Eddy current compensation by adaptive pre-emphasis control for NMR tomography and spectroscopy

0205358 - UPT-D 20000004 RIV CZ eng J - Journal Article
Bartušek, Karel - Jílek, Blahoslav
Eddy current compensation by adaptive pre-emphasis control for NMR tomography and spectroscopy.
Journal of Electrical Engineering - Elektrotechnický časopis. Roč. 46, č. 10 (1995), s. 339-344. ISSN 1335-3632. E-ISSN 1339-309X
R&D Projects: GA AV ČR IAA265401; GA ČR GA303/94/1236
Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

This paper reports a method of adjusting parameters of a pre-emphasis filter for eddy current compensation using a process based on adaptive signal processing. The basis of the technique is the measurement of the time dependence of the gradient field. This is directly proportional to the instantaneous frequency obtained by taking the derivative of the time dependent phase of the out-of phase component of the recorded Free Induction Decay. The derived gradient shape is made to fit the input gradient current shape through an iterative process involving minimizing the difference between the input and derived shape through adjustment of the parameters of the pre-emphasis filter. The method was verified by pre-emphasis compensation of the gradient system on a home-built 200 MHz spectrometer with a superconducting magnet.
Permanent Link: http://hdl.handle.net/11104/0100972