共查询到20条相似文献,搜索用时 15 毫秒
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针对瞬态干扰严重影响天波超视距雷达(OTHR)目标检测性能的问题,提出了一种基于小波影响锥的瞬态干扰抑制方法。该方法利用一维离散平稳小波变换确定信号的奇异点(瞬态干扰),然后将每一奇异点对应的影响锥内的小波细节系数置零,最后通过一维逆离散平稳小波变换重构数据。该方法避免了杂波抑制和插值重构,运算量小,实用性强。对天波雷达实测数据的处理实验表明:提出的方法是有效的。 相似文献
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针对欠密度流星余迹干扰影响天波超视距雷达目标检测的问题,提出了基于总体最小二乘旋转不变估计信号参数(Total Least Squares-Estimating Signal Parameter via Rotational Invariance Techniques TLS-ESPRIT)的欠密度流星余迹干扰抑制算法.首先应用复数据经验模式分解估算流星余迹干扰的位置,并将该位置的回波数据组成Hankel矩阵,然后采用TLS-ESPRIT方法求解Hankel矩阵,解得流星余迹干扰的时域回波,最后从回波数据中去除流星余迹干扰的时域回波,得到流星余迹干扰抑制后的回波数据.与现有流星余迹抑制算法相比,该方法减少了流星余迹干扰的残余和提高了目标的信杂比(SCNR). 相似文献
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Lach S.R. Amin M.G. Lindsey A.R. 《Selected Areas in Communications, IEEE Journal on》1999,17(4):704-714
A new method is introduced for interference excision in spread-spectrum communications that is conducive to software-radio applications. Spare processing capacity in the receiver permits the use of time-frequency techniques to synthesize a nonstationary interference from the time-frequency domain using least squares methods. The synthesized signal is then subtracted from the incoming data in the time domain, leading to jammer removal and increased signal-to-interference-and-noise ratio at the input of the correlator. The paper focuses on jammers with constant modulus that are uniquely described by their instantaneous frequency characteristics. With this a priori knowledge, the jammer signal amplitude is restored by projecting each sample of the synthesized signal to a circle representing its constant modulus. With the phase matching provided by the least squares synthesis method and amplitude matching underlying the projection operation, a significant improvement in receiver performance/bit-error rates is achieved over the case where no projection is performed. Software-radio aspects including computational complexity and processing modes are also discussed 相似文献
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Joint time-frequency ISAR using adaptive processing 总被引:6,自引:0,他引:6
A new joint time-frequency inverse synthetic aperture radar (ISAR) algorithm that combines ISAR processing with the joint time-frequency signal representation is presented as a means of extracting the nonpoint-scattering features from the standard ISAR image. The adaptive Gaussian representation, applied to the range aids of the ISAR image, is used as the time-frequency processing engine. This technique uses Gaussian basis functions to adaptively parameterize the data and, as a consequence, the point-scattering mechanisms and resonance phenomena can be readily separated based on the width of the Gaussian bases. The adaptive joint time-frequency ISAR algorithm is tested using data generated by the moment-method simulation of simple structures and the chamber measurement data from a scaled model airplane. The results show that nonpointscattering mechanisms can be completely removed from the original ISAR image, leading to a cleaned image containing only physically meaningful scattering centers. The nonpoint-scattering mechanisms, when displayed in the frequency-aspect plane, can be used to identify target resonances and cutoff phenomena 相似文献
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A time-frequency analysis method to study electromagnetic scattering is presented and demonstrated using canonical objects. The time-frequency analysis method utilizes the Bargmann transform to formulate the signal representation in phase space. The use of the Bargmann transform leads to an attractive parametric signal representation in terms of complex polynomials, and elliptical filters can be constructed to crop or extract selected areas of the phase plane. The signal representation and filtering operations are demonstrated using scattering responses from spheres and thin wires, and the prominent scattering features are identified and extracted 相似文献
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Pieraccini M. Luzi G. Noferini L. Mecatti D. Atzeni C. 《Geoscience and Remote Sensing, IEEE Transactions on》2004,42(2):309-317
Joint time-frequency analysis of penetrating radar response has been tested using simulated and experimental data as a processing tool for detecting stratified features inside a masonry structure. The radar response has been simulated exploiting the formalism of the propagators inside a finite number of dielectric layers. Experimental testing has been carried out by varying the thickness of the hollow space between two walls. 相似文献
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A generalized approach for interference suppression in PN spread spectrum communications using open-loop adaptive excision filtering is introduced. The excision filter coefficients under this technique depend on the jammer power and its instantaneous frequency (IF) information, and both values can be gained in the time-frequency domain. The dependency of the excision filter characteristics on the interference power, which was absent in past contributions in this area, is of significant importance as it allows optimum tradeoff between interference removal and the amount of self-noise generated from the induced correlation across the PN chip sequence, due to filtering. This tradeoff is bounded by the two extreme cases of no self-noise, which implies preprocessing disabled, and full interference excision, which the case previously considered. In this paper, we derive the FIR excision filters that maximize the receiver signal-to-noise ratio for narrowband interference and discuss the generalization to nonstationary jamming environment 相似文献
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Chong-Ni Li Guang-Rui Hu Min-Jie Liu 《Selected Areas in Communications, IEEE Journal on》2000,18(3):403-406
Among many transform-domain interference excision techniques, transform-domain adaptive filtering has many advantages. It is based on a true optimization of some particular performance parameters such as the bit-error rate (BER). Moreover, it is insensitive to jammer frequency. However, transform-domain adaptive filtering also has the drawback of being incapable of tracking a rapidly changing interference because most adaptive algorithms require time to converge to the optimal solution. In this paper, a self-orthogonalizing transform-domain least mean square (SO-TRLMS) algorithm is used to speed up the convergence. Compared to a traditional transform-domain least mean square (TRLMS) algorithm, the SO-TRLMS algorithm can significantly improve the convergence rate of the LMS algorithm, thus making the transform-domain adaptive filtering technique more suitable for real-time processing. In order to show how the system performance is affected by various factors such as interference power and the transform used, this paper presents an analytical result for the BER performance that is applicable for arbitrary orthogonal linear transforms. Simulation results are also presented to demonstrate the validity of the analysis 相似文献
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《Signal Processing Magazine, IEEE》1999,16(2):81-93
The Fourier transform has been widely used in radar signal and image processing. When the radar signals exhibit time- or frequency-varying behavior, an analysis that can represent the intensity or energy distribution of signals in the joint time-frequency (JTF) domain is most desirable. In this article, we showed that JTF analysis is a useful tool for improving radar signal and image processing for time- and frequency-varying cases. We applied JTF analysis to radar backscattering and feature extraction; we also examined its application to radar imaging of moving targets. Most methods of JTF analysis are non-parametric. However, parametric or model-based methods of time-frequency analysis, such as adaptive Gaussian and chirplets, are more suitable for radar signals and images 相似文献
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针对按频率均匀划分子信道的数字信道化技术缺乏灵活性、资源利用率低等问题,提出了一种基于信号时间-频率特征分析的自适应信道化技术.对中频数据进行时-频分析,根据信号时-频特征参数差异对子信道进行跟踪、聚类,自适应动态调整参与反变换的子信道,实现宽带复杂调制信号的完整截获、跟踪、分离.仿真分析结果验证了算法的有效性,且其计... 相似文献
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Nabeel Ali Khan Sadiq Ali Magnus Jansson 《Multidimensional Systems and Signal Processing》2018,29(2):503-521
Time-frequency distributions (TFDs) allow direction of arrival (DOA) estimation algorithms to be used in scenarios when the total number of sources are more than the number of sensors. The performance of such time–frequency (t–f) based DOA estimation algorithms depends on the resolution of the underlying TFD as a higher resolution TFD leads to better separation of sources in the t–f domain. This paper presents a novel DOA estimation algorithm that uses the adaptive directional t–f distribution (ADTFD) for the analysis of close signal components. The ADTFD optimizes the direction of kernel at each point in the t–f domain to obtain a clear t–f representation, which is then exploited for DOA estimation. Moreover, the proposed methodology can also be applied for DOA estimation of sparse signals. Experimental results indicate that the proposed DOA algorithm based on the ADTFD outperforms other fixed and adaptive kernel based DOA algorithms. 相似文献
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Transient analysis of data-normalized adaptive filters 总被引:1,自引:0,他引:1
This paper develops an approach to the transient analysis of adaptive filters with data normalization. Among other results, the derivation characterizes the transient behavior of such filters in terms of a linear time-invariant state-space model. The stability, of the model then translates into the mean-square stability of the adaptive filters. Likewise, the steady-state operation of the model provides information about the mean-square deviation and mean-square error performance of the filters. In addition to deriving earlier results in a unified manner, the approach leads to stability and performance results without restricting the regression data to being Gaussian or white. The framework is based on energy-conservation arguments and does not require an explicit recursion for the covariance matrix of the weight-error vector. 相似文献