Page - 677 - in Book of Full Papers - Symposium Hydro Engineering

contains components at wavelengths that are different from the original signal. These shifted components contain information on the local properties of the fiber, in particular its strain and temperature. After an appropriate analysis of those signals, the system can therefore provide a calibrated strain or temperature reading at every meter along the sensing cable, as depicted on Fig. 1. Fig. 1 Fiber Optic Distributed Sensing System 2.2. DATA MANAGEMENT Direct data analysis based on distributed temperature or strain data has limitations and does not provides real-time data to the operator that often becomes overwhelmed by the amount of data he receives. It is therefore necessary to automate the data management and analysis process. The developed software displays measurement profiles, status maps of temperature or strain, evolution of the structure and events automatically recognized and logged by the monitoring system. All measurements are imported and stored into a single database and data is processed to apply calibrations and select zones of interest. Alarms are generated automatically, based on complex criteria (e.g. for leak detection). The user can than dig-down into raw data for deeper analysis, as shown in Fig. 2. 677