Title :
Adaptive cancellation of line-frequency noise in magnetocardiogram measurements
Author :
Washio, T. ; Kuriki, S. ; Fujita, M. ; Hayashi, A.
Author_Institution :
Res. Inst. for Electron. Sci., Hokkaido Univ., Sapporo, Japan
Abstract :
In the recording of magnetocardiogram (MCG), the largest environmental magnetic field interference is the line-frequency noise. Even with multi p-metal layer shielding, 50 or 60 Hz interference is not completely rejected. In this paper, we report an extension of active noise cancellation to the magnetic field interference, in which a digital signal processor (DSP) was used. A sinusoidal wave generated in the DSP was filtered adaptively in the least mean square algorithm, and its output was supplied as cancellation field by means of a coil that was wound around a small room magnetically shielded with a single g-metal wall. With the help of the low-frequency noise compensation, which was also applied to the shielded room, wide band MCG recording was possible inside the room using a high temperature superconducting quantum interference device.
Keywords :
SQUID magnetometers; active noise control; adaptive signal processing; magnetocardiography; medical signal processing; 50 Hz; 60 Hz; adaptive cancellation; cancellation field; coil; high temperature superconducting quantum interference device; least mean square algorithm; magnetically shielded small room; multi p-metal layer shielding; shielded room; single g-metal wall; wide band MCG recording; Interference; Magnetic field measurement; Magnetic noise; Magnetic recording; Magnetic shielding; Noise cancellation; Noise measurement; Superconducting device noise; Superconducting magnets; Working environment noise;
Conference_Titel :
Engineering in Medicine and Biology Society, 2001. Proceedings of the 23rd Annual International Conference of the IEEE
Print_ISBN :
0-7803-7211-5
DOI :
10.1109/IEMBS.2001.1017204
