相干声源激励不均匀体及其在散射通信的应用

发布时间：2018-04-01 03:15

本文选题：相干声源　切入点：对流层人工变态　出处：《西安电子科技大学》2015年硕士论文

【摘要】：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一种通信方式。与其他通信方式相比,对流层散射通信具有单跳跨距远、通信容量大、抗干扰能力强、抗截获能力强、抗摧毁能力强、抗核爆能力强,以及能跨越复杂地形进行全天候可靠通信等突出优点。同时,由于其独特的通信机理也导致了两大致命弱点:散射损耗大、信道特性完全依赖自然湍流结构而导致强烈的随机性。所以,寻找一种有效途径从而克服对流层散射通信的弱点进而充分利用其优点具有重要的理论意义和应用价值。本文提出了通过利用相干声源激励大气折射指数不均匀体的技术途径,并且将这种大气折射指数人工不均匀体应用于对流层散射通信中。本文主要的研究内容如下:对声波传播的特性以及声波的叠加原理进行简单地介绍,对声波的干涉现象进行了描述。同时,在大气声吸收基本知识的基础上,分析了大气的吸声系数随各个参数的变化关系,计算了声波的衰减因子随高度的变化关系。讨论了几类基本声源的特征,并对其声辐射的指向特性及声场进行了分析与讨论。在此基础上由分波振面法建立了相干声源模型,分别包括线阵列声源模型以及点阵列声源模型两种模型,分析研究了这两类阵列声源所产生的声压分布特征,仿真了阵列因子,并且讨论了点阵列声源所产生的大气折射指数起伏有效值的分布同阵列声源的变化关系。推导了大气折射指数的有效值以及其瞬时值同声压的关系,讨论了介电常数起伏与大气折射指数起伏的关系,讨论了这两类阵列结构的声源所产生的声压分布极大值的存在条件,计算了大气折射指数起伏同高度以及其他参数的变化关系。对对流层散射通信的基础知识进行了介绍,描述了这种通信方式的缺点以及对其进行性能改善的途径。首次建立了相干声源激励大气折射指数不均匀体及其定向影响对流层散射通信的实验模型,通过设计这种以分波振面法为基础的相干声源,并且设置适当的参数,实验验证了声波扰动对流层散射通信的可行性。本论文为声波扰动对流层散射通信的发展奠定了一定的理论基础以及实验依据。
[Abstract]:Tropospheric scattering communication is a communication method which utilizes the inhomogeneity of tropospheric media to realize over-the-horizon communication.Compared with other communication methods, troposcatter communication has a long span, large communication capacity, strong anti-jamming ability, strong anti-interception ability, strong anti-destruction ability, strong anti-nuclear explosion ability.And the ability to cross the complex terrain for all-weather reliable communications and other outstanding advantages.At the same time, due to its unique communication mechanism, it also leads to two major fatal weaknesses: high scattering loss, channel characteristics completely dependent on natural turbulence structure, resulting in strong randomness.Therefore, it is of great theoretical significance and practical value to find an effective way to overcome the weakness of tropospheric scattering communication and make full use of its advantages.In this paper, a technique is proposed to excite the inhomogeneous body of atmospheric refraction index by means of coherent sound source, and the artificial inhomogeneity of atmospheric refraction index is applied to tropospheric scattering communication.The main contents of this paper are as follows: the characteristics of sound wave propagation and the superposition principle of sound wave are briefly introduced, and the interference phenomenon of sound wave is described.At the same time, based on the basic knowledge of atmospheric acoustic absorption, the variation of atmospheric sound absorption coefficient with each parameter is analyzed, and the variation of attenuation factor of sound wave with height is calculated.The characteristics of several kinds of basic sound sources are discussed, and the directional characteristics and sound field of their sound radiation are analyzed and discussed.On the basis of this, the coherent sound source model is established by the method of the divider vibration surface, including the linear array sound source model and the point array sound source model respectively. The characteristics of sound pressure distribution produced by these two kinds of array sound sources are analyzed and the array factors are simulated.The relationship between the distribution of the effective value of atmospheric refraction index fluctuation and the variation of the array sound source is discussed.The relationship between the effective value of atmospheric refraction index and its instantaneous sound pressure is derived, and the relationship between dielectric constant fluctuation and atmospheric refraction index fluctuation is discussed.The existence conditions of the maximum of sound pressure distribution produced by the sound sources of these two kinds of array structures are discussed, and the relationship between the fluctuation of atmospheric refraction index and the height and other parameters is calculated.The basic knowledge of tropospheric scattering communication is introduced. The shortcomings of this communication mode and the ways to improve its performance are described.For the first time, an experimental model of atmospheric refraction index inhomogeneity excited by coherent sound source and its directional effect on tropospheric scattering communication is established. By designing the coherent sound source based on the divide-wave vibration surface method and setting appropriate parameters,The feasibility of acoustic disturbance tropospheric scattering communication is verified by experiments.This paper provides a theoretical basis and experimental basis for the development of acoustic disturbance tropospheric scattering communication.
【学位授予单位】：西安电子科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN926

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