基于FPGA的分布式光纤测振仪设计

发布时间：2018-01-07 07:24

本文关键词：基于FPGA的分布式光纤测振仪设计　出处：《太原理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：振动信号检测通常采用点式分离的传感器作为信号采集装置,这类方法对机械设备故障检测具有良好效果,但不适用于长距离分布式的振动测量。相位敏感光时域反射(Φ-OTDR)技术作为一种分布式振动信号检测的新型方案,克服了上述的不足,在振动领域应用广泛。在实际工程中,振动信号的快速性和瞬时性对数据采集速率和数据传输速度提出了较高的要求。FPGA由于并行运行快、灵活度高和高速处理等优点,常用于信号的高速采集,将FPGA技术应用于分布式光纤振动传感系统中,实现信号的高速处理与振动事件的实时定位和解调很有必要。为了实现对振动事件的实时定位和解调,本文设计并实现了基于FPGA的分布式光纤测振仪。整个测振系统分为三部分:分布式光学测振平台、高速数据采集系统和上位机监控软件。其中分布式光学测振平台作为系统的第一部分,实现了由外界振动信号向光信号的转化,然后通过光电转换为电信号。高速数据采集系统作为系统的中间层,将光电转换器输出的模拟信号转换为数字信号并进行数据处理,再将数据传输给上位机。上位机监控软件将接收到的数据配合设计的算法程序,将结果输出,提供了整个系统的控制和数据显示功能。主要的研究内容如下:首先,从振动信号对光相位的调制以及通过检测光相位引起的光强变化来实现对振动信号的解调,阐述了振动检测的基本原理,根据指标要求进行了器件的选型并设计了基于振动检测原理的分布式光纤振动检测系统的方案,搭建了Φ-OTDR分布式振动检测的光学平台。采用示波器捕获光学平台的后向瑞利散射信号并结合Matlab,对后向散射曲线进行了分析,初步验证了系统能够成功对振动事件检测和解调。接着,基于AD9226芯片和Altera的FPGA芯片设计了高速数据采集系统:首先确定了整体的数据采集方案,设计了外围衰减电路和传输电路;然后,提出了两种数据采集方案,一种基于串口传输的单点数据采集方案:一种基于USB2.0传输的连续数据采集方案,详细阐述了USB2.0、CY7C68013A以及Slave FIFO的基本原理和数据的读写时序等,建立对应采集模型,并将采集系统结合光学平台对光纤沿线分布式实时采集进行了验证;研究MFC的程序开发框架和系统的可视化需求,设计了上位机监控界面的总体方案,对主要功能模块以及软件实现代码进行了具体说明,包括参数设置、数据处理、信号显示等单元,实现了实时数据显示与存储功能。最后,建立了完整的分布式振动测量系统,并通过实验进行验证。实验结果表明:系统能够在11.5km的传感范围上实现20m的定位误差和30m的空间分辨率,频率响应线性度良好,响应时间快,各个指标均满足项目的要求,系统同时还能响应正弦波、方波和冲击信号,特征鲜明,效果显著。
[Abstract]:The vibration signal detection sensor is usually used as the separation point signal acquisition device, this method has a good effect on the mechanical equipment fault detection, vibration measurement but not suitable for long distance distributed. The phase sensitive optical time domain reflectometry (-OTDR) technology as a new scheme of a distributed vibration signal detection, overcomes the lack of vibration widely in application. In practical engineering, rapid and transient characteristic of vibration signal is put forward higher requirements because of the parallel operation of.FPGA fast speed data acquisition and data transmission speed, has the advantages of high flexibility and high processing speed, high speed data acquisition is used to signal, the application of FPGA technology in distributed optical fiber vibration the sensing system, it is necessary to real-time positioning and high-speed demodulation processing and vibration signals of the event. In order to realize the real-time positioning and demodulation of the vibration of the event. The design and implementation of distributed optical fiber vibrometer based on FPGA. The whole vibration system is divided into three parts: distributed optical measurement platform, high speed data acquisition system and PC monitoring software. The distributed optical measurement platform as the first part of the system, the signal into optical signal by external vibration, and then converted to electrical signals through the photoelectric. High speed data acquisition system as the middle layer of the system, converting the analog signal into a digital signal output of photoelectric conversion and data processing, then transmits the data to the host computer. The PC monitoring software will receive the data with the design of the algorithm, the results output, provides a control and data of the whole system the display function. The main contents are as follows: firstly, the vibration signal of the optical phase modulation and phase detection caused by light intensity changes will come true Demodulation of the vibration signal, expounds the basic principle of vibration detection, according to the requirements of the device selection and design of distributed optical fiber vibration detection system of vibration detection scheme based on the principle, establishes the optical platform with -OTDR distributed vibration detection. Using the oscilloscope to capture optical platform Rayleigh backscattering signals combined with Matlab and on the back scattering curves were analyzed, proves that the system can successfully detect and demodulate the vibration events. Then, the design of FPGA high speed data acquisition system based on Altera chip and AD9226 chip: first determine the overall design scheme of data acquisition, the peripheral circuit attenuation and transmission circuit; then, put forward two the data acquisition scheme, a scheme of single point data acquisition serial transmission based on a continuous data acquisition scheme based on USB2.0 transmission, elaborated USB2.0, CY 7C68013A and the basic principle and data Slave FIFO read and write timing, establish corresponding acquisition model and acquisition system with optical platform along the fiber distributed real-time acquisition was verified; visualization application development framework and system of MFC, overall design of the PC monitoring interface, the main function module and the software realization of the code in detail, including parameter setting, data processing, signal display unit, to achieve real-time data display and storage functions. Finally, a distributed vibration measurement system, and verified by experiments. The experimental results show that the spatial resolution of the system can realize the positioning error and 30m 20m in the sensing range 11.5km on the frequency response, good linearity, fast response time, all indexes meet the requirements of the project, but also in response to sinusoidal system Wave, square wave and shock signal are characterized by distinctive features and remarkable effect.

【学位授予单位】：太原理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN791;TP274

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