共查询到20条相似文献,搜索用时 15 毫秒
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For the realistic case where there is no secondary snapshot that does not contain the desired signal and exhibits the statistical characteristics similar to the snapshot under test, direct data domain (D3) beamforming approaches have been proposed to estimate a desired signal in the presence of interference. However, the basic idea of the D3 methods is realized by making significant sacrifices with respect to the number of degrees of freedom (DoFs). In this paper, we present a multi-snapshot approach for D3 beamforming. Using the least-squares method with multiple snapshots, we can eliminate the interference without causing a severe reduction in the number of DoFs. In addition, to consider a mismatch between nominal and actual target steering vectors, we propose a D3 approach combined with a probability constraint to prevent the self-nulling effect, and the relationship between the probability constraint and norm constraint is discovered. The simulations verify that the proposed method provides better performance and robustness than the conventional D3 approaches. 相似文献
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相干信号源自适应波束形成 总被引:1,自引:0,他引:1
介绍了常规自适应波束形成的一般理论,并在此基础上分析了期望信号与干扰信号相干时常规自适应波束形成失效原理,引入了空间平滑技术,给出了空间平滑技术去相干的原理和在自适应波束形成上的应用,同时给出了计算机仿真结果。 相似文献
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针对任意阵列天线的自适应空域滤波和低副瓣控制的问题,提出了一种连续自适应方向图控制方法。该方法通过采用线性约束最小方差准则的方向图综合算法( LCMV-PS)产生具有低副瓣特性的静态权矢量,利用该权矢量构造出新的约束条件,进行线性约束最小均方误差( LMS )自适应波束形成。该方法避免了常规的线性约束最小方差( LCMV)算法的矩阵求逆运算,计算复杂度低。对几种天线阵形的计算机仿真结果表明该方法收敛速度快,稳态性能良好。 相似文献
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This paper deals with the problem of robust adaptive array beamforming using signal cyclostationarity. The constrained cyclic adaptive beamforming (C-CAB) algorithm presented by Wu and Wong (1996) [6] has been shown to be effective in performing adaptive beamforming without requiring the direction vector or the waveform of the desired signal. However, this algorithm suffers from severe performance degradation even if there is a small mismatch in the cycle frequency of the desired signal. In this paper, we first evaluate the performance degradation of the C-CAB algorithm in the presence of cycle frequency error (CFE). A novel compensation method in conjunction with the subspace projection is then proposed to tackle the problem due to CFE. We reconstruct the required cyclic conjugate correlation matrix by using a compensation matrix to cope with the deterioration of its dominant singular value when CFE exists. Finally, several simulation examples are provided to show the effectiveness of the proposed algorithm. 相似文献
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大型线阵自适应数字波束形成超低副瓣技术 总被引:5,自引:0,他引:5
自适应数字波束形成技术是现代阵列天线系统必须采用的关键技术。为了对付强有源干扰,现代相控阵雷达都必须具有自适应的干扰抑制能力。除了对抗有源干扰外,大部分雷达还要求具有强杂波背景下检测目标的能力,这就需要雷达天线具有低或超低副瓣电平。本文针对大型线阵,结合数字波束形成,讨论了在保证自适应干扰置零的前提下,如何控制自适应波束的副瓣电平,从而实现阵列系统的超低副瓣性能。 相似文献
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An iterative approach to GSC beamforming is presented. The algorithm is able to achieve a GSC solution through a number of optimisation cycles, each of which includes several iterative weight vector updates. The algorithm is flexible and a weight vector may contain one or a few beamforming weights, implementing the optimal solution with reduced dimensionality. It is shown through theoretical analysis that the weight vector convergences with the proposed algorithm. The effectiveness of the algorithm is demonstrated through simulation results. 相似文献
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Laser heterodyne interferometer is one kind of nano-metrology systems which has been widely used in industry for high-accuracy displacement measurements. The accuracy of the nano-metrology systems based on the laser heterodyne interferometers can be effectively limited by the periodic nonlinearity. In this paper, we present the nonlinearity modeling of the nano-metrology interferometric system using some adaptive filters. The adaptive algorithms consist of the least mean squares (LMS), normalized least mean squares (NLMS), and recursive least squares (RLS). It is shown that the RLS algorithm can obtain optimal modeling parameters of nonlinearity. 相似文献
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实际应用中, 当假定的与真实的期望信号导向矢量之间存在一定误差时, 波束形成器的性能会急剧下降, 特别是当期望信号功率很强的时候.为解决这个问题, 提出了一种新的算法.当信源数小于阵元数时, 干扰加噪声协方差矩阵具有稀疏性.新方法首先利用该特性重构干扰加噪声协方差矩阵并由此得到与干扰导向矢量正交的子空间, 使接收的数据通过该子空间得到只含有期望信号和噪声的混合信号, 然后,对该混合信号基于最大化输出功率原理估计期望信号导向矢量, 最后,把得到的导向矢量和正交子空间来构造阵列加权值.仿真结果表明:该算法分别在假定的期望信号导向矢量存在误差、期望信号很强和低快拍数时仍然具有良好的性能. 相似文献
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由于临近空间复杂的大气环境,临近空间飞行器的测控通信系统与以往的卫星、导弹等系统测控有很大不同,针对低仰角测控通信所面临的多径反射干扰严重的问题,建立了系统的多径模型,提出了一种利用最大信干噪比准则进行测控通信的自适应盲波束形成算法,并进行了测控站固定和移动情况下算法性能的数值仿真,结果表明算法不仅具有很好的收敛性,并且权值的迭代能够使波束最大增益方向始终对准到期望方向 相似文献
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Jueping Cai Zan Li Xiaojun Chen Benjian Hao 《International Journal of Communication Systems》2011,24(6):745-760
In view of the characteristics of the meteor burst channel, the variable rate data transmission should be adopted to improve the system average throughput, which results in channel tracing and equalization problems at the receiver. Although the joint data and channel estimation of maximum likelihood sequence detection performing the principle of per‐survivor processing (PSP) is considered as an optimal detection scheme, its great computational complexity is a major problem and can hardly agree with the decreasing of the meteor channel. Based on the estimation of the system parameters, an adaptive state reduction of the PSP (ASRP) algorithm with only a few states in the trellis diagram is employed, while these states are chosen by the time‐varying threshold according to the exponential decay of meteor channels. It is shown that, ASRP can make a good tradeoff between the performance and the computational complexity, and provides reliable data transmission for adaptive modulation and coding of the meteor burst communication system. Computer simulation results and performance analysis are also included to support our developments. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
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A comparative study of two adaptive algorithms which are available for suppression of a narrow-band interference is discussed. Two Notch Filters (NF) are presented in this paper: (1) Conventional Least Mean Square Filter (LMS-NF) and (2) Function Elimination Filter (FEF-NF). These algorithms present two different forms of linear prediction procedures, both of which are based on the LMS criterion. The first approach (LMS-NF) concerns the well-understood linear prediction. According to the second approach (FEF-NF), part of the filter coefficients are fixed and do not require any adjustment.The major part of the paper is devoted to the quantitative analysis of the considered algorithms. This analysis is carried out by studying the change in the Signal-to-Interference Ratio and the Bit-to-Bit Power Ratio due to a change in an additive noise level and in a power of a sinusoidal interference. The nature of the considered filters and their performances are demonstrated through digital computer simulation. 相似文献
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Zoltn Katona Michael Grßlin Anton Donner Norman Kranich Hartmut Brandt Hermann Bischl Martin Brück 《International Journal of Satellite Communications and Networking》2020,38(3):301-313
From a geostationary Earth orbit (GEO) satellite's perspective, a low Earth orbit (LEO) satellite is visible on more than half of its orbit. Albeit the free‐space loss of an inter‐satellite link is much higher than the one of a direct ground link, considerable data rates and download volumes can be achieved. In this paper, we describe the system architecture of an integrated approach for a data relay satellite system and the development of LEO satellite and ground station modems. The approach allows serving several small and inexpensive LEO satellites at the same time both with low rate telemetry/telecommand links and with high rate download of sensor data. 相似文献
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This paper presents a novel reduced‐rank space–time adaptive processing (STAP) algorithm for interference suppression in global positioning system (GPS) receivers with low computational complexity for protection against the multipath and jamming interferences. The proposed STAP algorithm is based on the least‐squares (LS) criterion to jointly optimize a projection matrix, which is used for dimensionality reduction, and the reduced‐rank filter. The main novelties are the design of the projection matrix based on approximations of basis functions, the pattern matching between the projection matrix and the received data, and the derivation of a QR decomposition‐based reduced‐rank recursive LS algorithm for practical implementations. The proposed scheme works on an instantaneous basis, i.e. at each time instant, the most suitable pattern and the rank of the projection matrix are selected to reduce the dimensionality of the received data aiming at minimizing the squared error, while using an improved search algorithm to save the effort in finding the best projection matrix. Simulation results in a GPS system show that compared to existing reduced‐rank and full‐rank algorithms, the proposed algorithm has a much lower computational complexity, and remarkably better performance for interference suppression. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
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