"EMI and Magnetometer Joint Sensing Data"

"This paper presents a sensing approach which can be utilized for sensing deeply buried targets, as well as both ferrous and non-ferrous ones, utilizing a magnetometer paired with a time-domain electromagnetic induction (TDEMI) system. Detecting subsurface targets of interest (TOIs) such as munitions and explosives of concern (MEC), buried infrastructure, and even mineral and ore deposits, necessitate different sensing approaches due to their widely ranging sizes, depths, and material compositions. Since most TOIs contain metallic components, electromagnetic induction (EMI) and magnetometry are common approaches for detection and discrimination. However, both of these sensing modalities have drawbacks: magnetometers are passive sensors, detecting ferromagnetic objects through their perturbation of Earth\u2019s magnetic field. Magnetometers can have high sensitivity which allow for discerning small-magnitude perturbations, but magnetometer data provide limited information regarding material properties of the target. TDEMI sensors, by contrast, are active systems which can detect the secondary field from conducting targets induced by the time-varying primary magnetic field of the sensor. However, the detection of the secondary field response is made difficult by both the signal\u2019s spatial decay (as dictated by the physical limitations of induced dipoles) and temporal characteristics (as dictated by sensor noise and target electrical properties). This paper investigates a combination of active EMI and rapidly sampled magnetometry to investigate the feasibility of extracting late-time induced magnetic field responses from MEC, as well as specifically detecting non-ferrous targets with a magnetometer. A test setup was established to conduct repeatable and reliable data collection with a variety of targets, varying geometries, testing different target material compositions. Target parameters were chosen to facilitate comparative simulations and modeling. Lab data was subsequently collected, comparing both sensing modalities against each other, as well as different targets\u2019 responses. Finally, simulation modelling was compared to the experimental data to verify that the observed data agreed with expectations. The data indicate that using a magnetometer in conjunction with a TDEMI system allows for deeper target differentiation, as well as sensing of non-ferrous materials with a magnetometer."