【作者】 刘锐；

【导师】 吴重庆；

【作者基本信息】 北京交通大学 ， 通信与信息系统， 2009， 硕士

【摘要】 甲烷是矿井瓦斯气体的主要成分,约占83%～89%,是常见的易燃易爆气体。由瓦斯气体造成的事故已经成为煤矿安全的第一杀手,这给国民经济、矿工的人身安全造成的巨大损失,因此加强对瓦斯的监测监控,是煤矿安全生产工作的重中之重。光纤传感器由于具有灵敏度高、抗电磁干扰、耐腐蚀、电绝缘性好、便于组成遥测网络、结构简单、体积小、重量轻、耗电少等优点,越来越受到国内外广泛的重视和应用。目前国内光纤甲烷传感器都还处在实验室阶段,离实际应用还有很大的距离,稳定性、灵敏度和监测点数都有待提高。本文提出了一种基于全光缓存器光纤瓦斯传感系统的数字接收部分电路,能够与模拟接收部分配合工作达到多点监测的目的。根据拟接收波长是1665nm,带宽是155Mb/s,且以包含3个帧的数据包为单位的数字突发信号的特点,设计出的数字接收部分包括五个单元:光电转换、主放大、数字恢复、串并转换、地址识别。本文对设计的各单元的工作原理和设计方案都进行了详细的阐述。在光电转换设计中,采用了差分结构,其中光电二极管PIN是整个接收部分的关键器件,直接决定着接收信号的带宽特性和噪声特性;在主放大设计中,创新性的使用三运放差分放大电路,具有高输入阻抗和高共模抑制比等优点,降低了对运放的要求。本文还详尽介绍了各单元选择的元器件的性能指标,而且绘制和调试了数字光接收电路,实现了部分电路功能,通过观察信号上升时间可知光电二极管PIN所能接收数字激光信号的带宽。本文还对多址光源信号进行了设计,给出了信号源数据包的帧格式和编码思想;并且使用QuartusⅡ在Verilog HDL硬件描述语言和现场可编程逻辑器件FPGA的基础上设计和仿真了地址识别单元,对帧头地址序列进行检测,发出控制信号,来控制模拟接收部分截驭对应帧头地址的记录各点气体浓度信息的帧数据部分,以达到在同一光纤路径上对多个测量点进行监测的目的。更多还原

【Abstract】 Methane is a common explosive gas and the main component of marsh gas, accounting for about 83%～89%. The accident caused by marsh gas has been the first killer of coal mine safety and caused a great loss to the national economy and the safety of miners, so strengthening the gas supervision is top priority of coal mine safety production. Optical fiber sensor with advantages of high sensitivity, simple structure, anti-electromagnetic interference, corrosion resistance, good electrical insulation, facilitating remote network component, small size, light weight, low power consumption and so on, is drawing more attention and being applicated widely by domestic and abroad. Now the fiber-optic methane gas sensors are still in the laboratory stage in domestic, a long distance from practical application. Moreover, stability, sensitivity and monitoring points are yet to be improved.In this paper, a digital receiver of fiber-optic methane gas sensor system based on all-optical buffer is proposed, which can work with the analog receiver part to achieve the purpose of multi-point monitoring. Because digital burst signal’s wavelength is 1665nm, bandwidth is 155Mb/s, and every packet includes three frames, the design of the digital receiver consists of five modules: photoelectric conversion, the main amplification, digit restoration, serial to parallel conversion, and address recognition. In this paper, the principle and the design of every unit are described in detail. The design of photoelectric conversion adopts differential structure, and the key part of the digital receiver is PIN, which directly determines the characteristics of bandwidth and noise of received signal. In the main amplification design, differential three amplifiers with advantages of high input impedance and high common-mode rejection ratio are used innovatively, which can reduce the requirements of the amplifier. This article includes not only detailed descriptions of performance indications of the components of every unit, but also drawing and debugging of the circuit board of the digital receiver, and achieves function of parts of circuit. We can conclude signal bandwidth by observing the signal rise time. This paper also designs signals of multi-address light source, gives design of packet frame format and coding theory, and designs and simulates the address identification unit with QuartusII based on Verilog HDL and FPGA in order to achieve frame header address sequence detection and give a signal to control analog receiver the interception of data information part of the frame corresponding to frame header to achieve the purpose of multi-point monitoring in the same optical path.更多还原