Passive Localization Using Time Difference of Arrival and Frequency Difference of ArrivalWC

In order to improve the accuracy and engineering feasibility of four-Satellite localization system, the frequency difference measurement is introduced to the four-Satellite TDOA (Time Difference of Arrival) localization algorithm. The TDOA/FDOA (Frequency Difference of Arrival) localization algorithm is used to optimize the GDOP (geometric dilution of precision) of four-Satellite localization. The simulation results show that the absolute position measurement accuracy has little influence on TDOA/FDOA localization accuracy as compared with TDOA localization. Under the same conditions, TDOA/FDOA localization has better accuracy and its GDOP shows more uniform distribution in diamond configuration case. The localization accuracy of four-Satellite TDOA/FDOA is better than the localization accuracy of four-Satellite TDOA.

A PSO microseismic localization method based on group waves' time difference information

Aiming at the lower microseismic localization accuracy in underground shallow distributed burst point localization based on time difference of arriva（TDOA）,this paper presents a method for microseismic localization based on group waves’ time difference information Firstly, extract the time difference corresponding to direct P wavers dominant frequency by utilizing its propagation characteristics. Secondly, construct TDOA model with non-prediction velocity and identify objective function of particle swarm optimization （PSO）. Afterwards, construct the initial particle swarm by using time difference information Finally, search the localization results in optimal solution space. The results of experimental verification show that the microseismic localization method proposed in this paper effectively enhances the localization accuracy of microseismic explosion source with positioning error less than 50 cm, which can satisfy the localization requirements of shallow burst point and has definite value for engineering application in underground space positioning field.

Aviation multi-station collaborative detecting based on time-frequency correlation of data-link

As an important application research topic of the intelligent aviation multi-station, collaborative detecting must overcome the problem of scouting measurement with status of 'fragmentation', and the NP-hardness problem of matching association between target and measurement in the process of scouting to data-link, which has complicated technical architecture of network construction. In this paper, taking advantage of cooperation mechanism on signal level in the aviation multi-station sympathetic network, a method of obtaining target time difference of arrival (TDOA) measurement using multi-station collaborative detecting based on time-frequency association is proposed. The method can not only achieve matching between target and its measurement, but also obtain TDOA measurement by further evolutionary transaction through refreshing sequential pulse time of arrival (TOA) measurement matrix for matching and correlating. Simulation results show that the accuracy of TDOA measurement has significant superiority over TOA, and detection probability of false TDOA measurement introduced by noise and fake measurement can be reduced effectively.

Novel method for radial velocity difference estimation of moving targets with wideband signals

For the frequency difference of arrival （FDOA） esti-mation in passive location, this paper transforms the frequency difference estimation into the radial velocity difference estimation, which is difficult to achieve a high accuracy due to the mismatch between the sampling period and the pulse repetition interval. The proposed algorithm firstly estimates the point-in-time that each pulse arrives at two receivers accurately. Secondly two time of arrival （TOA） sequences are subtracted. And final y the radial ve-locity difference of a target relative to two stations with the least square method is estimated. This algorithm only needs accurate estimation of the time delay between pulses and is not influenced by parameters such as frequency and modulation mode. It avoids transmitting a large amount of data between two stations in real time. Simulation results corroborate that the performance is bet-ter than the arithmetic average of the Cramer-Rao lower bound （CRLB） for monopulse under suitable conditions.

High-Precision Time Delay Estimation Based on Closed-Form Offset Compensation

To improve the estimation accuracy,a novel time delay estimation(TDE)method based on the closed-form offset compensation is proposed.Firstly,we use the generalized cross-correlation with phase transform(GCC-PHAT)method to obtain the initial TDE.Secondly,a signal model using normalized cross spectrum is established,and the noise subspace is extracted by eigenvalue decomposition(EVD)of covariance matrix.Using the orthogonal relation between the steering vector and the noise subspace,the first-order Taylor expansion is carried out on the steering vector reconstructed by the initial TDE.Finally,the offsets are compensated via simple least squares(LS).Compared to other state-of-the-art methods,the proposed method significantly reduces the computational complexity and achieves better estimation performance.Experiments on both simulation and real-world data verify the efficiency of the proposed approach.

Performance Evaluation of Three-Dimensional UWB Real-Time Locating Auto-Positioning System for Fire Rescue

Fire rescue challenges and solutions have evolved from straightfor-ward plane rescue to encompass 3D space due to the rise of high-rise city buildings.Hence,this study facilitates a system with quick and simplified on-site launching and generates real-time location data,enabling fire rescuers to arrive at the intended spot faster and correctly for effective and precise rescue.Auto-positioning with step-by-step instructions is proposed when launching the locating system,while no extra measuring instrument like Total Station(TS)is needed.Real-time location tracking is provided via a 3D space real-time locating system(RTLS)constructed using Ultra-wide Bandwidth technology(UWB),which requires electromagnetic waves to pass through concrete walls.A hybrid weighted least squares with a time difference of arrival(WLS/TDOA)positioning method is proposed to address real path-tracking issues in 3D space and to meet RTLS requirements for quick computing in real-world applications.The 3D WLS/TDOA algorithm is theoretically constructed with the Cramer-Rao lower bound(CRLB).The computing complexity is reduced to the lower bound for embedded hardware to directly compute the time differential of the arriving signals using the time-to-digital converter(TDC).The results of the experiments show that the errors are controlled when the positioning algorithm is applied in various complicated situations to fulfill the requirements of engineering applications.The statistical analysis of the data reveals that the proposed UWB RTLS auto-positioning system can track target tags with an accuracy of 0.20 m.

基于免疫选择和自适应权重的鲸鱼优化定位算法

针对鲸鱼优化算法(WOA)在到达时间差和到达角度混合定位中存在后期迭代种群多样性减小,容易导致局部最优、定位精确度降低的问题,提出一种基于免疫选择和自适应权重的鲸鱼优化算法(IM-WOA).由最大似然估计法得到目标定位函数,为丰富种群多样性引入免疫机制,能够有效产生新的个体,从而避免种群陷入局部最优.通过将自适应惯性权重应用于个体位置的更新公式,实现算法全局探索能力和局部开发能力的平衡和协调,对经典基准函数和目标定位函数进行求解.结果表明,与WOA、AWOA、CSSOA、PIO、CASSA算法相比,IM-WOA算法对绝大多数基准函数的求解具有更高的精度、稳定性和定位精度.

基于改进Laplace小波时延提取的声源定位方法

针对侵彻弹命中多层硬目标后产生的撞击声的定位问题,提出了一种基于改进Laplace(refined Laplace,R-Laplace)小波时延提取的声源定位方法。该方法通过先验信息处理构造出Laplace小波,与声信号进行相关系数计算得到时延信息,并结合搜索匹配算法求得多次撞击的声源位置。搭建了声源采集定位系统,并进行多次硬目标撞击声试验。外场试验结果表明,可以定位出4层撞击的声源位置,定位误差平均为0.3 m。相较于传统基于到达时间差的定位算法定位精度较高。该算法在基于到达时间差声源定位问题中具有较大的应用潜力,对实际应用中的声源定位问题具有重要意义。

基于最优四基阵的被动式声源定位估计

针对现有被动式声源定位算法测量精度低、适用范围小等问题,提出了一种基于最优四基阵的被动式声源定位估计方法。该方法通过构建最优四基阵阵列结构以实现多阵元点共用,旨在使用较少的阵元总量实现对目标声源的融合定位估计,从而提高定位精度。并就该阵列模型确定空间目标定位方程组,将求解位置坐标问题转换为求解阵元点之间时延差值问题。进而采用二次分数低阶协方差算法求解脉冲噪声环境下的相应阵元间时延差值,即求得阵元信号的自分数低阶协方差和两阵元间信号的互分数低阶协方差之后,再次计算二者的互分数低阶协方差,以期更大程度上抑制脉冲噪声的影响,提高时延差值估计精度;最终将求得的时延估计信息带回定位方程组已实现对空间声源的定位估计。通过数值仿真和实测实验验证了所提方法的可行性及阵列结构的优越性。在实测实验中对声源定位估计误差仅为0.085 1 m,表明所提方法能较高精度的实现脉冲噪声环境下的声源定位,拓展了被动式声源定位算法的应用场景,具有一定的实际应用价值。

无需先验测量误差的定位节点选择方法

针对现有定位节点选择算法依赖先验测量误差的问题,研究了一种不依赖先验测量误差的时差与频差无源定位节点选择方法,该方法将两步加权最小二乘定位算法中目标估计误差协方差作为目标函数。在给定可用定位节点数目的情况下,通过引入一组布尔量构建关于目标函数为带约束的最小估计误差寻优问题,通过半定松弛技术将非凸问题转为半定规划问题进行求解,依据最小化问题特性,使得所提算法不依赖先验测量误差。仿真结果表明,不依赖测量误差的方法与穷举搜索法相比在定位性能上无太大差别;相比于穷尽搜索算法,所提方法复杂度低、实时性好。同时,仿真结果进一步表明在对运动目标定位过程中,及时调整定位节点组合的必要性。

适用于声源定位的气体绝缘输电线路超声导波传播特性研究

基于到达时间差(TDOA)的声源定位方法是当前气体绝缘输电线路(GIL)故障定位的主要方式,声波在GIL结构上的传输特性深刻影响着定位结果的准确性。为进一步提升故障定位精度,该文提出了考虑导波频散与多模态特性的GIL壳体声传输分析模型,以典型220 kV GIL管段为研究对象,建立声波传输有限元模型,研究了导波特性对故障定位的影响,确定了适用于故障定位的超声导波模态以及GIL非直管结构对该模态导波的衰减与时延量,通过现场定位试验验证了分析模型的可行性,为GIL声源故障定位系统的传感器配置与定位阈值设置提供了计算依据。结果表明,在20~60 kHz频带内,F(1,1)模态导波具有能量高、波形形状稳定、抗干扰能力强等特点,使用该模态导波进行故障定位精度较高。GIL非直管结构会对F(1,1)模态导波造成较大的幅值衰减与一定程度的时延,在故障定位中考虑非直管结构衰减与时延影响可以使定位误差降低60%以上。

基于广义互相关时延估计(TDOA)算法的声源定位跟踪系统设计与实现

为实现在二维平面内对声源进行实时定位和动态跟踪,运用时延估计(TDOA)互相关算法设计一种原声监听头阵列的CC-TDOA声源定位跟踪系统,实现对多个原声监听头进行同步采样,再进行信号放大及运算处理,运用LCD屏实时显示目标声源的距离和方位角度,同时运用二维云台控制激光笔对准声源,并持续动态跟踪声源。模拟仿真及真实环境实验测试表明,采用基于到达时间差的互相关定位算法,计算量小,精度较高,测试角度误差小于2o,距离误差小于1.2%,可以满足多种智能应用场合中声源实时定位与跟踪的要求。

基于频域阈值处理广义互相关和空间筛选的多源局部放电定位方法

该文针对电力设备的多源局部放电定位问题,提出了基于频域阈值处理广义互相关(frequency domain threshold processing generalized cross-correlation,FDTP-GCC)和空间筛选的多源局部放电定位方法。为实现多源局部放电超声信号的同源时间差提取问题,该文提出了FDTP-GCC算法,该算法直接应用于超声传感设备采集的原始信号,在频域内通过设置幅度谱阈值排除干扰频段,幅度谱归一化突出多源信号时间差的冲激函数特征,直接得到对应同源信号的时间差。通过仿真证明了FDTP-GCC算法进行时间差估计的高准确性、高稳定性、高抗噪能力。为解决FDTP-GCC算法带来的同源时间差分离的问题,该文提出了基于空间筛选的多源局部放电定位方法,并分析了采用基于解析解的算法和智能算法进行空间筛选的定位性能。最后采用双局部放电源进行了定位试验,试验结果表明该文方法提取的时间差误差均在1μs以内,两个局部放电源的定位误差为20.53cm和4.93cm。

一种改进组合加权的TDOA室内二维定位算法

针对现有组合加权算法对定位区域边缘的目标定位时精度较低的问题,在现有组合加权算法的基础上提出了一种改进算法。首先,将基站分组,以到达时差算法得到目标位置的多个估计结果;其次,计算各估计结果之间距离值并排序,以滑动窗口法判断是否存在基站组出现异常定位估计;最后,当任意基站组的定位结果发生异常时,使用目标位置估计结果及其估计克拉美罗下界值设计两个加权步骤的权值,通过二步组合加权算法得到最终定位结果。仿真结果表明,所提算法有效减少了原组合加权算法对定位区域边缘的目标定位时的误差,当测量噪声标准差为0.8 m时,所提算法相较于原算法在正方形边缘区域定位均方根误差减小了0.35 m;在定位狭窄矩形区域时,所提算法平均定位均方根误差减小了0.11 m。

主被动协同定位空能资源优化配置方法

无人机的快速发展为当今社会带来巨大便利,但其潜在的滥用现象对公共安全构成严重威胁,因此面向无人机的监测与定位技术近年来得到广泛研究。针对远距低飞无人机难以准确定位的应用问题,提出以无源为主、有源为辅的主被动协同定位框架,在基于到达时间差实现无源被动定位的基础上,引入支持往返到达时间测量的有源主动探测设备,择机对无人机进行主动式定位,补偿无源定位缺失的目标高程信息,从而提升无人机的三维定位精度。为充分挖掘主被动的协同定位潜力,文中深入探究无源被动定位节点预先部署的情况下,有源主动定位节点的空域和能域资源的配置方式,推导了主被动协同定位框架下的定位精度衡量指标,构建了空能资源联合优化问题,提出了基于非线性收敛因子和记忆指导的改进灰狼优化的空能资源优化算法。仿真结果表明,针对无人机定位时,主被动协同定位效果优于无源被动定位,典型场景下高程定位精度显著提升约96.33%。此外,所提的空能资源优化算法在求解空能资源联合优化问题时,性能优于标准(传统)灰狼算法、改进灰狼算法等。

基于银膜的自准直光纤法布里-珀罗腔设计及声源定位研究

提出一种基于银膜的自准直外腔式光纤法布里-珀罗(EFPI)干涉仪声传感器阵列,用于中低频声信号的检测以及二维平面声源定位。传感器阵列由三个相同结构的EFPI组成,结构简单、制作简便。银膜的应用和准直器的引入提高了传感器的声压灵敏度,扩大了声源定位范围。实验结果表明:单个传感器声压灵敏度为185 mV/Pa,最小可探测声压为52.7μPa/Hz^(1/2)@500 Hz。在声源指向性实验中,声源设置在传感器正前方时,其声压灵敏度达到185 mV/Pa,声源设置在传感器侧面(90°,270°)时,其声压灵敏度衰减仅为4.5%。传感器阵列结合到达时间差技术,成功实现高精度的声源定位,系统的理论空间分辨率为0.71 cm,最大定位误差不超过2.8 cm,定位范围为200 cm×200 cm,具有成本低、实用性高等优点。

Three-Dimensional Sound Source Location Algorithm for Subsea Leakage Using Hydrophone

Leakages from subsea oil and gas equipment cause substantial economic losses and damage to marine ecosystem,so it is essential to locate the source of the leak.However,due to the complexity and variability of the marine environment,the signals collected by hydrophone contain a variety of noises,which makes it challenging to extract useful signals for localization.To solve this problem,a hydrophone denoising algorithm is proposed based on variational modal decomposition(VMD)with grey wolf optimization.First,the average envelope entropy is used as the fitness function of the grey wolf optimizer to find the optimal solution for the parameters K andα.Afterward,the VMD algorithm decomposes the original signal parameters to obtain the intrinsic mode functions(IMFs).Subsequently,the number of interrelationships between each IMF and the original signal was calculated,the threshold value was set,and the noise signal was removed to calculate the time difference using the valid signal obtained by reconstruction.Finally,the arrival time difference is used to locate the origin of the leak.The localization accuracy of the method in finding leaks is investigated experimentally by constructing a simulated leak test rig,and the effectiveness and feasibility of the method are verified.

多麦克风阵列数据融合声源定位方法研究

针对TDOA估计精度受采样频率限制的问题以及单一麦克风阵列声源定位误差较大的问题,提出了两种改进方法并进行了仿真验证。首先,为了解决采样频率低导致的TDOA估计误差较大的问题,提出了一种基于三次样条插值的改进二次互相关算法进行TDOA估计的方法,在第1次互相关后进行三次样条插值提高采样频率,之后进行第2次互相关求得TDOA。在10倍插值的条件下仿真表明该方法将TDOA误差从7.6%降低到0.6%,有效的提升了估计精度。其次,为了解决单个麦克风阵列声源定位误差较大的问题提出了一种多麦克风阵列数据融合的声源定位方法,以四元十字麦克风阵列为单元,首先在每个单元阵列上进行单独的声源定位,之后将多个单元阵列的定位结果进行融合得到最终的声源位置,选取空间中的10个点利用双麦克风阵列以及四麦克风阵列对比单麦克风阵列进行远场定位仿真,结果表明,单麦克风阵列在声源距离较远时的定位误差达1 m以上,而利用所提方法设计的双麦克风阵列的定位距离误差在0.3 m以下,四麦克风阵列的定位距离误差在0.2 m以下,大大提高了声源定位的精度。

未知信号传播速度的TDOA定位方法研究

研究了未知信号传播速度时的到达时间差(Time-Difference-Of-Arrival,TDOA)定位问题,提出两种联合估计信号传播速度和目标位置的定位方法。第一种方法为两步加权最小二乘方法。在该方法中,首先不考虑变量之间关系,得到一个关于未知变量的初始加权最小二乘估计。为改进第一步估计的性能,第二步考虑第一步估计中变量之间的关系,将其转换为一个标准的广义信赖域子问题,最终获得更高精度的估计性能。第二种方法为半正定松弛方法,通过构建非线性非凸加权最小二乘问题,然后利用半正定松弛技术将其松弛为凸的半正定规划问题,容易求解。仿真结果表明,所提两种方法均能够在高斯噪声下,且噪声不太大时达到克拉美-罗界。

基于等效地球半径的超短波超视距时差定位方法

超视距无线传输条件下的超短波辐射源目标高精度定位技术是非合作通信侦测中亟待解决的难点问题;针对该难题,在考虑地球曲率影响的同时,提出采用等效地球半径模型对超短波信号的对流层散射信道进行修正,在此基础上构建全新的基于到达时间差的定位方程组;通过Chan算法与牛顿迭代法相结合,对该非线性方程组进行求解,从而实现了辐射源目标空间位置的获取;详细推导了不同坐标系下坐标的转换计算、TDOA方程组的求解算法、定位性能的客观评价参数——几何精度因子;通过仿真分析了时差测量精度对定位精度的影响,并对提出的等效地球半径模型进行了仿真验证;结果表明,该模型可以有效降低超视距定位误差,并且随着距离的增加,定位性能的提升效果更明显,实现了对超短波超视距辐射源目标的高精度定位,具有较高的工程应用价值。