Compensation of the full magnetic tensor gradient signal

Abstract

In recent developments a full tensor magnetic gradient system has been deployed in South Africa. The instrument is made by IPHT (Institute of Photonic Technology, Jena, Germany) and flown by helicopter. In developing a ?custom? solution for taking the raw signal through to a final located geophysically sound data base, one of the biggest challenges has proven to be the compensation of aircraft / bird rotational movements, so that the reported magnetic curvature gradients in the world co-ordinate system are as free of these rotational errors as possible. Issues that arise include drift correction of the Euler Angles from the INS (Inertial Navigation System), removal of flux jumps from the SQUID and recovering the three components of the ?B? field. Compensation issues are limiting the achievable resolution of the field gradients. A novel least-squares rotational adjustment of the tensor signal in a moving window is proposed as an extra compensation step to achieve higher spatial coherency of the curvature gradients.