共查询到19条相似文献,搜索用时 125 毫秒
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传统跳时脉冲位置调制(THPPM)系统未考虑系统在全频段的利用率,为此,提出了一种提高系统频谱利用率的方法.基于FCC室内辐射掩蔽,通过组合1~13阶高斯脉冲,设计了一种逼近规范的组合脉冲,建立了使用该组合脉冲的THPPM通信系统仿真模型,给出了接收信号与掩膜的仿真波形和模型内部结构图.与使用传统脉冲滤波器的系统频谱利用率进行了分析和比较,仿真结果表明,通过应用组合脉冲显著提高了系统在全频段的利用率.此外,对Simulink设计的模块进行封装,独立组建了超宽带模块库,简化了仿真过程,扩展了Simulink在超宽带方面的应用. 相似文献
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频谱共存与兼容问题是超宽带无线通信领域必须解决的一个关键问题.为了避免超宽带系统对现有窄带无线系统的干扰,一个有效的设计方法是设计适合传输的脉冲波形.将超宽带脉冲波形设计问题等效为切比雪夫函数逼近问题,利用数值分析中Remez算法,通过一次次迭代可以获得满足要求的超宽带脉冲.Matlab仿真结果表明,用这种方法设计的脉冲功率谱符合目标频谱掩模的约束要求,在二进制脉冲位置调制跳时超宽带系统中,这种脉冲在高斯信道下单链路误比特率和多用户等方面的性能要优于高斯二阶导数脉冲. 相似文献
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从频域角度探讨TH-UWB系统对窄带干扰的抑制能力,采用信号功率谱分析方法,研究UWB系统的调制技术和脉冲成形技术,提出线性组合高斯单周脉冲设计陷波频谱.理论分析及计算机仿真结果表明,合理选择超宽带信号调制方式和脉冲,可在一定程度上提高超宽带系统抗干扰能力.应用提出的线性组合高期单周脉冲作为UWB发射信号,可以有效减小UWB信号对外界的干扰. 相似文献
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提出一种基于Parks-McClellan算法设计超宽带脉冲的方法,将脉冲设计等效为切比雪夫函数逼近问题。设计方法简单灵活,可满足各种幅频特性要求。Matlab仿真结果表明所设计脉冲的功率谱充分满足FCC频谱掩模要求并且频带利用率较高。 相似文献
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针对超宽带传输参考接收机模板信号包含噪声的问题,引入了一种新型的超宽带传输参考接收机结构,重点分析了该接收机的原理及性能。通过仿真验证,该新型的超宽带传输参考接收机性能相比平均超宽带传输参考接收机有很大提升。 相似文献
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研究工作中用EDA工具对周期性信号作频谱分析问题时,由此得到的频谱分析与周期性信号频谱的理论分析存在着一定的偏差.理论的信号幅度谱具有谐波性,是离散的谱线,而仿真环境下的谱线在频率点有畸变.通过信号谱分析的理论,结合EDA仿真工具分析的特点,将两种频谱分析的偏差来源归结于周期信号的时域加窗效应.分析r频谱产生偏差的原因,并对理论分析谱和仿真分析谱的特点给予归纳.最后的仿真分析也证实了给出的分析结果. 相似文献
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从无线电频谱管理及频谱有效利用的角度描述了世界主要发达国家对超宽带无线电 UWB 无线技术的应用现状,提出了我国制定 UWB 技术频谱模板的基本出发点与考虑因素,以促进超宽带无线电 UWB 在我国的发展与应用。 相似文献
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提出了一种新的超宽带脉冲的设计方法。采用不同幅度和延迟的高斯脉冲的组合来拟合抽样函数脉冲,实现了超宽带辐射掩蔽的高效逼近。该方法产生的脉冲波形具有实现简单、持续时间短、容易进行时域或频域调节等特点。在介绍设计原理的基础上,给出了设计时域波形的具体实现及波形所对应的功率谱密度图,使其满足辐射掩蔽的要求。最后,分析了TH-PPM UWB系统的传输性能,并和最佳单周期高斯波形进行了详细的比较,结果表明其误码性能远远优于最佳单周期高斯波形。 相似文献
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首先对修正Hermite函数n阶导数的能量归一化与脉冲形状参数α、n的关系进行了研究,根据美国联邦通信委员会(FCC)对超宽带(UWB)脉冲的有关辐射掩蔽的标准提出了设计UWB脉冲的新方法,通过N个修正Hermite函数的线性组合来得到最优波形。仿真结果表明优化脉冲能够接近于辐射掩蔽,使得传输功率在低于FCC限定的条件下取得更大值。 相似文献
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In the ultra-wideband (UWB) communication systems, a critical spectral mask is released to restrict the allowable interference to other wireless devices by the Federal Communications Commission (FCC), and then some pulse shaping methods have been presented to fulfil the mask. However, most pulse shaping methods do not consider the antenna distortion which cannot be neglected in the UWB communication systems compared with the conventional systems. To this end, an orthogonal wavelet based pulse shaping method is proposed in this paper to integrate compensation of antenna distortion into pulse shaping. Simulation results show that the novel pulse shaping method can be used to achieve compensation for antenna distortion, optimization of transmission power spectrum, and simplification of the algorithm, as well as simple implementation of the pulse generator. 相似文献
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The design of echo state network (ESN) parameters relies on the selection of the maximum eigenvalue of the linearized system around zero (spectral radius). However, this procedure does not quantify in a systematic manner the performance of the ESN in terms of approximation error. This article presents a functional space approximation framework to better understand the operation of ESNs and proposes an information-theoretic metric, the average entropy of echo states, to assess the richness of the ESN dynamics. Furthermore, it provides an interpretation of the ESN dynamics rooted in system theory as families of coupled linearized systems whose poles move according to the input signal dynamics. With this interpretation, a design methodology for functional approximation is put forward where ESNs are designed with uniform pole distributions covering the frequency spectrum to abide by the richness metric, irrespective of the spectral radius. A single bias parameter at the ESN input, adapted with the modeling error, configures the ESN spectral radius to the input-output joint space. Function approximation examples compare the proposed design methodology versus the conventional design. 相似文献
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Filtering is one of the important techniques in computer vision. It has been widely used in edge detection, image restoration, range image segmentation, etc. However, the efficient implementation of an arbitrary filter has been a challenging problem until now. In this paper, a novel method is proposed to implement an arbitrary filter. Firstly, an efficient recursive structure is proposed to implement any (polynomial) × (exponential)-type (PET) filter. The computational complexity and structure are independent of its filter mask size or its bandwidth. Secondly, a new method is proposed—Lagurre spectrum decomposition method—to obtain the PET approximation of any filters. As an example, the above method is applied to the approximation and implementation of Gaussian filters and experiments have shown that a perfect approximation can be obtained with only third-order Lagurre bases, and therefore only a fourth-order recursive filter is needed to implement Gaussian filters. Finally, the comparison of the present method with the known ones shows that (1) Lagurre polynomial bases are orthogonal with each other, so the filter approximation is simple, (2) the bases are complete and the completeness guarantees the approximation error can be reduced to zero, (3) the method can be used to design both Gaussian and any other filters. 相似文献
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Humberto Contreras 《Computers & Structures》1978,9(6):615-620
A second moment point approximation for any well behaved function of a random vector was programmed in a pocket calculator and with it the stiffness matrix of a beam element and the optimum spectral acceleration for a structure design are computed taking into account parameter uncertainty. The usefullness of pocket programable calculators in engineering design is demonstrated. 相似文献
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Single-Channel Speech Separation Using Soft Mask Filtering 总被引:2,自引:0,他引:2
Radfar M.H. Dansereau R.M. 《IEEE transactions on audio, speech, and language processing》2007,15(8):2299-2310
We present an approach for separating two speech signals when only one single recording of their linear mixture is available. For this purpose, we derive a filter, which we call the soft mask filter, using minimum mean square error (MMSE) estimation of the log spectral vectors of sources given the mixture's log spectral vectors. The soft mask filter's parameters are estimated using the mean and variance of the underlying sources which are modeled using the Gaussian composite source modeling (CSM) approach. It is also shown that the binary mask filter which has been empirically and extensively used in single-channel speech separation techniques is, in fact, a simplified form of the soft mask filter. The soft mask filtering technique is compared with the binary mask and Wiener filtering approaches when the input consists of male+male, female+female, and male+female mixtures. The experimental results in terms of signal-to-noise ratio (SNR) and segmental SNR show that soft mask filtering outperforms binary mask and Wiener filtering. 相似文献