DESIGN OF VIRTUAL UNIFORM LINEAR ARRAYS FOR EFFICIENT DIRECTION FINDING

The problem considered in this paper is to interpolate a virtual uniform array froma real two-dimensional array with arbitrary geometry via an interpolation matrix. The key to thisproblem is how to arrange these virtual sensors. It is shown that the virtual uniform linear arrayshould have the same main-lobe beam-pattern as the real array over an angular sector of interest.Simulation results are presented to illustrate the application of virtual array in direction finding.     

基于双L型阵的二维测向算法

提出了一种基于双L型阵的二维测向算法。通过定义新的三维波达方向角,同时利用旋转不变算法获得每一维入射角的独立估计,再由波达方向角之间的约束关系进行配对,提高了测向精度与二维角成功配对概率,改善了双L阵二维测向精度对来波方向敏感的问题。计算机仿真结果表明:所提算法在观测的区域内均具有较高测向精度,特别是在仰角较小时较传统算法其测向精度有较大提高,在低信噪比情况下与传统算法比较提高了二维测向中的角度配对成功概率。     

High-resolution direction finding: the missing data case

This paper considers the problem of estimating the direction-of-arrival (DOA) of one or more signals using an array of sensors, where some of the sensors fail to work before the measurement is completed. Methods for estimating the array output covariance matrix are discussed. In particular, the maximum-likelihood (ML) estimate of this covariance matrix and its asymptotic accuracy are derived and discussed. Different covariance matrix estimates are used for DOA estimation together with the MUSIC algorithm and with a covariance matching technique. In contrast to MUSIC, the covariance matching technique can utilize information on the estimation accuracy of the array covariance matrix, and it is demonstrated that this yields a significant performance gain     

High resolution wideband direction finding arrays based on optimumsymmetrical number system encoding

A new interferometer direction finding (DF) array architecture based on the optimum symmetrical number system (OSNS) is presented. OSNS arrays are capable of unambiguous high resolution DF over a wide bandwidth and field of view with as few as three elements, with multiple baseline options. A three element array was designed, fabricated and tested at 8.5 GHz to verify the OSNS concepts experimentally     

Direction finding with time-varying arrays

This paper considers the problem of finding the directions of narrowband signals using a time-varying array, whose elements move during the observation interval in an arbitrary but known way. Assuming a Gaussian signal model, we derive the Cramer-Rao bound (CRB) and the maximum likelihood estimator for the directions of arrival. The single source case is studied in detail. Time-varying arrays are shown to be more robust to ambiguity errors than static arrays of comparable dimensions     

High-accuracy direction finding in multipath environment with short-wave antenna arrays comprising a small number of elements

A method for short-wave multipath direction finding is considered. The method allows high-accuracy determination of the directions of arrival and the amplitudes of a priori unknown arriving signals through the use of an antenna array comprising a small number of independent receiving elements with narrow-bandwidth filters placed at their inputs. An algorithm based on eigenvector decomposition of the correlation matrix of the complex signals arriving at the inputs of the radiating elements in each subband; separation of the eigenvectors into signal vectors and noise vectors; determination of the receiving-antenna eigenpatterns from the obtained vectors; and substantiation of the functional equation that allows, with the antenna eigenpatterns taken into account, the signals’ amplitudes and angles of arrival of the signals to be determined, is proposed. The results of a numerical simulation, which confirm the high accuracy of direction finding by the proposed method, are presented.     

Performance of radial-basis function networks for direction ofarrival estimation with antenna arrays

The problem of direction of arrival (DOA) estimation of mobile users using linear antenna arrays is addressed. To reduce the computational complexity of superresolution algorithms, e.g. multiple signal classification (MUSIC), the DOA problem is approached as a mapping which can be modeled using a suitable artificial neural network trained with input output pairs. This paper discusses the application of a three-layer radial-basis function neural network (RBFNN), which can learn multiple source-direction findings of a six-element array. The network weights are modified using the normalized cumulative delta rule. The performance of this network is compared to that of the MUSIC algorithm for both uncorrelated and correlated signals. It is also shown that the RBFNN substantially reduced the CPU time for the DOA estimation computations     

Uni-vector-sensor direction finding with regularized ESPRIT

The regularized Least-Squares Estimation method of Signal Parameters via Rotational Invariance Techniques （LS-ESPRIT） is herein proposed for Direction-Of-Arrival （DOA） estimation of non-Gaussian sources with only one acoustic vector-sensor. The Second-Order Statistics （SOS） and Higher-Order Statistics （HOS） of data are fused within a regularization framework. The steering vectors can be blindly identified by the regularized ESPRIT, from which the aim of DOA estimation can be achieved. Several variants of the regularized ESPRIT are discussed. A suboptimal scheme for determination of the regularization parameters is also given.     

Errors of target direction finding by radars with planar arrays under the influence of external noise radiations

This paper describes the mathematical model, which allows to investigate both fluctuation and systematic errors of target angular coordinates measurement in a radar with planar phased antenna array under the influence of external sources of noise radiations. The results of mathematical simulations are presented.     

无线电测向的误差分析及对策

在实际应用中，许多因素会使测向结果与真实值产生偏差。深入了解造成测向误差的各种原因，对于使用测向设备去工作的技术人员来说也许更有实际意义。测向误差的产生，大体可归纳为三个方面的原因：本机误差、传播环境或信号调制造成误差、人为因素造成误差。 一、本机误差 本机误差是指由于测向系统本身的缺陷而产生的示向度误差。 １、天线孔径对误差的影响 我们用天线阵孔径Ｄ与信号波长入之比来描述天线孔径对测向误差的影响。以２单元干涉仪测向体制为例，我们发现测向系统天线阵孔径不同对具有相同的相位同步误差信号进行测向时，其测…     

Performance analysis of spatial smoothing with interpolated arrays

The interpolated spatial smoothing algorithm is a computationally efficient method for estimating the directions of arrival (DOAs) of signals, some of which may be perfectly correlated. It extends the spatial smoothing method to arbitrary array geometries. A statistical performance analysis of the algorithm is presented. Closed-form expressions for the covariance matrix of the DOA estimation errors are derived using a perturbation analysis. Evaluating these expressions for specific cases and comparing them to the Cramer-Rao lower bound for the DOA estimates provides insight into the statistical efficiency of this algorithm. The formulas for the error covariance are quite general and can be specialized to provide results for other DOA estimation algorithms as well     

基于典范相关分析的时差测向技术研究

测向是电子战系统的一个重要组成部分,测向精度直接对信号分选、识别、定位、干扰决策等都产生较大的影响.时差测向的准确度和灵敏度都相对较高,在无源测向中具有广阔的应用前景.针对时差测向抗干扰性能差和噪声影响的问题,本文提出采用典范相关分析方法改进其性能,并对这种新的测向算法进行了完整的分析.通过仿真实验,可以看到本文提出的基于典范相关分析的时差测向方法能够取得比常规时差测向更稳定、准确的结果,而且实现简单,实时性好,能充分满足电子战系统实时性的要求.     

Preprocessing for direction finding with minimal variancedegradation

Numerous authors have advocated the use of preprocessing in high-resolution direction of arrival (DOA) algorithms. The benefits cited include reduced computation, improved performance in spatially colored noise, and enhanced resolution. The authors identify the preprocessing matrices that provide minimum variance estimates of DOA for a number of models and algorithms. They examine the Cramer-Rao bound (CRB) for Gaussian signals, the CRB for deterministic signals, and the asymptotic variance of the MUSIC estimator for preprocessed data. They also study the effect of array manifold errors on the direction estimates. As expected, the optimal preprocessor requires knowledge of the source directions. However, they show that performance that is close to optimal can be obtained with only approximate knowledge of the source directions (with an error not exceeding the array beamwidth) if the design rules outlined in this paper are used     

Direction finding of coherent sources with nonlinear arrays

This paper presents an approach to estimate the directions-of-arrival (DOAs) of narrowband coherent (completely corrected) signals by an arbitrary geometry sensor array. The concept of focussing matrices is introduced to estimate the outputs of a virtual uniform linear array from the outputs of the real array in order to use spatial smoothing techniques. Unlike the work presented in [5], the proposed approach avoids multiple singular value decomposition (SVD) computations in the various sectors because it is not necessary to divide the field of view of the array into sectors. Simulation results are given to support the approach.On leave from the Department of Electrical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, People's Republic of China.     

基于谐波特征分析的时间调制阵列测向研究进展

针对近年来发展起来的基于谐波特征分析的时间调制阵列(time modulated array,TMA)测向这一新型无线电测向技术体制,全面总结了其目前的发展现状以及与传统阵列测向体制相比较的优缺点.首先分析了TMA的起源、发展与数学基础;其次总结了基于TMA的测向方法的研究现状;然后对二单元TMA测向、多单元TMA测向...     

基于信息典型相关分析的时差测向

测向是电子战系统的一个重要组成部分,测向精度直接对信号分选、识别、定位、干扰决策等都产生较大的影响。时差测向的准确度和灵敏度都相对较高,在无源测向中具有广阔的应用前景。针对时差测向抗干扰性能差和噪声影响的问题,首先提出了一种基于信息典型相关分析的盲源分离算法,在辐射源信号先验信息未知时分离天线阵接收的混合信号;然后将分离后的信号进行相关分析获得时差的估计,用以改进时差估计和测向性能,并对这种新的测向算法进行了分析。仿真实验表明,基于信息典范相关分析盲源分离算法的时差测向能够取得比常规时差测向更稳定、准确的结果。      

Monostatic multi-source direction finding based on I/Q radio frequency data

At present, many researchers study methods for estimating signal sources through direction finding. The use of phase interferometry for directional applications is common. This method measures the phase through the phase-locked loop module, and the detection bandwidth is limited. We propose to extract the phase information of signals from the I/Q data by electromagnetic measurement. In this paper, One-dimensional phase interferometer is expanded to two-dimensional antenna array. Use the equilateral triangle antenna array to increase the spatial dimension of the direction finding antenna array, and to avoid the phase ambiguity. Through the calculation of associated phase difference to achieve all-directional angle detection. The angle incidence of multi-signal estimation method in single station is proposed in this work. The estimated phase difference is converted into the calculated the duty cycle of the phase waveform. The experiment result show that the method based on the I/Q data can quickly achieve multi-signal source direction finding.     

Wave propagation and coupling in linear arrays with application to the analysis of large arrays

Waves inside linear arrays are analyzed for the case of single-port excitation. A frequency-domain method is proposed for the extraction of the amplitude decay and phase velocity of the waves, based on simulation results obtained for terminal excitation at one end and near the middle of the array. The waves reflected by the array ends are also extracted, under a single-reflection assumption. This model is then exploited for estimating the port currents when other elements of the array are excited, as well as for larger arrays. Simulation results are shown for port currents and element patterns in arrays of broad-plate dipoles.     

磁偏角影响无线电测向结果的技术分析

从无线电测向的角度出发,介绍磁偏角的定义、补偿方式以及修正方法。通过理论分析和软件仿真论证磁偏角对短波、超短波干扰定位的影响。经验证,磁偏角的精确度直接关系到测向定位结果的准确度。