Title :
Positioning Error Reduction Technique Using Spectrum Reshaping for Distributed Fiber Interferometric Vibration Sensor
Author :
Xie, Shangran ; Zhang, Min ; Li, Yanhe ; Liao, Yanbiao
Author_Institution :
Dept. of Electron. Eng., Tsinghua Univ., Beijing, China
Abstract :
A novel positioning error reduction technique is proposed for dual Mach-Zehnder fiber interferometric distributed vibration sensor. The 3 dB bandwidth of the power spectrum of interference signal is broadened to reduce the mean square error (MSE) of the cross-correlation based positioning algorithm. A high-pass filter (HPF) whose cutoff frequency is larger than the upper frequency of signal 3 dB bandwidth is applied to reshape the original power spectrum by attenuating the magnitude of low-frequency mainlobe to the same order as that of the small high-frequency components. The usage of HPF can cause bandwidth broadening and signal to noise ratio (SNR) reduction, the influence of both effects on ultimate positioning MSE are analyzed in detail. Theoretical analysis shows that there exists a valid region for the cutoff frequency of the HPF within which the contribution of bandwidth broadening dominates the process. The technique is also experimentally verified and analyzed by field test on an installed submarine cable between two islands of Zhejiang Province, China. Field test results coincide with the theoretical predictions and show that a maximum of 7 dB reduction of positioning MSE can be achieved when optimal cutoff frequency of HPF is used.
Keywords :
Mach-Zehnder interferometers; distributed sensors; fibre optic sensors; high-pass filters; mean square error methods; optical cables; optical fibre filters; optical fibre testing; optical noise; spectral line broadening; HPF; MSE; SNR reduction; bandwidth broadening; cross-correlation based positioning algorithm; cutoff frequency; distributed fiber interferometric vibration sensor; dual Mach-Zehnder fiber interferometric distributed vibration sensor; field test; high-pass filter; installed submarine cable; interference signal; low-frequency mainlobe; mean square error; positioning error reduction technique; power spectrum; signal bandwidth; signal-to-noise ratio reduction; spectrum reshaping; theoretical analysis; Bandwidth; Cutoff frequency; Interference; Optical polarization; Optical sensors; Signal to noise ratio; Vibrations; Distributed vibration sensor; cross correlation; dual Mach-Zehnder interferometer; time delay estimation;
Journal_Title :
Lightwave Technology, Journal of
DOI :
10.1109/JLT.2012.2221078