Target location method for pipeline pre-warning system based on HHT and time difference of arrival

The increasing serious pipeline leakage accidents are caused by third part damage. The third party damage activity around pipeline can generate seismic wave, and the seismic wave can be used for target identification and damage activity location. This paper presents a novel passive location method based on arrival time difference of specific seismic wave characteristic frequencies. The seismic signals are typically non-stationary and the conventional methods cannot analyze them well. Hilbert-Huang Transform (HHT), including empirical mode decomposition (EMD) and Hilbert transform, is a new time-frequency analysis method and can be used for seismic signals analyzing. Firstly, EMD is applied to process the signals and obtain the intrinsic mode functions (IMFs) features. The kurtosis features are used to identify targets and characteristic frequencies are selected as principal components according to IMFs energy features. These principal components are processed by windowed harmonic wavelet transform and then instantaneous features of seismic signals can be extracted. TDOA can be deduced from the arrival time difference of principal frequency components. Finally, target location can be achieved by the time difference analyzing, sensors layout and the relative position between sensors and targets. The seismic signals acquired from field experiment are analyzed and the results are discussed.