Pipeline security is very important in oil and gas transportation. Traditional technology such as negative pressure wave detection, acoustic detection doesn’t match the need of pre-alarm. A fiber-optic distributed vibration sensor (FDVS) is proposed and investigated. It is found that the FDVS has the advantages of long sensing distance, high spatial resolution, high sensitivity, high reliability, etc. According to calculating the time delay of the two MZIs , the vibration can be located.

A Mach-Zehnder interferometer based fiber-optic distributed disturbance sensor (FDDS) incorporating a modified phase generation carrier (PGC) is proposed and investigated. It is found that the slow time-varying fluctuation such as temperature variation causes the location errors. By employing a modified PGC technique that satisfies the requirements including high sampling frequency and compensation of the time delay from the long length fiber, the location errors caused by the slow time-varying fluctuation can be eliminated.