超短波接收机射频前端电路的研究与设计

发布时间：2018-05-14 21:22

本文选题：锁相环 + 超短波接收机　；参考：《大连海事大学》2014年硕士论文

【摘要】：近年来,随着社会需求的日益增长,无线通信技术已发展成为信息行业中最为耀眼的明星,而超短波技术作为其重要分支,不再仅限于专业范畴的应用,而是广泛延伸到各个领域中,如军事、交通、医疗及渔业等。本文的主要研究内容是基于27.5MHz～39.5MHz频段调频接收机的前端电路的研究与设计。在综合比较多种方案后,最终选择了超外差两次混频结构,该结构主要包括前置滤波器、自动增益控制(AGC)放大器、混频器、锁相环(PLL)频率合成器和调频解调电路等几个部分,其特点是易于实现系统的高灵敏度和大动态范围。其中,锁相环频率合成器电路主要是用于产生接收机中的本振信号。根据设计方案,本文着重对各结构模块进行了深入研究,并设计构建了符合设计要求的超短波接收机的硬件平台系统。此系统首先对天线接收到的射频信号进行滤波、放大和两次混频处理,再通过正交鉴频器进行解调,最后输出音频信号。本文首先就课题的背景和接收机的现状进行了阐述；其次对接收机的相关性能指标进行了详细分析,其中包括有灵敏度、线性度、噪声系数等；随后具体讨论了硬件电路的设计,主要有锁相环频率合成器、前置滤波器、自动增益控制电路、混频器、窄带调频电路等模块,并同时给出各模块的原理图以及部分电路的仿真图；最后就系统硬件进行了测试,并对测试中遇到的问题及测试结果进行了分析。测试结果显示：所设计的系统,其指标基本符合设计要求。
[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.
【学位授予单位】：大连海事大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN858

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