The Positioning Algorithm Based On Fiber Optic Vibration Safety Warning System Research

Oil and natural gas pipeline transportation play a more and more increasingly important role for social energy demand and daily life. The present security protection for long-distance pipeline is not only complex but also inefficient. The pipeline fiber-optic pre-warning system based on Mach-Zender interference principle makes a vibration test on the fiber optic cable accompanied by pipeline, then carry out the detection, positioning, sorting, blending and identification to the vibration signal, among which the positioning to the potential hazards of vibration source is one of the key technologies of pre-warning system. This research makes a profound study on the positioning method, positioning accuracy and fused positioning method.When the homologous signals reach the receiver, since correlation exists between the two signals, time differences of vibration signal arrived can be estimated according to their cross-correlation functional peak points, based on which the position of vibration source can be estimated. Through the analyses and comparison between various methods of positioning on time difference, this research adopts the generalized cross-correlation to estimate the position of vibration source. What’s more, this research proposes the adoption of iterative interpolation algorithm based on cosine interpolation to enhance the positional accuracy, and interpolates the correlation peak to achieve a higher accuracy to time delay estimation.After the positioning value of the time delay estimation is obtained, the relation between correlation coefficient and SNR is deduced. Furthermore, combined with the CLRB lower bound, which is used to measure the error of time delay estimation, this research raises two positioning accuracy formula that comply with the experimental environment of this research. The two formulas are used to measure the positioning accuracy under the same and different SNR of frequency point. What’s more, the meanings of the formula are verified from both theoretical and practical perspectives.At last, the fusion positioning for concurrent events is carried out, which improves the accuracy of positioning value.