## 2 System
### UAVMAG System  
The UAVMAG system is tailored for high-resolution magnetic field measurements aimed at subsurface anomaly detection, such as unexploded ordnance (UXO) and geological structures. It integrates a high-sensitivity magnetometer array, RTK GPS, and a specialized UAV platform to ensure precise spatial positioning and accurate magnetic data capture. Figure 2 presents the structural layout of the UAVMAG system. To reduce platform-induced magnetic interference, the magnetometers are attached to a rigid vertical suspension boom beneath the UAV, secured with non-magnetic, non-conductive nylon connectors. This configuration minimizes magnetic noise by distancing the sensors from potential sources of interference, allowing the magnetometers to detect subsurface-related magnetic signals without significant contamination from the UAV's electronic and structural components. The suspended sensor assembly maintains a stable orientation relative to the ground during flight, enabling consistent magnetic data acquisition even as the UAV maneuvers along its flight path. The UAV follows a pre-programmed survey route with a line spacing  
Figure 2: UAVMAG structure diagram. of 0.5 m and a speed of 1 m/s, achieving high-resolution magnetic data collection across the survey grid. The magnetic sensor suite includes two high-precision magnetometers designed for capturing both scalar and vector magnetic field components. The Mag-03 MS1000 magnetometer, with a range of \(\pm 70\), \(\pm 100\), \(\pm 250\), \(\pm 500\), and \(\pm 1000\) uT, provides noise levels as low as 6-10 pT\(/\sqrt{\mathrm{Hz}}\) at 1 Hz. Its compact dimensions (\(32\times 32\times 152\) mm) and lightweight design (0.16 kg) make it ideal for UAV-based applications where weight is a constraint. Complementing this sensor is the CAS-18-VL magnetometer, which extends the measurement range to 10, 000-105, 000 nT with a noise sensitivity of 0.3 pT\(/\sqrt{\mathrm{Hz}}\) at 1 Hz. The CAS-18-VL's dimensions (53 mm in diameter and 130 mm in length) and weight (0.5 kg) make it suited for high-intensity magnetic surveys, providing a robust detection capability for a wide range of anomaly intensities. To facilitate readers in quickly understanding the specific parameters of the system, we present the technical specifications of the UAVMAG system, as shown in Table 1.  
Both magnetometers are synchronized with the UAV's RTK GPS, ensuring spatial alignment of magnetic readings with precise positional data. The RTK GPS offers centimeter-level positioning accuracy, crucial for high-resolution mapping of magnetic anomalies, and enables the integration of magnetic data with geospatial coordinates, facilitating comprehensive anomaly characterization. The data acquisition module operates at a high sampling rate of 160 Hz, capturing subtle magnetic field variations that indicate the presence of subsurface ferromagnetic materials. The acquired magnetic field signal consists of the geomagnetic field, UAV interference magnetic field, and magnetic anomaly signal. Within a small area, the geomagnetic field remains approximately stable over short periods and spatially uniform [30]. To eliminate its influence, the DC component is removed, while the UAV interference magnetic field is suppressed using the LTI model proposed by other members of our laboratory, as detailed in reference [31]. Additionally, this module includes real-time filtering capabilities to mitigate high-frequency noise and other unwanted interference. Post-processing techniques further enhance data integrity, effectively isolating target-related magnetic anomalies for accurate interpretation. In summary, the UAVMAG system integrates high-sensitivity magnetometers and precise spatial control, making it a versatile tool for detecting shallow subsurface magnetic