An adaptive channel equalization algorithm for MFL signal

作者：Mukherjee Debmalya; Saha S; Mukhopadhyay S^*

来源：NDT & E International, 2012, 45(1): 111-119.

DOI：10.1016/j.ndteint.2011.08.011

• Magnetic flux leakage
• Adaptive filter
• Channel equalization
• Noise cancellation
• Mean absolute deviation
• Baseline estimation

Magnetic Flux Leakage (MFL) method is one of the most robust non destructive evaluation (NDE) techniques employed by in-line inspection (ILI) tools such as an instrumented pipeline inspection gauge (IPIG), to assess the health of buried cross country pipelines, carrying petroleum products. An array of hall-effect sensors disposed ideally at the magnetic neutral plane of a permanent magnet resident in IPIG, cling to the inner surface of the pipe wall, measuring the change in leakage flux density. However, ideal sensor disposition is almost never satisfied and each sensor measures differently. In this paper, a new scheme of channel equalization is proposed for MFL signal so as to correct sensor misalignments, which eventually improves accuracy of defect characterization. Also, for the above, a baseline estimator is developed, which estimates the baseline of MFL sensor output signal under pipeline defects and key features (wields, sleeves, valves). The scheme proposed is adaptive to the effects of error in the disposition of the sensor due to manufacturing imperfections and sensor movements (bounce/axial shift near a weld). The algorithm is tested on field data acquired by an IPIG running in a commercial pipeline. The final result obtained shows excellent signal recovery and noise cancellation.

• 出版日期2012-1