Software

RECORDING

For all data acquisition and MEG system control and maintenance, we use the MEG laboratory software MEG160. This software is produced jointly by Yokogawa Electric Corp., Eagle Technology Corp., and the Kanazawa Institute of Technology (KIT). The principal author of the software has been Yasuhiro Haruta, of Yokogawa Electric Corp.

NOISE REDUCTION

For offline noise reduction using the three reference magnetometers, we employ the MEG laboratory software MEG160 (see Software/Recording), which uses algorithms developed at the Applied Electronics Laboratory at KIT, and specifically the Continuously Adjusted Least-Squares Method (CALM). This noise reduction procedure essentially eliminates any correlation that the data from the MEG sensors might have with any of the three reference magnetometers by removing any detected covariance. This is performed data point by data point, with a moving window typically of six seconds, such that for each data point the three seconds of data before and the three seconds of data after are used to determine the covariance. This process was designed to eliminate low frequency (<10Hz) noise at Keio University in Tokyo, Japan, where a KIT MEG machine is also located. There, as here in New York, large extramural magnetic noise from passing trains/subways can greatly disrupt MEG sensors.