Magnetic detection of a surface ship by an airborne LTS SQUID MAD

A three-axis LTS SQUID magnetometer was fabricated as a Magnetic Anomaly Detector (MAD) onboard an aircraft. A magnetometer measuring magnetic total field, which is rotational invariant, is suitable for performing distant target detection in unshielded mobile operation. To configure the magnetometer, several requirements for the SQUID magnetometer had to be considered such as ultra wide dynamic range above 150 dB, extremely accurate linearity and orthogonality of the three-axis. The magnetic vector component with the sufficient dynamic range was obtained by synthesizing the SQUID output voltage and the counts of SQUID´s flux-voltage (Φ-v) periodicity. The magnetic total field was obtained from the three magnetic vector components using our scalar composition algorithm that corrects the non-orthogonality and so on. The compensation algorithm with quadratic form of permanent, inductive and eddy-current magnetism was used to suppress the magnetic noise caused by the platform manoeuver. Our SQUID MAD was designed to implement the procedures mentioned above in real-time. The SQUID MAD was equipped in the tail boom of the aircraft and its performance was evaluated in the flight tests. We confirmed that our SQUID MAD provided extremely high sensitivity in flight by suppressing the magnetic noise, and successfully detected a distant surface ship