【作者】 王俊；

【导师】 张守宏；

【作者基本信息】 西安电子科技大学 ， 信号与信息处理， 1999， 博士

【摘要】 对雷达信号进行积累以增加实际利用的信号能量，是提高检测性能的有效手段。积累过程中对信号非平稳特性的分析和处理是比较重要的。本文从微弱目标信号检测的新理论和新方法研究出发，结合非平稳信号的时频分析方法和长时间信号积累技术在雷达信号检测中的应用，从匹配滤波的实现以及长时间相参以及非相参积累检测中的运动补偿等问题进行了研究，主要内容概括为： 第一章绪论，论述了研究的目的、背景和意义。 第二章利用相控阵雷达可实现的多波束驻留工作方式或常规雷达小角域扇扫或烧穿的工作方式，针对长观测时间内对雷达目标回波信号的积累检测，提出一种基于距离拉伸和联合时频分析的包络移动补偿方法。该方法不需要对目标的运动参数进行预估计，而是将目标的多脉冲回波作为暂态信号，通过时频联合处理来进行运动补偿和匹配积累和检测，这种方法适用于存在多普勒走动的情况。 第三章利用一种宽脉冲等效法来避免雷达多脉冲目标回波积累检测时的距离走动现象，通过宽发窄收方式，在扫描或波束驻留过程中以步进频率同时或序贯发射宽脉冲，而以综合的方式来形成窄的接收脉冲，而在综合前对宽脉冲进行处理以使得目标在一定的观测时间内不发生距离走动，在不考虑回波包络延时的情况下该方法容易获得较长的积累时间。 第四章将长时间雷达信号回波模型推广到非线性频率调制的情况，基于自适应子波局域优化逼近的特性，提出了利用自适应子波变换的方法来实现对机动目标回波信号进行长时间相参积累相位补偿的方法。AWT方法具有自适应局域分割、快速变换实现，运算量小性能良好的特点，利用自适应子波技术能更充分地利用回波信号的能量，从而可进一步提高对微弱机动目标的检测能力。 第五章针对实际应用的需要，结合高分辨雷达体制目标强散射中心模型和非相参积累技术，讨论了强背景下低速海面雷达目标的检测与分离问题，并给出了一种低速海面目标的检测与分离方法，它可以克服低擦地角情况下海尖峰对目标检测可能引起的虚警。同时给出了一种时变海杂波数据的仿真方法。 第六章讨论了通过信号特征的提取来实现在低信噪比下信号的波形恢复及检测方法，通过一种实用的子波去噪算法，与Donoho等人的方法进行了比较，在对非光滑信号的去噪处理时该方法具有有较小的估计方差以及较好的边缘恢复特性，而 o且能够提供待检信号在强噪声背景中有用信息的准确定位，可应用于对冲激雷达回波和地震探测等回彼信号中的信息提取及去噪。 第七章研究了Gabor变换在微弱暂态信号检测中的应用问题。在现有方法的基础上，对模型失配误差对检测性能的影响作了进一步深人的分析，椎导了非中心化参数的成立条件并详细分析了两种情况下的暂态检测器的性能。针对临界采样Gabor变换对偶窗函数与分析函数不同时具有良好的时频局域性问题给出了一种改进方法，该方法的综合函数与分析函数可以同时具有良好的局域性能。 第八章从子空间匹配投影的角度研究了一种基于线性时频变换信号子空间匹配投影的暂态信号检测方案，推导了线性时频域上两种信号的匹配检测器的快速实现形式并进行了性能分析。该方法是传统匹配滤彼技术在线性时频域上的推广实现。 最后，对全文工作进行了总结，并提出了对进一步研究方向的看法。更多还原

【Abstract】 An efficient method to improve detection perfonnance of radar signals is to enhance available energy returned from targets by integration, where performance is depend the utilization of non- stationaiy properties. Focussing on applications of time-frequency analysis and long t~m ~oh~uit signal integration techniques, this diss~tation investigates the methods for realization of matching filter and issues of motion compensation techniques for long tarn integration detection. ~ main contents of the dissertation are descnl,ed as followin& Firstly, a biief introduction of the puipose, backgrntmd and significance of the ~~rks in this disseitation is concerned. For integral detection of ~ak moving targets using multiple dwelling beamfomis of phased array radar or staring mode of conventional radar, a motion compensation way for range migration by anploying range cells stretching and joint time-frequency is established in chapter 2. With no r&p駌ernent on the knowledge a priori of target motion parameters, the provided method takes returned signals of multiple range resolution cells as transient signals, and make use of combined processing in time and frequency domains to compensate the envelop delay ezTors, and to proceed the coherent integration detection. The joint time-frequency processing based method fit into the circumstances where divergent doppler resolution units of target are presented. In chapter 3, An equivalent wide-pulse technique with range resolution capability is proposed to overcome the effect of range migration on low observable target detection using long-tam coherent integration. This method utilizes both simultaneously and sequentially stepped frequency signals to synthesize a narrow pulse in receiver while canying out coherent integration against each individual component, a woxking mode by emitting in wide and receiving in narrow. The advantages over those available methods is it achieves long integration time while possesses range and velocity resolution capabilitie& Chapter 4 proposes a novel long-term coherent integration method for detection of weak non- linear frequency modulated (NLFM) signal returned from low observable maneuvering target The method exploits the time-frequency tiling property of adaptive wavelet transform for the extended NLFM signal model, and is practically realizable. The unitary and linear phase wavelet basis function together with joint one order linear approaching procedure are presented to pursuit the signal trace in time-frequency plane. Additionally, dechirping transform is employed in subband outputs to achieve ABSTRACT the low computational complexity implementation. Simulation results demonstrate the efficacy of the proposed AWF based detector. In accordance with need of an actual application and based upon the prominent scatterer model of high resolution radar, chapter 5 investigated a practical detection and distinction method for sea- surface moving target at lower speed by using integration techi黴ue~ togethering with radial range carelation information to reduce false alarm resulted from sea-spike echoes when radar beamfocm working at low scraped angle. A simulation method of sea clutter data is also concemecL In chapter 6, a waveform detector is considered by discernment of the difference of modulus maxima evolution behaviors between signal and rarxlom noise in multiscale space and a practical noise rumval algorithm is given too. In comparing with one using更多还原