LFMCW雷达多目标加速度和速度估计方法

在线性调频连续波(LFMCW)雷达中,加速度运动目标回波存在多普勒频谱畸变现象,造成目标检测性能和参数估计精度损失。本文提出对同一距离单元上的多个目标的多普勒信号进行修正的多项相位变换,能够以较小的运算量,准确估计多个目标的速度和加速度,达到改善目标的检测性能和提高参数估计精度目的。     

基于多调频斜率单脉冲信号的多目标参数测量

对多目标的高精度参数测量是雷达面临的重要挑战。文中在分析线性调频信号距离-多普勒耦合效应的基础上,对传统的正负调频斜率脉冲信号实现单目标参数测量算法进行改进,提出一种利用多调频斜率合成脉冲信号实现多目标参数测量方法,解决了传统方法只能适用于单目标环境下的局限性,实现高精度多目标距离、速度测量,更好地抑制了虚假 目标的出现,有效解决了线性调频信号脉冲压缩带来的距离走动误差。仿真验证了该方法的有效性,且具有良好的测量精度和稳定的抗干扰性能。     

贪婪的量测划分机制下的多传感器多机动目标跟踪算法

针对低检测概率下多机动目标的跟踪问题,该文提出一种新的交互式多传感器多目标多伯努利滤波器(IMM-MS-MeMBer)。在IMM-MS-MeMBer滤波器的预测阶段,该文利用当前的量测信息自适应地更新目标的模型概率,并利用更新后的模型概率对目标状态进行混合预测;在IMM-MS-MeMBer滤波器的更新阶段,使用贪婪的多传感器量测划分策略对多传感器量测进行划分,并利用得到的量测划分集合和IMM-MS-MeMBer滤波器对目标的后验概率密度进行更新;除此之外,IMM-MS-MeMBer滤波器能够利用目标的角度和多普勒量测信息同时实现多个机动目标的位置、速度估计。数值实验验证了该文所提IMM-MS-MeMBer滤波器的优越性能。     

针对机动目标跟踪的雷达发射波形选择

该文首先在交互多模型(Interacting Multiple Model, IMM)算法的框架下,选择常速模型和自适应加速度模型作为状态模型,以应对实际中非合作目标的非机动与机动状态,并将此算法称为自适应IMM算法。然后针对机动目标跟踪时,雷达发射波形的选择需要兼顾测距测速性能与多普勒容忍性的问题,提出将V型调频(V-Linear Frequency Modulated, V-LFM)信号作为发射波形。通过分析多脉冲线性调频信号,V-LFM信号和M序列3种信号对目标距离和速度估计性能的克拉美罗下界(Cramer-Rao Lower Bound, CRLB)与多普勒容忍性表明,V-LFM信号可以在较少多普勒容忍性损失的情况下,有效提升对目标距离和速度的估计精度。仿真结果表明:发射多脉冲V-LFM信号并采用自适应IMM算法,可以明显提高雷达系统的跟踪性能。     

基于Kalman滤波的目标信号TOA测量校正

多点定位系统中,目标信号TOA测量精度直接决定了系统对目标的定位精度,而目标信号TOA测量精度取决于提供系统时钟的晶振的准确度和稳定度。针对多点定位系统中目标信号TOA测量准确度的具体问题,分析晶振频率偏移和GPS秒脉冲抖动对TOA测量准确度的影响,导出基于Kalman滤波的目标信号TOA测量校正方法。数值仿真证明此方法可以有效地改善目标信号TOA的测量准确度,对提高多点定位系统定位性能具有较强的现实意义与实用价值。     

调频步进雷达目标抽取算法及系统参数设计

伪峰、抽取损失和多普勒耦合时移是影响线性调频步进信号应用的重要问题.本文分析了传统目标抽取算法中静止伪峰和运动伪峰的产生机理,给出了避免这两种伪峰出现的条件.为了降低抽取损失,本文提出了基于距离像最大1范数搜索的移位抽取算法,该算法通过搜索在不同移位量下抽取后的目标距离像的最大1范数,确定最佳的移位量,并把该移位量对应的抽取结果作为最终的目标距离像,从而避免了运动伪峰和抽取损失,同时校正了距离像的多普勒耦合时移.文中进一步分析了搜索算法的应用条件,并给出了系统参数的设计方法.通过对点目标和延展目标的仿真,证明了该算法的可行性.     

距离多普勒域多雷达信号融合

传统的单雷达目标检测算法在低信杂噪比(SCNR)场景下,其检测性能较差,对低空微弱目标检测时,由于杂波信号很强,目标回波信号可能在单个雷达的回波中被杂波淹没,导致不能检测到目标。所以,文中提出一种多雷达信号融合算法检测动目标,在距离多普勒域对多个雷达回波信号进行融合,增强目标信杂噪比。最后,通过仿真来验证提出的算法的有效性。     

贪婪的量测划分机制下的多传感器多机动目标跟踪算法

针对低检测概率下多机动目标的跟踪问题,该文提出一种新的交互式多传感器多目标多伯努利滤波器(IMM-MS-MeMBer).在IMM-MS-MeMBer滤波器的预测阶段,该文利用当前的量测信息自适应地更新目标的模型概率,并利用更新后的模型概率对目标状态进行混合预测;在IMM-MS-MeMBer滤波器的更新阶段,使用贪婪的多传感器量测划分策略对多传感器量测进行划分,并利用得到的量测划分集合和IMM-MS-MeMBer滤波器对目标的后验概率密度进行更新;除此之外,IMM-MS-MeMBer滤波器能够利用目标的角度和多普勒量测信息同时实现多个机动目标的位置、速度估计.数值实验验证了该文所提IMM-MS-MeMBer滤波器的优越性能.     

基于多项相位变换的线性FMCW雷达目标加速度和速度估计方法

在线性调频连续波(LFMCW)雷达中,加速度运动目标回波存在多普勒频谱畸变现象,造成目标检测性能和参数估计精度损失.本文提出的方法首先将多普勒信号作多项相位变换,并在变换后的信号频谱中估计出目标的加速度,然后对多普勒信号进行加速度补偿,最后在补偿后的多普勒信号频谱中估计出目标速度.仿真分析表明这种方法能够以较小的运算量,达到改善加速度运动目标的检测性能和速度估计精度的目的.     

基于压缩感知的PD雷达序贯扩展卡尔曼滤波跟踪方法

提出一种新的基于压缩感知(Compressive Sensing, CS)处理的序贯扩展卡尔曼滤波(Sequential Extended Kalman Filter, SEKF)方法,以用于脉冲多普勒(Pulse Doppler, PD)雷达机动目标跟踪。利用目标在时延多普勒平面内的稀疏特点建立稀疏量测模型,然后通过压缩采样匹配重构方法获得目标的多普勒量测值,并用SEKF方法进行滤波更新,以改善目标状态的估计性能。在滤波过程中,应用CS处理可改善目标多普勒估计精度,而应用SEKF则可通过加入伪量测减小多普勒量测和目标运动状态之间的非线性误差。仿真实验结果表明,本文所提出的方法和传统的SEKF方法以及已有基于压缩感知的跟踪方法相比对机动目标有更好的跟踪性能。      

Asymptotic evaluation of the ambiguity functions of high-gain FM matched filter sonar systems

The evaluation of radar and active sonar matched filter ambiguity functions is critical to waveform choice, the proper selection of reference signals, and the ability to estimate system performance. In the radar case the evaluation is facilitated by use of the narrow-band approximation wherein Doppler distortion of the transmitted modulation function is neglected. However, modern-day sonar signals are usually broad-band with respect to the carrier frequency and long in duration so that the narrow-band approximation cannot be employed. This creates difficulties in both analytic and computer ambiguity function evaluations. Analytic difficulties arise from the inability to solve the appropriate integrals; computer difficulties, based on direct cross correlation, arise from the long computation time required. This paper shows how evaluation of the ambiguity functions of FM sonar signals having high time-bandwidth products can be greatly facilitated by asymptotic approximations derived on the basis of the principle of stationary phase. Application of the theory allows many seemingly difficult ambiguity evaluation problems involving highly complicated integrals to be solved rapidly using algebraic techniques. As examples of the theory, the cases of linear FM under constant target velocity conditions and hyperbolic (Doppler invariant) FM under constant target acceleration conditions are worked out. In addition, some interesting adjustable Doppler tolerant characteristics of a special modulation technique (parabolic FM) are described.     

Target Doppler estimation using wideband frequency modulatedsignals

The topic of this paper is the design and performance analysis of wideband sonar waveforms capable of estimating both target range and Doppler using as few replicas in the processing as possible. First, it is shown that for conventional Doppler sensitive waveforms, for which the Doppler and delay are uncoupled, the Doppler accuracy is proportional to the reciprocal of the signal duration. As a consequence, Doppler estimation requires a huge number of replicas if long duration signals are transmitted. Second, a design procedure for frequency-modulated signals with a required Doppler tolerance independent of signal duration is presented. Expressions for Doppler tolerance, Doppler and delay accuracy, and delay-Doppler ambiguity in case of high bandwidth duration product signals are derived. Finally, results are applied to low-frequency active sonar. Target range and Doppler have been accurately estimated from data collected during a sea trial in 1997     

Modeling the Effect of Human Body on TOA Based Indoor Human Tracking

In time-of-arrival (TOA) based indoor human tracking system, the human body mounted with the target sensor can cause non-line of sight (NLOS) scenario and result in significant ranging error. However, the previous studies on the behavior of indoor TOA ranging did not take the effects of human body into account. In this paper, measurement of TOA ranging error has been conducted in a typical indoor environment and sources of inaccuracy in TOA-based indoor localization have been analyzed. To quantitatively describe the TOA ranging error caused by human body, we introduce a statistical TOA ranging error model for body mounted sensors based on the measurement results. This model separates the ranging error into multipath error and NLOS error caused by the creeping wave phenomenon. Both multipath error and NLOS error are modeled as a Gaussian variable. The distribution of multipath error is only relative to the bandwidth of the system while the distribution of NLOS error is relative to the angle between human facing direction and the direction of transmitter–receiver, signal to noise ratio and bandwidth of the system, which clearly shows the effects of human body on TOA ranging.     

一种联合目标和外辐射源的无源跟踪模型

在海战场环境中,目标载辐射源(TS)常常辐射多种信号以实现通信、探测和导航等功能。然而,上述信号没有被传统的被动相干定位系统(PCLS)充分利用。文中提出了一种联合TS和外辐射源(IO)量测信息的无源跟踪模型,以TS提供的多普勒频差和IO 提供的到达时间(TOA)为目标联合观测量,提高了目标状态的估计精度。最后,以均方根误差(RMSE)为指标证明了模型的先进性。     

Estimation de la date d’arrivée d’un écho sonar et choix d’une référence des dates

Time estimation of echoes in sonar techniques requires a time origin. The instant of arrival is related to a peculiar wavefront of the incoming echo and defines the propagation delay between sonar and target. Delay estimation by cross-correlation techniques are biased due to Doppler effect. Such a bias is deeply related to the representation and the model used to describe the emitted signal and the echo. For finite energy signals it is shown that there is a peculiar wavefront called « uncoupling wavefront », such that the delay estimation is unbiased for any Doppler effect values. Such a result induces a new definition for Doppler tolerance.     

基于多普勒耦合估计的弹道目标测距方法

反导预警与空间监视雷达通常采用高频段、大脉宽探测远距离目标,此时距离多普勒耦合对于雷达精确测距有较大影响。同时,距离多普勒耦合的准确修正是稳定跟踪目标的必要条件,然而传统的处理方法不能适用于弹道目标等高机动目标的准确处理。本文提出了基于多普勒耦合估计的弹道目标高精度测距方法：首先采用旁路速度-加速度估计方法求解目标的径向速度,对目标测量距离进行距离多普勒耦合修正,再进行IMM-UKF滤波完成目标距离估计。该方法具有以下优势：利用当前帧的测量数据,同时考虑了目标径向加速度对于耦合的影响,提高了距离和速度的估计精度;相比跟踪时增加测速波形的方法,节约了雷达的资源,同时避免了速度测量与航迹误关联的问题;距离和速度的精确估计能够提升航迹关联成功率。仿真实验中与传统的距离多普勒耦合处理方法进行了比较,实验结果显示该方法大幅提高了雷达测距的精度。     

梳状谱信号多拷贝快速匹配/相关检测技术

在主动声纳信号波形中,梳状谱信号如调频脉冲传信号(PTFM)和正弦调频信号(SFM)等,因为其优良的抗混响以及速度分辨能力越来越受到人们的重视。然而,由于这类信号的多普勒容限很小,必须采用相当数量的拷贝才能够充分发挥其性能。常规的匹配/相关技术实现多拷贝检测需要的计算量过大,工程上实现难度极大,从而限制了它们在实际工程中的应用。本文充分利用梳状谱信号匹配/相关输出的多峰结构和Parseval定理,提出了一种新的梳状谱信号检测方法以及相应的多拷贝快速算法,并通过实际湖试数据对这种检测方法的正确性进行了验证。该算法同时实现了梳状谱信号匹配滤波/相关输出端多峰的能量累积,有利于检测器输出信噪比的提高以及声纳系统整体性能的改善。     

Lower bound on the achievable DSP performance for localizingstep-like continuous signals in noise

Estimating the time of arrival (TOA) of step-like signals (e.g., a rectangular pulse), which are, theoretically, of infinite bandwidth, is essential for many applications. In modern signal processing, the TOA estimator is implemented by digital signal processing (DSP) techniques. Existing tools for studying the TOA estimation performance do not take into consideration the estimation error caused by the finite sampling rate of the system. We present a new Cramer-Rao type lower bound that is used to evaluate the achievable performance of TOA estimation in a given processing sampling rate. We use it to refer to the important question of what processing sampling rate to use when localizing a step-like signal. We show that for a given signal-to-noise ratio (SNR), there exists a certain sampling rate threshold beyond which performance does not improve by increasing the sampling rate, and we show how to find it     

多路相差比对信号到达时间高精度测量技术

描述了一种通过多路数字相移和精确时钟相差比对实现对脉冲信号到达时间高精度测量的方法,其测量精度可以随多相时钟相位比对通道数的增加而进一步提高。实际测试表明,该方法可在不增加时间测量系统实时处理速率的情况下有效提高对信号到达时间的测量精度。