基于LED和APD光通信系统的设计与实现

发布时间：2018-03-17 01:35

本文选题：可见光通信系统　切入点：数字脉冲间隔调制　出处：《江南大学》2017年硕士论文　论文类型：学位论文

【摘要】：可见光通信技术的应用前景广阔,但是技术复杂、成本昂贵,目前尚未大规模应用,仍需要大量的研究。数据调制方式对可见光通信系统的实现有重要的影响,本文对目前可见光通信常用的数字脉冲间隔调制(DPIM)方式和正交频分复用(OFDM)调制方式进行研究。研究对比了在有保护时隙、无保护时隙、正极性调制、负极性调制多种情况下不同阶数的DPIM调制的码元结构、平均发射功率、带宽需求等之间的关系。研究了OFDM调制方式实现原理,给出了OFDM调制重要参数的选择依据。利用发光二极管(LED)和雪崩光电二极管(APD)实现可见光通信系统是目前实现可见光通信的主流方案。本文分析研究了LED的调制特性用于指导LED驱动电路的设计。在研究APD温度特性的基础上设计了实用的APD供电电路可以保证APD增益稳定。放大电路一般具有固定的带宽增益积,因此窄带通放大电路可以简化系统,提高信号增益,较小的带宽也可以更好的滤除低频电源噪声和高频杂波,提高信号信噪比。本文提出利用简易元器件构成窄带通放大电路制作了单向可见光通信系统。分析研究提出一阶DPIM调制方式的频谱特性只需要比较窄的通频带便可以实现数据传输,适合作为该窄带通放大电路的数据调制方式。本文采用LED发出的可见光作为数据载体,APD作为光敏器件,STC12系列单片机作为微处理器(MCU),结合DPIM调制方式和窄带通放大电路,辅助以电源电路、下载电路、LED驱动电路等实现了可见光通信。实验测试的结果表明:该系统可以在5m直视距离内无聚光装置实现传输速率约为45.8Kb/s的单向数据传输。系统稳定性好、成本较低,具有较好的应用前景。OFDM调制方式可以实现高速的可见光数据通信,是目前的研究的热点。本文在单向可见光通信系统的设计经验和对相关资料的认真研究的基础上,设计了OFDM可见光通信系统的部分重要模块的电路原理图,对OFDM可见光通信系统的实现具有重要参考意义。
[Abstract]:The application of visible light communication technology has a broad prospect, but the technology is complex and expensive, so it still needs a lot of research. The data modulation mode has an important impact on the realization of visible light communication system. In this paper, the digital pulse interval modulation (DPIM) and the orthogonal frequency division multiplexing (OFDM) modulation are studied and compared with those in the protected time slot, the unprotected time slot and the positive polarity modulation in the visible light communication. The relations among symbol structure, average transmit power, bandwidth requirement of DPIM modulation with different order in many cases of negative polarity modulation are discussed. The realization principle of OFDM modulation mode is studied. The selection basis of important parameters of OFDM modulation is given. The realization of visible light communication system using LED and avalanche photodiode is the mainstream scheme to realize visible light communication at present. The modulating characteristic of LED is analyzed and studied in this paper. Performance is used to guide the design of LED drive circuit. Based on the study of APD temperature characteristics, a practical APD power supply circuit is designed to ensure the stability of APD gain. The amplifier circuit generally has a fixed bandwidth gain product. Therefore, narrowband pass amplification circuit can simplify the system, improve the signal gain, and filter the noise and clutter of the low frequency power supply better with smaller bandwidth. In this paper, a unidirectional visible light communication system is developed by using simple components to form narrowband pass amplification circuit. The spectrum characteristics of first-order DPIM modulation are analyzed and studied. Only narrow bandwidth is required for the spectrum characteristics of first-order DPIM modulation. Can achieve data transmission, It is suitable for the data modulation of the narrowband pass amplifier circuit. In this paper, the visible light emitted by LED is used as the data carrier of Guang Min device, STC12 series single chip microcomputer as microprocessor, combined with DPIM modulation mode and narrowband pass amplifier circuit. Auxiliary power supply circuit, The experiment results show that the system can transmit the unidirectional data at 45.8 KB / s within 5m direct viewing distance, and the system has good stability and low cost. OFDM modulation can realize high speed visible light data communication, which is a hot research topic at present. Based on the design experience of unidirectional visible light communication system and the study of related data, The circuit schematic diagram of some important modules of OFDM visible light communication system is designed, which has important reference significance for the realization of OFDM visible light communication system.
【学位授予单位】：江南大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN929.1

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