טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentKravzov Hila
SubjectRobust Detection of Buried Conducting Wires
DepartmentDepartment of Electrical Engineering
Supervisor Professor Moshe Nazarathy
Full Thesis textFull thesis text - English Version


Abstract

In many practical scenarios there is a need to detect and estimate the location of a buried conducting wire. In this work, we develop signal processing algorithms for estimating the position of buried conductors carrying a native or induced current based on magnetic induction measurements on the earth’s surface. We also establish improved magnetic induction measurements and signal processing methods relative to the existing methods. The derived estimator is based on the maximum-likelihood estimation method. The novel maximum likelihood method was initially tested with the conventional gradiometer (differential) measurement method. The gradiometer measurement method is based on subtracting measurements from two static wires that are relatively close to each other and located on the earth’s surface. Gradiometer measurements using the aforementioned estimation method has been shown to be sufficiently sensitive as well as relatively computationally efficient, due to the leveraging of the horizontal spatial-shift invariance quality of the problem (with respect to the magnetic field simplified expression that was used). Our algorithm yields a reasonably accurate joint estimate of lateral displacement, depth and carried current in the buried conductor. Furthermore, we propose a novel measurement setup alternative to the existing gradiometer method. This novel measurement setup will be henceforth referred to as the Large Span Differential method. The proposed measurement method is based on subtracting measurements from two wires; one wire remain static while the other wire gradually moves apart from the first wire. The novel Large Span Differential method was demonstrated analytically as well as by means of simulation. Thus, this measurement method, in conjunction with an adaptation of our maximum- likelihood estimation algorithm, improves the detection of lateral displacement, depth and carried current sensitivity by about two orders of magnitude, yielding high spatial accuracy with a relatively low signal to noise ratio.