共查询到17条相似文献,搜索用时 62 毫秒
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射频干扰(RFI)会污染合成孔径雷达(SAR)回波信号,增加SAR图像解译难度。脉冲式直达波干扰(PDWI)作为典型的RFI,在原始回波域以明亮条纹状掩盖SAR回波信息,对SAR成像质量产生严重影响。现有的干扰抑制方法中,传统的特征子空间投影(ESP)方法对整条含干扰脉冲进行干扰抑制,造成了脉冲中非干扰位置有用信号损失。为了保护有用信号,该文提出一种改进ESP的SAR脉冲式直达波干扰抑制方法。首先,通过两次检测干扰,获取PDWI在时域中的具体位置。其次,仅对检测的干扰位置数据,采用ESP将有用信号和干扰信号分离。最后,从原始数据中减去ESP重构的干扰数据以实现干扰抑制。仿真和实测数据处理表明,与现有方法相比,该方法能够有效避免SAR原始数据中有用信号的损失,抑制了脉冲式直达波干扰。 相似文献
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电磁环境日益恶劣且到达接收机的导航信号非常微弱,导航接收机的输出性能受干扰影响非常明显,因此在干扰背景下提高导航接收机的输出性能是十分重要的。阵列信号处理中的传统抗干扰方法包括采样协方差矩阵求逆 SMI(Sample Matrix Inverse)方法、最小均方误差 LMS(Least Mean Square)迭代方法、功率倒置 PI(Power Inverse)算法等,这些方法具有较高的抗干扰性能,但抗干扰后对信号增强没有效果。本文在子空间投影抗干扰方法的基础上,结合导航信号相关性特点,对子空间投影后信号进行运算,构造最优相关峰矢量,利用该矢量进行波束合成,实现导航信号增强的目的。对实测数据处理可知,该方法可以有效提高抗干扰后导航信号强度。 相似文献
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考虑实际的MC-CDMA上行链路,深入研究了基于RLS算法实现的MOE(RLS-MOE)盲自适应多用户检测,提出了MC-CDMA系统下一种基于子空间约束RLS的半盲多用户检测算法.在MOE盲多用户检测的基础上,利用小区内用户的已知扩频码设计了一种MOE半盲多用户检测器.将子空间方法和RLS算法相结合提出一种基于子空间约束的RLS 算法,使用该算法自适应得到MOE的权向量.本文算法利用所有已知用户的扩频码抑制了小区内用户的干扰,子空间约束的RLS 算法降低了噪声的影响,从而改善了系统的性能.修正的PASTd算法实现了信号的自适应跟踪,大大降低了计算量.仿真实验表明,本文算法的输出信干噪比和误码率性能优于RLS-MOE盲多用户检测,更接近于最优值. 相似文献
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In this paper, we address the problem of interference cancellation in global positioning system (GPS) receiver using a two-step approach: subspace projection technique and maximum signal-to-noise ratio (MSNR) beamforming. The interference signals can be effectively suppressed by projecting the received signal on the noise subspace. Here noise subspace tracking algorithm is employed to estimate the noise subspace directly. We then apply a beamformer to maximize the signal-to-noise ratio of the interference-free signal. Simulation results show that our approach can effectively eliminate the strong interference and enhance the performance of the GPS receiver. 相似文献
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Suk‐seung Hwang John J. Shynk 《International Journal of Satellite Communications and Networking》2011,29(4):315-332
The Global Positioning System (GPS) utilizes low‐power spread‐spectrum signals and thus is vulnerable to various types of high‐power interference sources. It requires at least four satellites for estimating three‐dimensional user positions and the receiver clock bias. In this paper, we propose a blind adaptive GPS receiver that is based on a new despreader and the one‐stage constant modulus (CM) array. The despreader consists of a conventional GPS despreader and a so‐called null despreader, which together modify the received signal so that the CM array can extract the GPS signal of interest. The beamformer not only rejects jammers and extracts the GPS signal of interest without explicit direction‐of‐arrival (DOA) information of any of the signals but also it has a low computational complexity compared with conventional techniques, such as minimum‐variance distortionless‐response (MVDR) beamforming. As a conventional despreader can recover only one GPS signal, multiple despreaders are usually required for separating multiple GPS signals. We also explore an extension of the proposed null despreader to detect multiple GPS signals. Computer simulation examples are presented to illustrate the performance of the receiver for different types of jammer signals. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
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Combined spatial and time-frequency signatures of signal arrivals at a multisensor array are used for nonstationary interference suppression in direct-sequence spread-spectrum (DS/SS) communications. With random PN spreading code and deterministic nonstationary interferers, the use of antenna arrays offers increased DS/SS signal dimensionality relative to the interferers. Interference mitigation through a spatio-temporal subspace projection technique leads to reduced DS/SS signal distortion and improved performance over the case of a single antenna receiver. The angular separation between the interference and desired signals is shown to play a fundamental role in trading off the contribution of the spatial and time-frequency signatures to the interference mitigation process. The expressions of the receiver signal-to-interference-noise ratio (SINR) implementing subspace projections are derived, and numerical results are provided 相似文献
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The performance of multiple signal classification(MUSIC) algorithm with regard to solving closely spaced direction of arrivals(DOAs) depends strongly upon the signal-to-noise ratio(SNR) and snapshots.In order to solve this problem,a method by reconstructing the spatial spectrum function with both noise subspace and signal subspace is presented in this paper.The key idea is to apply the full information contained in covariance matrix and change the projection weights of steering vector on the noise and signal subspace by their revised eigenvalues,respectively.Comparing with the MUSIC algorithm,it does not increase any computational complexity either,and remarkably,it has the advantages of simultaneously reducing noise and keeping the high-resolution ability under low SNR and small sample sized scenarios.Simulation and experiment results are included to demonstrate the superior performance of the proposed algorithm. 相似文献