Hitachi, Ltd.

Agency of Industrial Science and Technology

Keiko Makie

Masao Hotta

Hisashi Kado

Shinya Kuriki

A multichannel weak magnetic field measuring system for neuromagnetic diagnosis is provided having a plurality of dc-SQUID magnetometers. Bias current setting circuits are provided for detecting an even harmonic component of the output across the terminals of the corresponding SQUID and automatically adjusting a DC bias current to the SQUID. Accordingly, the level of the component becomes a predetermined value. Circuitry is also included for equalizing the magnetic flux detection sensitivities of these dc-SQUID magnetometers. Abnormal operation detecting circuits are also provided for producing abnormal operation detected outputs when the level of the corresponding even harmonic component is smaller than a certain threshold value.

Weak magnetic field measuring system using dc-SQUID magnetometer with

A digital signal weighting processing apparatus and method comprising a sampling section responsive to a measurement start signal for starting the measurement of an input signal and outputting sample values, a sample value storage section for storing these sample values in synchronism with each measurement of a single time, a weighting coefficient generation section for receiving said sample values each time the measurement of a single time is made, discriminating the magnitude of respective sample values and calculating weighting coefficients for each measurement of a single time, a weighting coefficient storage section for storing the weighting coefficients of each measurement of a single time outputted from the weighting coefficient generation section by the number of times of measurement, and a weighting section for successively reading out sample values at the same sampling time point each time the measurement of a single time is made and weighting the sample values by weighting coefficients corresponding to the number of times of measurement stored in the weighting coefficient storage section to conduct arithmetical mean operation.

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Tokyo, Japan

Keiko Makie