CPC G01R 33/0017 (2013.01) [G01D 5/142 (2013.01); G01D 18/00 (2013.01); G01R 33/0041 (2013.01); G01R 33/07 (2013.01); G01R 35/00 (2013.01)] | 14 Claims |
1. A field-gradient sensor device comprising:
a reference field sensor providing a reference sensor signal in response to a field,
a calibrated field sensor providing a calibrated sensor signal in response to the field,
a reference circuit connected to the reference field sensor and adapted to receive a reference signal,
an adjustable circuit connected to the calibrated field sensor and adapted to receive a calibrated signal,
wherein, when the adjustable circuit is adjusted with the calibrated signal, said calibrated signal being different from the reference signal, the calibrated field sensor provides a calibrated sensor signal substantially equal to the reference sensor signal,
wherein said field-gradient sensor device is arranged to determine a difference signal or gradient signal based on the reference sensor signal and the calibrated sensor signal.
|