Prediction and removal of rotation noise in airborne EM systems

Abstract

We aim to eliminate or reduce significant impediments to conductive target detection and conductive cover penetration in airborne electromagnetic (AEM) systems. Existing limitations come from the very high noise encountered at low base frequencies, caused by rotations of vector magnetic field sensors in the Earth’s magnetic field. We use the output of tri-axial rotation-rate sensors to predict and subtract the rotation noise from rigidly coupled ARMIT magnetic field sensors. The approach is successful in reducing rotation noise by one to two orders of magnitude at low frequencies.

Limitations to conductive target detection in AEM systems come from the high noise encountered at low base frequencies, caused by rotations of vector magnetic field sensors in the Earth’s magnetic field. We use rotation-rate sensors to predict and subtract the rotation noise from rigidly coupled ARMIT magnetic field sensors.

Key words::

• airborne EM, low-frequency, motion noise, rotation noise.

Acknowledgements

Thanks to AMIRA project P1036A for permission to publish the data utilised in this study. Thanks to the ASEG for funding the purchase of the rotation-rate sensor and other project expenses through a Research Foundation Grant. Computing resources for this project came from RMIT University, with support for Terence Kratzer from an Australian Postgraduate Award. James Macnae’s contribution was funded through RMIT University. We thank two anonymous reviewers and associate editor Aaron Davis for constructive suggestions to improve the manuscript.