Single-snapshot robust direction finding

The paper presents a novel approach for recursively estimating the directions of arrival of incident signals as measurements are received along a sensor array. Using a single snapshot and without any statistical assumptions, the proposed method employs a robust performance criterion, which is based on worst-case gain minimization. The criterion aims to reduce the estimation error induced by worst-case amplitude and phase perturbations as well as additive noise in the array model. An algorithm that guarantees the criterion-within a first-order approximation-is developed and shown to converge. Moreover, instead of using a trial-and-error method to find a constant, minimum worst-case gain, the minimum worst-case gain is updated as each sensor measurement is processed. A step-by-step implementation of the algorithm is presented, and its computational complexity is analyzed. The performance of the new approach is evaluated by simulating the estimation algorithm for a linear array and comparing its performance with that of an existing single-snapshot algorithm.     

An adaptive tracking algorithm for direction finding and array shape estimation in a nonstationary environment

This paper presents an adaptive tracking algorithm for the subspace-based direction of arrival estimation of multiple sources in a nonstationary, environment. The nonstationarities are due to moving sources or to timevarying distortions of the sensor array shape. The proposed algorithm relies on the properties of a linear operator, referred to as the Propagator, which only exploits the linear independency of the source steering vectors. The Propagator allows not only the calibration of the array shape, but also the determination of the source and the noise subspaces without any eigendecomposition of the cross-spectral matrix of the received signals. A gradientbased adaptive algorithm is here proposed for the on-line estimation of the Propagator. A theoretical analysis of the behaviour of this algorithm in a nonstationary environment is given. Simulations are carried out in the case of moving sources and in the case of a time-varying array shape. They exhibit the good performances of the proposed algorithm.     

无线电监测测向常用名词术语

(接上期)28固定监测台(站)具有监听、测向、测量、分析、记录功能的不可移动的综合性台(站)。29半固定监测台(站)具有监听、测向、测量、分析、记录功能的可移动的综合性台(站)。     

无线电监测测向常用名词术语

对于参考点（测向机所在地）而言，目标所在地理方向的极座标角度数。两点之间方位角度数按下述方法确定：异地A、BN点。A为参考点（测向机所在地）．B为目标地，B点相对于A点的方位角是：从过A点的子午线（“零”度方向）起算，顺时针旋转到A至B的大圆路连线的极座标的角度数。B点相对A点的方位角度数有唯一性。见上期图（101）。[第一段]     

多任务监测、测向系统

随着无线电监测、测向技术的发展,多任务无线电监测、测向体系日益重要.介绍了多任务体系在无线电管理中的应用,以及系统构成优缺点.     

测向定位技术准确度及误差校正

测向定位技术是无线电管理的一个重要课题。测向定位过程中的误差的种类和产生的原因很多。选择适当的方法对误差进行校正，可以有效的减小测向误差带来的损失，提高无线电管理的效率。     

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.     

Focusing filters for wide-band direction finding

A time-domain equivalent of the coherent signal-subspace transformations (CST) is established for wideband direction finding in a possible multipath environment using general arrays. Time-domain equivalents of focusing are derived based on the least squared error approach for general transformations, and the Taylor series expansion approach for closed-form transformations. The preprocessor is realized by a multichannel digital finite impulse response filter. For diagonal transformations, the problem reduces to implementing different delays at each sensor, which in turn leads to computational simplicity. Various tapped delay line filters for realizing an arbitrary delay are proposed and compared. Simulation results reveal that low-order filter structures in the time domain achieve similar performance to the frequency domain approach, even at detection and resolution thresholds     

不容忽视的细节

在我省举行的无线电测向比赛中,我站在进行广播电台的测向定位时成绩不佳,定位误差大,令大家感到非常意外. 赛后,我们对比赛成绩不佳的原因作了分析,发现我们在比赛时的第一测试点获得的示向度196°比实际的示向度小了10°,从而导致了二线交叉定位时,与实际目标点偏差较大.然而由于比赛已经不能重复,进一步的原因无法真正确定.但大家都知道无线电测向、定位的过程,是一项复杂而细致的工作,任何细节的忽视,都可能直接导致测向结果出现偏差.下面就结合这次比赛以及平时训练的体会,把在测向中容易忽视的细节作个探讨,供读者参考.     

Fast orthogonal search for direction finding

An efficient modelling algorithm known as fast orthogonal search (FOS) is applied to the estimation of the directions of plane waves incident on an array of sensors. An iterative approach which decreases the mean-squared error of the original FOS model is introduced. The methods are demonstrated and compared with Root-MUSIC in computer simulations.<>     

Low-complexity method for HF direction finding

A new algorithm is presented with low complexity for HF (3-30 MHz) direction finding. This method is applied to different types of signal and to different configurations of circular arrays (homogeneous or heterogeneous)     

基于GPS的红外成像测向交叉定位方法

开展基于GPS的红外成像测向交叉定位研究,引入GPS技术进行测站定位、确定目标测向基准,以地理投影坐标系为定位坐标系,建立双站交叉定位、测站定位、目标测向数学模型;分析定位误差与布站情况、GPS定位精度、测角精度的关系;提出基于SolidWorks的仿真试验方法,验证了本文双站交叉定位数学模型的正确性;设计两组外场验证试验,全面验证了本文定位方法的有效性。试验表明,本文方法对近1km远处目标的定位误差<0.5m,不要求测站相互可见,且便于描述目标偏离测站、其他任意GPS已知点的地理方位角,具有重要应用价值。     

共轭传播算子测向算法

针对一维信号提出了共轭传播算子测向算法(COP),新算法利用了阵列输出数据的共轭,通过对阵列孔径的扩展,可对多于阵元数的信号进行测向,其分辨力和测角精度优于OPM(正交传播算子测向算法)和MUSIC 算法.分析了新算法的均方误差性能和计算复杂度,得到了均方误差的解析表达式.仿真实验验证了COP算法的优良性能,均方误差的理论值与仿真值相符.     

Adaptive methods for signal detection and direction finding

Adaptive methods for signal detection and direction finding are considered in the framework of the maximum likelihood method. The possibility of application of adaptive methods for solution of the problem of coherent passive radar is shown.     

Eigenvector matrix partition and radio direction finding performance

The problem of high frequency radio direction finding (HFDF) is solved, using eigenstructure analysis of the spatial correlation matrix. The general approach is to compute a matrix of eigenvectors which are ordered according to decreasing eigenvalues. The eigenvector matrix is partitioned so that one part is associated with signals and the other is associated with noise. The performance of a direction finder is investigated under the conditions of an incorrectly partitioned eigenvector matrix. In particular, observations are presented for various conditions of 1) signal coherence, 2) bearing separation, 3) unequal signal strength and 4) additive noise. It is noted that underestimation of signal order produces biasing and spurious spectral peaks. In the high signal-to-noise ratio (SNR) case it appears that overestimation of signal order is a desirable strategy. In the low SNR case the estimation of signal order is extremely critical. The effect of the noise is to merge the eigenvalues so that separation of signal and noise components, based on size of the eigenvalues, is difficult to do reliably.     

无线电测向技术(一)

在建设无线电监测和测向系统时，选括合适的站点位置是保障系统性能的先决条件之一。而测向机的选择对于在不同的地貌环境中建设监测测向系统具有重要的意义。     

Hybrid digital-analog technique for UWB direction finding

In this letter, we propose an alternative approach for UWB direction finding using hybrid digital-analog technique. The proposed system uses an array of leading-edge pulse detection scheme in analog domain. The detection scheme is realized using tunnel diode with envelope detector and comparator latch, whose output is digital binary signal. The outputs or all array branches are then summed up to form a staircase-shaped waveform, whereby the slope of the waveform indicates the direction of impinging UWB signal. In order to detect the slope and produce the estimation of the direction, an analog differentiator joint with a peak detector is utilized. The proposed system is relatively simple and does not require high sampling rate or high speed DAC.     

无测向能定位吗?

众所周知,测向设备造价昂贵,相比之下,监测接收机费用则低廉.同时,在监测站的实际工作中,测向系统的使用率较低,测向功能仅在定位未知电台(干扰源)或监测已知电台是否变更台址时使用;其他诸如针对无线信号的频谱分析、统计分析等,均与测向系统无关.问题是,能否使用监测系统而非测向设备来完成定位?本人认为,在一定的条件下是可行的.     

空间谱测向技术简介——多波测向

简要介绍多波测向技术原理、多波测向算法的分类以及非线性空间谱估计（多信号分类法,MUSIC）的概念。