本文選題：鎖相環(huán) + 超短波接收機　； 參考：《大連海事大學》2014年碩士論文

【摘要】：近年來,隨著社會需求的日益增長,無線通信技術(shù)已發(fā)展成為信息行業(yè)中最為耀眼的明星,而超短波技術(shù)作為其重要分支,不再僅限于專業(yè)范疇的應用,而是廣泛延伸到各個領(lǐng)域中,如軍事、交通、醫(yī)療及漁業(yè)等。 本文的主要研究內(nèi)容是基于27.5MHz～39.5MHz頻段調(diào)頻接收機的前端電路的研究與設計。在綜合比較多種方案后,最終選擇了超外差兩次混頻結(jié)構(gòu),該結(jié)構(gòu)主要包括前置濾波器、自動增益控制(AGC)放大器、混頻器、鎖相環(huán)(PLL)頻率合成器和調(diào)頻解調(diào)電路等幾個部分,其特點是易于實現(xiàn)系統(tǒng)的高靈敏度和大動態(tài)范圍。其中,鎖相環(huán)頻率合成器電路主要是用于產(chǎn)生接收機中的本振信號。根據(jù)設計方案,本文著重對各結(jié)構(gòu)模塊進行了深入研究,并設計構(gòu)建了符合設計要求的超短波接收機的硬件平臺系統(tǒng)。此系統(tǒng)首先對天線接收到的射頻信號進行濾波、放大和兩次混頻處理,再通過正交鑒頻器進行解調(diào),最后輸出音頻信號。 本文首先就課題的背景和接收機的現(xiàn)狀進行了闡述；其次對接收機的相關(guān)性能指標進行了詳細分析,其中包括有靈敏度、線性度、噪聲系數(shù)等；隨后具體討論了硬件電路的設計,主要有鎖相環(huán)頻率合成器、前置濾波器、自動增益控制電路、混頻器、窄帶調(diào)頻電路等模塊,并同時給出各模塊的原理圖以及部分電路的仿真圖；最后就系統(tǒng)硬件進行了測試,并對測試中遇到的問題及測試結(jié)果進行了分析。測試結(jié)果顯示：所設計的系統(tǒng),其指標基本符合設計要求。
[Abstract]:In recent years, with the increasing demand of society, wireless communication technology has developed into the most dazzling star in the information industry, and ultrashort wave technology, as an important branch of it, is no longer limited to professional applications. It extends to a wide range of areas, such as military, transportation, medical and fishing. The main research content of this paper is the research and design of front-end circuit based on 27.5MHz~39.5MHz frequency modulation receiver. After a comprehensive comparison of various schemes, the superheterodyne twice mixing structure is finally selected. The structure mainly includes prefilter, automatic gain control (AGC) amplifier, mixer, PLL frequency synthesizer and frequency modulation demodulation circuit, etc. Its characteristic is that it is easy to realize the high sensitivity and large dynamic range of the system. The PLL frequency synthesizer is mainly used to generate the local oscillator signal in the receiver. According to the design scheme, this paper focuses on the in-depth study of each structural module, and designs and constructs the hardware platform system of ultrashort wave receiver which meets the design requirements. In this system, the RF signals received by the antenna are first filtered, amplified and mixed twice, then demodulated by a quadrature frequency discriminator, and finally the audio signal is output. In this paper, the background of the subject and the current situation of the receiver are described, and then the performance of the receiver is analyzed in detail, including sensitivity, linearity, noise coefficient and so on. Then, the design of hardware circuit is discussed in detail, including phase-locked loop frequency synthesizer, prefilter, automatic gain control circuit, mixer, narrowband frequency modulation circuit and so on. At the same time, the schematic diagram of each module and the simulation diagram of some circuits are given. Finally, the hardware of the system is tested, and the problems encountered in the test and the test results are analyzed. The test results show that: the system designed, its index is basically in line with the design requirements.
【學位授予單位】：大連海事大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TN858

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