【作者】 贾俊；

【导师】 娄淑琴； 刘艳；

【作者基本信息】 北京交通大学 ， 通信与信息系统， 2008， 硕士

【摘要】 Sagnac干涉型光纤传感器是光纤传感器中光相位调制型传感器,多用于物理旋转状态的测量,也用于时变信号的测量。基于Sagnac干涉仪设计的光纤陀螺仪已被广泛应用于军事及商业上。基于Sagnac干涉仪的光纤传感器在长距离、小泄露管道检测定位上有其明显的优势,同时也可应用在光纤围栏报警系统中,具有简单高效、安装便捷、维护简单、成本较低等优点。本文在介绍了光纤传感器理论及技术和数据采集系统知识的基础上,主要针对Sagnac干涉仪原理以及Sagnac干涉仪单点定位原理及实验进行研究,得到了一些有效的信号分析处理方法。获得的主要研究成果有:(1)研究了Sagnac干涉原理,推导出了光在折射率为n的光路中传播时,萨格纳克效应产生的相位差与旋转角速度间关系。(2)研究了基于虚拟仪器和PCI总线的数据采集系统。掌握了PCI-1714数据采集卡的使用方法,并利用LabVIEW语言进行了数据采集程序的编写。(3)进行了Sagnac干涉仪单点干扰实验研究,采集实验中的传感信号,并对所采集信号进行分析、处理,研究了其定位实现原理,并对定位误差进行分析。介绍了基于Sagnac干涉仪的传感系统在光纤围栏报警中的应用以及管道泄漏检测定位中的应用,对其存在的问题进行了分析及探讨。(4)研究了Sagnac干涉仪单点干扰实验数据的频谱处理方法。利用小波分析法获取频谱的近似部分,以获得零频点分辨率较好的频谱。(5)研究了从Sagnac干涉仪单点干扰实验数据中获取零频值的方法。提出了一种获取零频值的新方法,并进行编程实现,实现了干扰源定位的信号分析处理的关键步骤,该方法可推广到较广的应用范围。更多还原

【Abstract】 Optical fiber Sagnac sensors are optical phase-modulated fiber sensors and have been used to measure the physical parameters such as angular velocity and time-varying signals. Fiber-Optic Gyroscope based on Sagnac Interferometers has been applied in military affairs and business. Optical fiber Sagnac sensors have a lot of advantages, such as easy installation, simple maintenance and lower costs, and have been applied in perimeter security system, pipeline leakage detection and location system.In this dissertation, firstly the theory and technology of optical fiber sensing system as well as the technologies of data acquisition system have been introduced. Then the principle of Sagnac Interferometer and the position determination experiment of disturbance in Sagnac Interferometer are studied. Some useful conclusions have been achieved. The primary achievements are as follows:(1) The principle of Sagnac Interferometer is studied. The relationship between the phase and angular velocity of rotation is obtained as a result of Sagnac Effect, when the light propagates in the optical path where the optical refractive index is n.(2) The data acquisition system which is based on Virtual Instrument and PCI bus technology is studied. Advantech PCI-1714 is used as the hardware platform of the system. The data acquisition program is developed with LabVIEW in order to drive the PCI-1714 and acquire sensing signal.(3) The position determining experiment of disturbance at a particular place along a Sagnac Interferometer is made. After the experiment, the acquired data is analyzed in order to monitor and locate the position of disturbance. The error between the theoretical result and numerical analysis result is analyzed. In the meantime, the problems which would be encountered in practical applications are discussed.(4) The method of spectrum processing of the acquired data is studied. The approximate part of the spectrum can be achieved by the method of discrete wavelet transform so that better resolution of the spectrum can be got.(5) The method to achieve the null frequency of the acquired data spectrum during the process of signal processing is studied. A new way to get the null frequency has been proposed and implemented by programming, which is the key step in the whole process of signal processing. And this method can also be used to a wider range of applications.更多还原