發(fā)布時(shí)間：2018-04-01 03:15

  本文選題：相干聲源　切入點(diǎn)：對(duì)流層人工變態(tài)　出處：《西安電子科技大學(xué)》2015年碩士論文

【摘要】：對(duì)流層散射通信,是一種利用對(duì)流層媒質(zhì)的不均勻性來(lái)實(shí)現(xiàn)超視距通信的一種通信方式。與其他通信方式相比,對(duì)流層散射通信具有單跳跨距遠(yuǎn)、通信容量大、抗干擾能力強(qiáng)、抗截獲能力強(qiáng)、抗摧毀能力強(qiáng)、抗核爆能力強(qiáng),以及能跨越復(fù)雜地形進(jìn)行全天候可靠通信等突出優(yōu)點(diǎn)。同時(shí),由于其獨(dú)特的通信機(jī)理也導(dǎo)致了兩大致命弱點(diǎn):散射損耗大、信道特性完全依賴自然湍流結(jié)構(gòu)而導(dǎo)致強(qiáng)烈的隨機(jī)性。所以,尋找一種有效途徑從而克服對(duì)流層散射通信的弱點(diǎn)進(jìn)而充分利用其優(yōu)點(diǎn)具有重要的理論意義和應(yīng)用價(jià)值。本文提出了通過(guò)利用相干聲源激勵(lì)大氣折射指數(shù)不均勻體的技術(shù)途徑,并且將這種大氣折射指數(shù)人工不均勻體應(yīng)用于對(duì)流層散射通信中。本文主要的研究?jī)?nèi)容如下:對(duì)聲波傳播的特性以及聲波的疊加原理進(jìn)行簡(jiǎn)單地介紹,對(duì)聲波的干涉現(xiàn)象進(jìn)行了描述。同時(shí),在大氣聲吸收基本知識(shí)的基礎(chǔ)上,分析了大氣的吸聲系數(shù)隨各個(gè)參數(shù)的變化關(guān)系,計(jì)算了聲波的衰減因子隨高度的變化關(guān)系。討論了幾類基本聲源的特征,并對(duì)其聲輻射的指向特性及聲場(chǎng)進(jìn)行了分析與討論。在此基礎(chǔ)上由分波振面法建立了相干聲源模型,分別包括線陣列聲源模型以及點(diǎn)陣列聲源模型兩種模型,分析研究了這兩類陣列聲源所產(chǎn)生的聲壓分布特征,仿真了陣列因子,并且討論了點(diǎn)陣列聲源所產(chǎn)生的大氣折射指數(shù)起伏有效值的分布同陣列聲源的變化關(guān)系。推導(dǎo)了大氣折射指數(shù)的有效值以及其瞬時(shí)值同聲壓的關(guān)系,討論了介電常數(shù)起伏與大氣折射指數(shù)起伏的關(guān)系,討論了這兩類陣列結(jié)構(gòu)的聲源所產(chǎn)生的聲壓分布極大值的存在條件,計(jì)算了大氣折射指數(shù)起伏同高度以及其他參數(shù)的變化關(guān)系。對(duì)對(duì)流層散射通信的基礎(chǔ)知識(shí)進(jìn)行了介紹,描述了這種通信方式的缺點(diǎn)以及對(duì)其進(jìn)行性能改善的途徑。首次建立了相干聲源激勵(lì)大氣折射指數(shù)不均勻體及其定向影響對(duì)流層散射通信的實(shí)驗(yàn)?zāi)Ｐ?通過(guò)設(shè)計(jì)這種以分波振面法為基礎(chǔ)的相干聲源,并且設(shè)置適當(dāng)?shù)膮?shù),實(shí)驗(yàn)驗(yàn)證了聲波擾動(dòng)對(duì)流層散射通信的可行性。本論文為聲波擾動(dòng)對(duì)流層散射通信的發(fā)展奠定了一定的理論基礎(chǔ)以及實(shí)驗(yàn)依據(jù)。
[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.
【學(xué)位授予單位】：西安電子科技大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TN926

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