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对流层散射通信信道建模及系统性能仿真 总被引:2,自引:1,他引:1
对流层散射通信是一种利用对流层媒质的不均匀性来实现超视距通信的方式.在分析对流层散射信道的统计特性的基础上,根据WSSUS假设建立了快衰落特性下的散射信道仿真模型,并进行了系统性能的实验仿真.同时通过理论计算,得出了该信道误码率的理论曲线,并与仿真结果进行比较,证明了对流层散射信道模型的合理性,该模型为分析系统的性能提供了一个有效的系统平台. 相似文献
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多径效应造成的符号间干扰是大容量散射传输所遇到的首要问题.根据文献中提出的基于二阶循环统计量的直接盲均衡算法,依据最小均方误差准则,对接收到的信号进行过采样,构造了一个线性的分数间隔均衡器,并用它来均衡对流层散射信道,获得了较好的均衡效果.由于该算法不经过信道盲辨识而直接均衡信道,因此受信道阶教误差的影响较小,且该算法与传统的基于二阶矩的两步均衡算法相比,具有计算简单,精度高的特点. 相似文献
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The energy-dispersive spectroscopy (EDS), X-ray diffraction analysis (XRD) and differential thermal analysis (DTA) were used to analyze the melting, spreading process, and reaction mechanism of non-corrosive flux on the surface of aluminum. The result indicates that the whole process can be divided into three stages. In the first stage, flux is heated from room temperature to its melting point, which is called the endothermic stage, mainly absorbs heat and generates a small amount of liquid flux. When the temperature exceeds the melting point of flux, a large amount of liquid flux is generated and reacts with oxide films on the surface of aluminum. This stage is called the reaction stage. The third stage is a spreading and cleaning process, in which residues and reaction products quickly flow out from the center with liquid flux. The different compositions of flux perform different functions in brazing. K3AlF6 can remove oxide film as a cleaner. Only in liquid or molten state can flux remove oxide film on the substrate. 相似文献
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