本文選題：自由空間光通信 + 可編程邏輯器件��； 參考：《重慶大學(xué)》2016年碩士論文

【摘要】：光通信可分為有線光通信和無線光通信,兩者存在各自的優(yōu)缺點(diǎn)。自由空間光通信是無線光通信的一個(gè)分支,它兼?zhèn)淞擞芯�光通信和無線光通信的優(yōu)勢,不但具有傳輸速率高、頻帶寬、保密性好等優(yōu)點(diǎn),而且還不需要預(yù)先鋪設(shè)通信鏈路、安裝靈活方便,因而受到了廣泛的關(guān)注和研究。本文基于自由空間光通信和語音編解碼算法理論,利用可編程邏輯器件、激光器、聲光調(diào)制器和光電倍增管等設(shè)備搭建了無線光語音通信系統(tǒng)平臺(tái)。本文對自由空間光通信的相關(guān)理論、語音信號數(shù)字化過程以及語音編解碼算法的分類進(jìn)行分析介紹,確定選擇波形編解碼中的A率和ADPCM編解碼算法作為本通信系統(tǒng)的研究目標(biāo)。在編解碼算法確定后,對通信系統(tǒng)的整體框架進(jìn)行擬定,并對系統(tǒng)中關(guān)鍵器件的工作原理進(jìn)行介紹,做出對比分析和選擇。最終選擇波長為637nm的半導(dǎo)體激光器為激光光源,PMT為光電探測器,聲光調(diào)制器為外調(diào)制器來實(shí)現(xiàn)語音通信系統(tǒng)的搭建。為了保證通信系統(tǒng)工作的正常進(jìn)行,對語音通信系統(tǒng)的發(fā)射端和接收端的相關(guān)編解碼程序模塊進(jìn)行編譯和仿真,分析各個(gè)子模塊的功能是否正常實(shí)現(xiàn)。同時(shí)對系統(tǒng)的關(guān)鍵器件如激光光源、聲光調(diào)制器等進(jìn)行測試。測試結(jié)果表明激光器可以接受低于5MHz的外調(diào)制和低于30MHz的內(nèi)調(diào)制。同時(shí)對聲光調(diào)制器在輸入不同類型、幅值以及頻率的調(diào)制信號時(shí)進(jìn)行測試,結(jié)果表明需要對調(diào)制器輸入幅值大于2.4V的TTL方波信號來實(shí)現(xiàn)數(shù)字調(diào)制。基于以上的設(shè)計(jì)與選擇,本文首先使用波形編解碼算法中較為簡單的A率編解碼算法進(jìn)行系統(tǒng)的搭建與測試,并在A率編解碼算法實(shí)現(xiàn)的基礎(chǔ)上進(jìn)行了ADPCM編解碼算法的設(shè)計(jì)與驗(yàn)證,并成功搭建通信系統(tǒng)平臺(tái),在室內(nèi)進(jìn)行了多次實(shí)驗(yàn),由人工接收解碼后的信號來進(jìn)行判定,經(jīng)過多次測試,得到MOS值在4.0左右,能夠?qū)⑿畔⒉皇д娴貍鬟_(dá),基本上實(shí)現(xiàn)了正常的語音通信。最后,對全文做出總結(jié),針對本文的實(shí)驗(yàn)結(jié)果和未來可做的改進(jìn)工作做進(jìn)一步分析。
[Abstract]:Optical communication can be divided into wired optical communication and optical wireless communication, both have their own advantages and disadvantages. Free space optical communication is a branch of optical wireless communication, it is both wired and optical communications and optical wireless communication, not only has high transmission rate, wide bandwidth, good security, but also not prior to the laying of the communication link, flexible and convenient installation, which has received extensive attention and research. In this paper, free space optical communication and speech codec algorithm based on the theory of the use of programmable logic devices, laser, acousto-optic modulator and photomultipliers, and other equipment to build optical wireless voice communication system platform. This paper on free space theory optical communication, digital speech signal classification and speech codec algorithm are introduced to determine the choice of waveform codec rate in A and ADPCM decoding algorithm for the communication system. Study on the target system. The codec algorithm is determined, the overall framework of the communication system was proposed, and the working principle of the key components of the system are introduced, and make a comparative analysis. Finally 637nm diode laser as the laser source, PMT photodetector, acousto-optic modulator for external modulator to achieve build a voice communication system. In order to ensure the normal operation of the communication system, the related series of voice communication system for transmitting and receiving end of the decoding program module was compiled and simulated, the analysis of each module function is normal. At the same time the system of key devices such as laser source, acousto-optic modulator is tested. The test results show that the laser can accept less than 5MHz and lower than the internal external modulation 30MHz modulation. At the same time for different types of input in the acousto-optic modulator, amplitude and frequency To test the modulation signal, the results indicate the need for more than 2.4V of TTL amplitude modulator input square wave signal to realize digital modulation. Design and selection based on the above, this paper use waveform codec algorithm in a relatively simple A rate codec algorithm to build and test system, and the design and verification of ADPCM codec algorithm on the basis of A rate codec algorithm realization, and successfully build communication platform, a number of experiments performed in the laboratory, by artificial signal receiving decoded to determine, after repeated testing, the value of MOS at around 4, will be able to convey information without distortion, basically realizes the normal speech communication at last, make a summary of this thesis, further analysis on the experiment results and improvement work to do in the future.

【學(xué)位授予單位】：重慶大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2016
【分類號】：TN929.1

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