算量。且抽取操作降低了傅里叶变换的运算速度,实现对STFT结构信道化接收机的优化,减少所需要的硬件资源开销,而其性能与全并行结构的STFT信道化接收机一致。最后,根据实际工程需要,设计了多相结构的STFT信道化接收机原理样机,并通过工程实验验证了其有效性。4)研究了宽带数字接收机中的信号脉内特征提取技术,分析了雷达常用信号分别在相位差分法和小波脊分析法中最小二乘估计的脉内特征,构建了它们的特征参数集合,并由此实现对雷达常用信号调制类型的自动识别和分类。针对接收机中同时接收到多个信号混叠时的信号调制类型识别问题,提出了利用最小互信息准则下的独立分量分析,在多维观测数据条件下实现多个独立信号或者信号分量的盲分离,进而将多信号混叠时的调制类型识别转化为多个单信号的调制类型识别。最后,运用信号脉内特征提取技术,实现了无先验信息条件下多信号混叠时的信号调制类型的自动识别和分类。5)针对无源侦察定位系统中多Chirp信号混叠时的站间到达时差估计问题,提出了利用自适应Chirplet原子分解对混叠信号进行估计和分离,然后利用最大似然条件下的相关法实现对各Chirp信号的到达时差估计。原子分解是利用与信号分量具有相近特征的向量或者函数来描述信号。利用Chirplet原子来分解Chirp信号具有较好的时频内聚性,对多Chirp信号的自适应Chirplet原子分解是最大似然条件下Chirplet原子对相应Chirp分量的逼近。最后,利用自适应分解后得到的原子进行相关处理,可以估计出各信号的站间到达时差。6)针对无源侦察定位系统中对噪声调频干扰源的定位问题,提出了采用增量调制编码对接收到的噪声调频信号进行编码和传输,利用最大似然条件下的相关法完成对噪声调频干扰源的站间到达时差估计。采用增量调制编码对噪声调频信号进行编码可以大大降低无源侦察定位系统中的数据传输量,且编码后的序列仍然保持了噪声调频信号的近似统计特性。文中推导了利用增量调制编码序列估计噪声调频干扰源站间到达时差估计的克拉美-罗下界。利用最大似然的相关法能够估计噪声调频干扰源的站间到达时差,其性能接近直接采用原始数据进行相关运算估计的到达时差。最后讨论了抽取和插值处理对到达时差估计的影响。更多还原

【Abstract】 Electronic warfare is more complex than ever before, EWRR(Electronic War Reconnaissance Receiver) is the import part of the electronic detection system for radar signal. In many radar countermeasure applications, it requires characters of EWRR that wideband, catch low probability of intercept radar signal, processing multiple signals. Traditional analog receiver has many disadvantages, so it was only used in some simply application. With the rapid development of digital techniques, EWRDR(Electronic War Reconnaissance Digital Receiver) is take a very important roles in modern electronic war. EWRDR has advanced architecture than Traditional analog receiver, it use analog-digital-converter to convert analog to digital signal, and the outstanding advantage is that it can amalgamate the high performance of soft-radio. With the using of digital signal processing techniques, EWRDR can analysis character of signal and measure property of signal in detail with high efficiency, and it even can recognize signal, also can monitor the environment of electronic in a large frequency band. So studying EWRDR with high performance and its application is very important to adapt modem complex electromagnetism environment.Based on the previous works, this paper primarily researches the high efficiency application of EWRDR associating actual projections, investigates the key technologies and implementations of EWRDR. The main works can be summarized as follows:1. The architecture of channelized receiver based on poly-phase filters is analysis. The poly-phase filter can improve the performance of traditional FIR filter, it can reduce the calculate work and simply the architecture of receiver. So, with the advantage of poly-phase filter, the system resource of receiver is less than trandition receiver . In the receiver based on poly-phase filters, the number of receiver channel is equal the decimation of poly-phase filter. The number of channel or decimation of poly-phase filter will cause the conflict of resolution between time and frequency domain. So, the selection of channel number is need to think about with careful.2. The architecture of channelized EWRDR receiver based on full parallel STFT(Short Time Fourier Transform) is provided. With the advantage of STFT, this architecture realized uniformity channel, every channel has same parameters except carrier frequency. The sample rate of ADC is up to Gsps now, even several Gsps, but the operation speed of FFT block is large lower than GHz. So, it is necessary to find some solution to match the speed of ADC and FFT block. With the help of multiple FFT blocks operation paralleled, the speed of data operation can be slow down, and each FFT block also work with lower operation clock. Full parallel processing mode with pipeline operation is provided in this paper, and its timing characters is also discussed.3. A novel and high efficiency architecture of channelized EWRDR is provided, poly-phase is employed to optimize normal channelized receivers based on the STFT. In this architecture, advantages of poly-phase filter and STFT are combined together. First step of this method is decimate time-domain data with poly-phase processing, then apply Fast Fourier transform (FFT) using decimated data, final weight for transform result. Using theory of poly-phase, the STFT can be expanded to another form. With the help of multiple parallel FFT block and decimation operation, the throughput of FFT operation can be reduced largely. The performance of receiver by new method is as same as the receiver by STFT, but the spending of receiver is more lower. The experiments with actual receiver based on new architecture shows the method is correct and its efficiency is higher.4. The processing algorithms of phase-differential and wavelet based on minimum square is presented to classify difference modulated signal. Features of some typical radar signals based on phase-differential and wavelet are discussed. And then, the method of classification of signal mixed with multiple different modulated components is presented. Under the condition of multiple dimension observed data, using ICA(Independent Component Analysis) based on minimization of mutual information, it can achieve the blind signal separate of multiple independent signal. With the help of ICA, the method of classification of signal mixed with multiple different modulated components can be convert to classify several single signal modulation. And then, the signal modulation can be recognized by signal features. The processing algorithms of phase-differential and wavelet based on minimum square is presented to classify difference modulated signal. The signal features analysis by phase-differential and Morlet wavelet is also discussed. Thus, without the beforehand information of signals, the algorithm adopting ICA and phase-differential or wavelet implements the automatic classification of mixed signal by difference modulation.5. The adaptive chirplet atomic decomposition is used to analyze the separation of multiple Chirps. After separation of signals, the TDOA(Time Difference of arrival) of each Chirp can be estimation based on maximum likelihood correlation algorithm. The basic way of atomic decomposition is that signal can be described by some components with same features as signal. Chirp shows assembly feature of time-frequency if it decomposed by chirplet atoms. Under condition of maximum likelihood, some Chirps mixed signal can be decomposed by adaptive chirplet atom, each Chirp component can be approached by one chirplet atom. In passive location system, compute the correlation of each pair atoms between main-receiver signal and sub-receiver signal in mixed Chirps, the TDOA of each Chirp can be estimated.6. To locate noise-frequency modulation jammer with TDOA in passive system, a new method of delta-modulation coding jointed cross-correlation is presented in this paper. Signal can be described by delta-modulation code, and coding sequence of sub-receiver is send to main-receiver. Using coding sequence and maximum likelihood correlation algorithm, TDOA can be estimated. The advantage of delta-modulation code is that it can reduce communication data traffic between main-receiver and sub-receiver. After coding, the sequence of noise-frequency modulation signal hold similar statistics feature of raw data. The TDOA estimated by coding sequence is same as that of the method of cross-correlation using signal sample data. Finally, the method of decimate coding sequence and interpolate correlation are analysis, and the effect of TDOA in this method is discussed.更多还原