Technical term – magnetometry
From the surface, we can detect metal objects in the soil by measuring magnetic fields. There are two measuring principles:
- Active detectors sends out magnetic pulses and measures the response, caused by "ferro and non-ferro metal" objects, with a standard measuring range of 30 to 50 cm.
- a passive device measures the distortions in the earth’s magnetic field, caused by the presence of "ferro metal" objects in the soil, with a standard measuring range up to 3 or 4 m.
For large areas, we use a multisensor configuration, with 4 to 8 detectors on a chart, pulled over the area by quad or by hand. These are computer-aided detections with a GPS-antenna, allowing us to rapidly and accurately create a digital field map with the detected anomalies.
In combination with ground drills or cone penetration push systems, we also perform depth detections.