Hardware Design And Development Of High Precision Optical Time Domain Reflectometry

Since the beginning of the 21 st century,the optical fiber communication network has rapidly developed into the world's largest communication network because of its unique frequency bandwidth,wide communication capacity and low loss.It has also been widely used in the fields of electric power,aerospace,military affairs and scientific research.Optical fiber as a huge communication network transmission carrier,because of their material,the external environment and many other reasons,often lead to various types of fiber failure,resulting in communication interruption,to bring inconvenience to the people's production and life.And the optical time domain reflectometry as the most professional optical fiber fault measurement equipment,in the face of the explosive growth of the number of fiber optic links in the status of fiber in the preparation,operation,maintenance and other aspects are playing a pivotal role.However,at the same time to meet the high precision,large dynamic range,attenuation information accurate and other indicators of the OTDR price is expensive and key technology has long been in foreign manufacturers monopoly.So it is more meaningful to design a high-precision optical time domain reflectometry to meet the actual needs of the project.Based on the above requirements,this paper combines the advantages of the traditional pulse OTDR that can be achieved the characteristics of attenuation detection with the advantages of chaotic OTDR that can be achieved with distance-independent high-precision optical fiber faults detection.A high precision optical time domain reflectometry prototype based on chaotic and pulse signals is developed,reached a constant spatial resolution of 35 cm within 110 km,and the accurate attenuation information extraction of 0.184 dB / km is realized in the 54 km measurement range.Based on the development of high precision optical time domain reflectometry prototype,this paper focuses on the hardware design of the prototype module,described the following work:1.The common fiber faults and its detection method are summarized,and the present situation of optical time domain reflection technology is analyzed and compared.This paper analyzes the principle of high precision OTDR,and introduces the overall design and core module of the prototype.2.The design of the light source module of high precision OTDR is analyzed emphatically,which mainly includes the design of CPLD signal source,laser direct modulation circuit and the rest of the circuit design.Completes the debugging work of chaos,pulse electric signal and chaos and pulse laser signal.3.Based on the theoretical analysis results,the experimental results show that the optical fiber fault location,spatial resolution,dynamic range and attenuation information extraction are carried out,and the experimental results are analyzed.