Magnetic compensation circuit and method for compensating the output of a magnetic sensor, responding to changes a first magnetic field

摘要

A solution for compensating a magnetic field sensor to permit detection of a small magnetic field in the presence of a large magnetic field is disclosed. A magnetic field sensor detects the magnetic field which produces an analogue signal then encoded by an analogue to digital converter (ADC) into a digital stream- A controller operating on the digital stream incorporates additional sensor data to Create a compensation signal which is sent to a digital to analogue (DAC) Converter. This compensation signal then modifies the output of the magnetic field sensor before entering the ADC. Compensation is software Controlled, and is thus adaptable to numerous conditions requiring compensation. Apart from being easily tunable, the compensation may respond dynamically to changing conditions. The invention has particular application to airborne electromagnetic surveying where small fields scattered from the Earth are measured in the presence of a large transmitted field.