SQUID gradiometry for magnetocardiography using different noise cancellation techniques

Citation
M. Bick et al., SQUID gradiometry for magnetocardiography using different noise cancellation techniques, IEEE APPL S, 11(1), 2001, pp. 673-676
Citations number
12
Categorie Soggetti
Apllied Physucs/Condensed Matter/Materiales Science
Journal title
IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY
ISSN journal
10518223 → ACNP
Volume
11
Issue
1
Year of publication
2001
Part
1
Pages
673 - 676
Database
ISI
SICI code
1051-8223(200103)11:1<673:SGFMUD>2.0.ZU;2-5
Abstract
Magnetocardiographic (MCG) measurements in unshielded environment require e fficient noise cancellation techniques. We have applied two software gradio metry methods to analyze the time series of signal and reference data recor ded outside magnetic shielding with high temperature superconducting quantu m interference device (HTS SQUID) based gradiometers. One method uses adapt ive frequency dependent gradiometer coefficients determined in the Fourier domain to subtract the reference from the signal data. The other method com bines recently developed techniques for nonlinear projection with propertie s of the wavelet transform to extract noise in state space. The analyzed MC G data sets showed improved signal-to-noise ratios for both methods as comp ared to the data recorded with the electronic gradiometer. In this way, it is possible to increase the bandwidth from 130 Hz for our electronic gradio meter to 250 Hz without using any additional filtering.