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将von Mises分布作为多径散射接收信号的功率密度分布,在存在稳定直射分量的条件下,推导出相应的多天线Rice信道中的多径角度扩展公式,进而推导出了小尺度Rice衰落信道中紧凑阵元空间相关系数的近似表达式。von Mises分布的集中度参量对多径角度扩展的影响较Rice因子更为明显。只要多径散射是各向同性的,阵元间的空间相关性较弱;只要多径散射是各向异性的,空间相关性将随直射分量功率增大而急剧增加。分析表明,角度扩展和阵元间距是影响接收信号空间衰落相关性的主要因素。 相似文献
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天线组阵技术是提高深空探测微弱信号信噪比的有效方法。随着大规模天线组阵中单个天线接收信号信噪比的降低,来自背景天体的相关噪声的影响不容忽视。针对相关噪声对天线组阵SUMPLE算法权值估计的影响进行了分析,给出了一种基于频域的抑制相关噪声影响的处理方法。计算机仿真结果表明:在相关噪声背景下,该方法能有效地提高SUMPLE算法权值相位的估计精度,抑制相关噪声的干扰。 相似文献
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涡旋波束的中空发散特性,导致其远距离传输下接收困难。且传输信道中的多径效应会造成涡旋波束的相位畸变和模态间干扰问题,影响涡旋电磁波信号的传输质量。针对上述问题,建立了基于部分孔径取样接收方案的稀疏多径涡旋电磁波无线传输模型,分析了多径数目、天线阵列数目、传输距离、信噪比等参数对部分接收涡旋通信系统传输性能的影响。仿真结果表明:随着传输距离不断增大,基于部分孔径取样接收的涡旋系统与基于完整孔径取样接收的涡旋系统信道容量间的相对差异越来越小,由此证明了在稀疏多径环境中,部分孔径取样接收涡旋通信系统的可行性。 相似文献
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在动目标显示型雷达系统中,平台运动效应和天线扫描效应同时得到补偿。对天线扫描效应来讲,利用来自天线辅助子阵的信号来补偿由天线主子阵来的信号。然后,来自主子阵的经延时和扫描补偿的信号与来自主子阵的未经延时和补偿的信号合成,以形成补偿扫描运动和平台运动效应的信号。第一种装置在每个对消级上提供一个具有运动补偿的杂波对消器。第二种装置为作进一步动目标显示处理提供多个(N个)在时间和相位上同步的运动补偿信号。 相似文献
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提出一种偶极子天线单元构成的极化敏感阵列用于全球卫星导航信号的接收,经过阵列信号波束形成后,在抗干扰的同时保留卫星导航信号中载波相位测量值的准确性,可用于基于载波相位测量的高精度差分定位。与传统的圆极化天线阵列相比,该阵列具有阵元构造简单、尺寸小的特点。通过建立极化阵列接收信号模型,分析了天线极化和波束形成算法对卫星导航信号相位的影响,给出了相适应的相位中心稳定的数字波束形成算法。仿真验证了分析的正确性和算法的有效性。 相似文献
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Locating GSM mobiles using antenna array 总被引:1,自引:0,他引:1
The authors consider the problem of accurate estimation of the position of a GSM mobile station based on measurements of the mobile signal made at a single receiving site equipped with an antenna array. Direction of arrival and time of arrival measurements are used to estimate the location of the mobile transmitter. A statistical filtering technique is applied to the location estimates to minimise the effects of multipath fading. Experimental results with a DCS-1800 system are presented which achieve an r.m.s. location error of 133 m, with the error being <250 m for 98% of the time 相似文献
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Chien-Hung Chen Chien-Ching Chiu Chun-Liang Liu 《Wireless Personal Communications》2007,42(4):575-586
The genetic algorithm is used to synthesize the radiation pattern of the directional circular arc array to minimize the bit
error rate (BER) performance in indoor wireless communication system. The impulse responses of the indoor channel for any
transmitter-receiver location are computed by shooting and bouncing ray/image techniques. By using the impulse response of
multipath channel, the performance of the synthesized antenna pattern on BPSK (binary phase shift keying) system with phase
and timing recovery circuits can be calculated. Based on the topography of the antenna and the BER formula, the synthesis
problem can be reformulated into an optimization problem and solved by the genetic algorithm. The novelty of our approach
is choosing BER as the object function instead of sidelobe level of the antenna pattern, i.e., BER performance is defined
as a object function to optimize the excitation coefficient of array by the genetic algorithm. The strong point of the genetic
algorithm is that it can find out the solution even if the performance index cannot be formulated by simple equations. Besides,
the genetic algorithm will converge to global extreme instead of local extreme and achieves a good antenna pattern. Numerical
results show that the synthesized antenna pattern is effective to combat the multipath fading and can increase the transmission
rate of indoor millimeter wave system. 相似文献
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研究了一种基于时域射线追踪技术(Time Domain Ray Tracing)适用于大尺度室内环境传播建模的IR-UWB信号传播模型。该模型综合考虑室内传播存在的多径效应、阴影效应和穿墙效应等物理现象,引入墙体内部的时域传输系数和墙体至空气的时域透射系数,分析并解释了时域传播系数的物理意义。模型利用了IR-UWB信号时域极窄的特点,与传统的FDTD方法相比,能够显著提高大尺度环境下的计算效率。最后通过与实测结果的对比,验证了该模型的有效性,详细研究了模型的计算精度及误差成因。 相似文献
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相控阵阵面在外场进行幅相测试时,地面折射波引起的多路径效应是一个主要的误差来源.文中介绍了一种在短时FFT基础上、从地面折射波叠加在直射波上的合成波信号中求解直射波信号的方法,并通过软件仿真采用了该方法校准幅相误差后、阵面波束性能的改善情况. 相似文献
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在阵列信号处理中,信号相关性的问题很容易引起混淆。一些文献简单地认为多径信号之间必定相干,从而在仿真实验中得出了不正确的结论。该文从信号相关性的基本概念出发,推导了单频点信号和带通信号下的互相关系数表达式,讨论了多径效应下信号之间的相关性,并指出了导致多径时延信号相关的各种参数,最后通过计算机仿真验证了文中的结论。 相似文献
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Our proposed millimeter-wave self-heterodyne transmission technique is a simple and cost-effective solution to frequency stability problems in millimeter-wave access systems. In addition, this technique enables integration of a high-sensitivity receiver with a combining antenna diversity system that is approximately as effective as a maximal-ratio-combining antenna diversity system for all directions of signal arrival. We explain how our newly developed 70-GHz-band transceiver using the millimeter-wave self-heterodyne transmission technique with a receiver-module array can greatly improve receiver sensitivity for all directions of signal arrival i.e., without affecting the signal reception beam pattern and how this can solve the signal-fading problem in a multipath signal propagation environment. We also theoretically demonstrate that receiver sensitivity improves in proportion to the number of elements in a receiver-module array, and experimentally confirm this using an experimental 70-GHz-band monolithic microwave integrated circuit transceiver with a 4/spl times/2 receiver-module array. We show that millimeter-wave signal propagation can be modeled using a two-path model, and that serious signal fading depends on the transceiver height and transmission distance. Carrier and modulated signal transmission experiments using our developed transceiver have revealed that use of a receiver-module array greatly reduces the signal-fading problem in a multipath signal propagation environment. In the signal transmission experiment, we succeeded in transmitting an orthogonal frequency-division multiplexing signal over a 4-m transmission distance with bit-error-free performance. 相似文献
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单通道阵列采用单个通道贯续接入各阵元进行采样,与常规阵列相比,单通道阵列减少了硬件成本以及通道幅相特性不一致问题对估计性能的影响,但现有研究均未考虑单通道阵列的阵元切换时间对系统性能的影响。为填补这一空白,首先参照常规阵列,明确了单通道阵列中窄带信号的带宽限制及其与单通道阵列阵元切换时间的关系;再以单通道阵列MUSIC算法为例,同时考虑信号带宽与单通道阵列阵元切换时间对单通道阵列协方差阵特性的影响,从理论上推导了单通道阵列MUSIC算法关于扩展相对带宽的一阶估计误差。最后对单通道阵列MUSIC算法与单通道阵列空间FFT算法在不同阵元切换时间下进行仿真,对两种算法测向误差与阵元切换时间的关系进行分析,验证了理论推导结果的正确性。 相似文献