The Narod ring-core magnetometer used by the Geophysical Institute is manufactured by Narod Geophysics Ltd. of Canada. The magnetometer is a basic fluxgate design using a triaxial set of cores.

The sensor cores are shown here in the GI enclosure. A carefully machined ceramic block (the white block in the center) holds each of the three cores in mutually orthogonal directions. The cores are wrapped in copper wire. Two can be seen in this photo. The ceramic block is mounted to the base of an aluminum enclosure designed and manufactured at the Geophysical Institute. The blue-anodized aluminum cover encloses and seals the sensor block from the elements. The gold-anodized aluminum housing is mounted on a platform which can be leveled and oriented to any azimuth. The red cable attaches the sensors to the preamplifier (the black box on the table). From there a fifty meter length of shielded cable carries signals to the main electronics.

The magnetometer electronics are controlled by an S-100 computer that uses internal calibrations to produce digital output in units of nano Tesla. The nominal data rate is 8 samples per second. The unit also has the capability of digitizing other signals and including them in the output data stream. We use this function to include an IRIG D slow-code time signal that is generated by a GPS clock in one data channel for absolute timing.

A few of the characteristics of the Narod ring-core fluxgate system are as follows:
Temperature stability: < 0.1 nT/degree (sensor);
Long term drift: < 10 pT/day;
Noise: 7 pT/root Hz @ 1Hz;
Orthogonality error: <0.1 degree;
Digitization: 16 bits;
IEEE-696/S-100 Bus.

Further information can be obtained from Narod Geophysics Ltd., #310, 2475 York Ave., Vancouver, B.C., Canada, V6K-1C9. Tel/fax: 604-732-9083

Return to the Geophysical Institute Magnetometer Array page.