Embedded Platform Designe For Long Distance Distributed Fiber Sensing System

In recent years,with the research of BOTDA(brillouin optical time domain analysis), a distributed fiber optic sensing system that based on stimulated brillouin scattering has attracted more and more attention. As research shows, BOTDA has broad application prospects in the pipeline fire alarm, submarine cable strain monitoring and other fields.The control and data acquisition tasks of the current BOTDA are usually completed by the general data acquisition card and waveform generation card. This method is not designed for the BOTDA. On the one hand, some functions are redundant and costly, on the other hand it makes the PC development complicating. This paper presents a embedded platform for the distributed optical fiber sensor system. It used the FPGA + ARM architecture and is designed for BOTDA. Control and data acquisition are realized in the same board, which improving the efficiency and reducing the costs.This paper briefly describes the characteristics and types of fiber optic sensors, and then focuses on the principles of BOTDA. The paper also describes the application of BOTDA in the long distance distributed optical fiber sensing field, and describes its four important technical indicators: measurement resolution, spatial resolution, sensing distance and measurement time. The factors that influencing these four indicators are pointed out and methods to improve are given by this paper.From the aspect of schematic and PCB board, the paper details the board-level circuit design of embedded platform, it describes the selection rules of the key chips and the ideas of circuit design via the schematic. It also describes the PCB rules from the aspects of device layout, ground plane segmentation and high speed signal traces.With the circuit board,we realize to control the devices of BOTDA and acquire the sensor information and communicate with PC.Then,this paper describes the module designs in the FPGA. For the key modules, it describes the simulation and debugging process. The noise reduction algorithm and encoder pulse generating circuit saved a large number of resources of FPGA. It also designs a reliable communication between the hardware board and the computer via FSMC. At last, we conducted a temperature and strain tests with the embedded platform by building optical systems and power systems. According to the experiments, it shows that the temperature resolution achieves ±2°C, and the strain resolution achieves ± 40 μξ.