抄録
It is shown that an induction-type, geomagnetic sensor can be simply calibrated by using it as one arm of a balanced Wheatstone bridge, and by driving the bridge with an oscillator. The theoretical development of the calibration procedure takes into account the possibility that the sensor properties are not linear and therefore the calibration procedure can be used to detect nonlinearities. The theory does not demand that the input signal be sinusoidal.
Certain sensor configurations lead to exact analytical expressions for the calibration parameters. These include the various ellipsoids of revolution, for which special cases give results for the long, slender solenoid and for the flat disc. Expressions are also obtained for air-core cylinders of finite length, but these latter expressions assume that the sensors are linear.
The theory is extended to frequencies comparable with the sensor resonance frequency, and above, for the cases in which the sensor capacity can be represented by a linear, parallel capacitor.
The configuration suggested lends itself readily to feed-back circuits, including those incorporating digital elements.
