Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2016 Mar 4;16(3):323.
doi: 10.3390/s16030323.

SVD-Based Technique for Interference Cancellation and Noise Reduction in NMR Measurement of Time-Dependent Magnetic Fields

Wenjun Chen  1 , Hong Ma  2 , De Yu  3 , Hua Zhang  4
Affiliations

SVD-Based Technique for Interference Cancellation and Noise Reduction in NMR Measurement of Time-Dependent Magnetic Fields

Wenjun Chen et al. Sensors (Basel). .

Abstract

A nuclear magnetic resonance (NMR) experiment for measurement of time-dependent magnetic fields was introduced. To improve the signal-to-interference-plus-noise ratio (SINR) of NMR data, a new method for interference cancellation and noise reduction (ICNR) based on singular value decomposition (SVD) was proposed. The singular values corresponding to the radio frequency interference (RFI) signal were identified in terms of the correlation between the FID data and the reference data, and then the RFI and noise were suppressed by setting the corresponding singular values to zero. The validity of the algorithm was verified by processing the measured NMR data. The results indicated that, this method has a significantly suppression of RFI and random noise, and can well preserve the FID signal. At present, the major limitation of the proposed SVD-based ICNR technique is that the threshold value for interference cancellation needs to be manually selected. Finally, the inversion waveform of the applied alternating magnetic field was given by fitting the processed experimental data.

Keywords: interference cancellation; magnetic field measurement; noise reduction; singular value decomposition; time-dependent magnetic fields.

PubMed Disclaimer

Figures

Figure 1
Figure 1
Schematic diagram of the NMR system, all gray parts are controlled by PXI-6773.
Figure 2
Figure 2
Sketch of the pulse sequence and the data selection.
Figure 3
Figure 3
NMR data processing flow chart. The demodulation frequency is 24.65 MHz. The pass band of the digital low pass filter is 0–600 kHz, and the cutoff frequency is 1 MHz.
Figure 4
Figure 4
Spectrum of one FID data set of a low SIR. The data has been pre-processed (demodulation, low pass filtering and extraction). The FID signal peak is marked; others are RFI peaks. Obviously, the spectral width of the FID signal is broader than that of RFI.
Figure 5
Figure 5
Schematic overview of the ICNR algorithm based on singular value decomposition.
Figure 6
Figure 6
Fourier amplitude spectra of (A) the FID data; (B) the corresponding reference data; and various spectra after interference cancellation with different threshold value (C) kin = 0.4; (D) kin = 0.5; (E) kin = 0.6; (F) kin = 0.7, respectively.
Figure 7
Figure 7
The effect of interference cancellation and noise suppression. The spectra of (A) the raw FID data; (B) the reference data; (C) the FID data after interference cancellation with a threshold value of 0.5; (D) noise suppression by preserving only the largest one of the remaining singular values.
Figure 8
Figure 8
Singular value plots of Figure 7A–C. The marked singular value corresponds to Figure 7D.
Figure 9
Figure 9
The waveforms of raw FID data (cyan), and the data after interference cancellation (blue) and noise suppression (red).
Figure 10
Figure 10
The waterfall graph of all 29 NMR spectra.
Figure 11
Figure 11
Fitting curve of the alternating magnetic field when the operating voltage is 250 V and residual error.
See this image and copyright information in PMC

References

    1. Haase J. First 2H NMR at 58 T. Appl. Magn. Reson. 2004;27:297–302. doi: 10.1007/BF03166323. - DOI
    1. Zheng G.-Q., Katayama K., Kandatsu M., Nishihagi N., Kimura S., Hagiwara M., Kindo K. 59Co NMR at Pulsed High Magnetic Fields. J. Low Temp. Phys. 2010;159:280–283. doi: 10.1007/s10909-009-0130-6. - DOI
    1. Abou-Hamad E., Bontemps P., Rikken G. NMR in pulsed magnetic field. Solid State Nucl. Magn. Reson. 2011;40:42–44. doi: 10.1016/j.ssnmr.2011.06.002. - DOI - PubMed
    1. Pei S., Tseng C.-C. Elimination of AC interference in electrocardiogram using IIR notch filter with transient suppression. IEEE Trans. Biomed. Eng. 1995;42:1128–1132. - PubMed
    1. Dalgaard E., Auken E., Larsen J.J. Adaptive noise cancelling of multichannel magnetic resonance sounding signals. Geophys. J. Int. 2012;191:88–100. doi: 10.1111/j.1365-246X.2012.05618.x. - DOI

Publication types

LinkOut - more resources