%0 Journal Article
%A Huang, Xiaolei
%A Dong, Hui
%A Tao, Quan
%A Yu, Mengmeng
%A Li, Yongqiang
%A Rong, Liangliang
%A Krause, Hans-Joachim
%A Offenhäusser, Andreas
%A Xie, Xiaoming
%T Sensor Configuration and Algorithms for Power-Line Interference Suppression in Low Field Nuclear Magnetic Resonance
%J Sensors
%V 19
%N 16
%@ 1424-8220
%C Basel
%I MDPI
%M FZJ-2019-04248
%P 3566 -
%D 2019
%X Low field (LF) nuclear magnetic resonance (NMR) shows potential advantages to study pure heteronuclear J-coupling and observe the fine structure of matter. Power-line harmonics interferences and fixed-frequency noise peaks might introduce discrete noise peaks into the LF-NMR spectrum in an open environment or in a conductively shielded room, which might disturb J-coupling spectra of matter recorded at LF. In this paper, we describe a multi-channel sensor configuration of superconducting quantum interference devices, and measure the multiple peaks of the 2,2,2-trifluoroethanol J-coupling spectrum. For the case of low signal to noise ratio (SNR) < 1, we suggest two noise suppression algorithms using discrete wavelet analysis (DWA), combined with either least squares method (LSM) or gradient descent (GD). The de-noising methods are based on spatial correlation of the interferences among the superconducting sensors, and are experimentally demonstrated. The DWA-LSM algorithm shows a significant effect in the noise reduction and recovers SNR > 1 for most of the signal peaks. The DWA-GD algorithm improves the SNR further, but takes more computational time. Depending on whether the accuracy or the speed of the de-noising process is more important in LF-NMR applications, the choice of algorithm should be made
%F PUB:(DE-HGF)16
%9 Journal Article
%$ pmid:31443310
%U <Go to ISI:>//WOS:000484407200123
%R 10.3390/s19163566
%U https://juser.fz-juelich.de/record/864467