A double-ended Raman temperature measurement method for hazardous chemicals warehouse

An adaptive calibration method for distributed temperature sensor is proposed to eliminate the influence of fiber attenuation and APD dark current fluctuation. The two ends of one fiber are connected to the different measuring channels of the system. In a measurement period, two measuring channel alternately inject pulse signal into optical fiber. With the help of the measured data obtained from the two channels, the attenuation function part in demodulation formula which is a function related to the distance is converted to a constant. The mean filtering method is used to restrain the influence of APD output fluctuation on the measurement results. The experiment shows that compared with the traditional adaptive demodulation method, the temperature measurement curve is smoother and the error is reduced from about 1 °C to less than 0.5 °C.