Abstract: An improved signal demodulated method based on phase-sensitive OTDR system was proposed. Firstly, it illustrated the principle of this method theoretically. Then, the effect of the values of key parameters (average time, moving window, substracting interval) on the result of signal processing of the phase-sensitive OTDR system is analyzed and the guidance to determine the values of these key parameters is summarized. Lastly, compared with the conventional digital average method, the disturbance signal is was effectively demodulated with this method processing datas, which illustrated the feasibility of this method further. The result shows that this method increases the correlation of each group datas with dividing original datas into groups as the fluctuation characteristics of signals, thus improving the SNR of system obviously. This method has guidance to optimize the performance of long distance phase-sensitive OTDR to some extent.

Key words: fiber and waveguide optics, phase-sensitive OTDR, digital average, moving window, substracting interval