Fluxgate gradiometer
Definition
An instrument that measures the vertical gradient of the Earth's magnetic field using two fluxgate sensors mounted on a staff at fixed vertical separation, typically 0.5 m. The differential reading cancels regional field variation and emphasises local anomalies.
- Sensor separation
- Two fluxgate sensors mounted vertically, typically 0.5 to 1 meter apart
- Measurement type
- Vertical gradient of Earth's magnetic field
- Key advantage
- Differential reading cancels background variation while emphasizing local anomalies
Common questions
How does a fluxgate gradiometer find buried objects?+
The instrument has two magnetic sensors stacked vertically, usually 0.5 meters apart. By comparing the difference in magnetic field strength between the two sensors, it cancels out the uniform Earth's field and picks up only the local magnetic anomalies created by buried metal or disturbed soil.
Why measure the gradient instead of the total field?+
Measuring the gradient (the difference between two points) cancels regional field variation and daily drift, which would otherwise overwhelm the small signals from buried objects. This differencing technique keeps only the near-surface anomalies that actually matter for forensic surveys.
Can a fluxgate gradiometer detect any buried material?+
It works best on materials with strong magnetic properties, especially ferrous metals like iron or steel. Buried soil disturbance and certain minerals will also show up. Non-magnetic materials like glass or some plastics are largely invisible to it.
Related terms
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Explained in these topics
- Magnetometry and Earth ResistanceAn instrument that measures the vertical gradient of the Earth's magnetic field using two fluxgate sensors mounted on a staff at fixed vertical separation, typ...
- Magnetometry and Soil Magnetic SusceptibilityA two-sensor instrument that measures the vertical gradient of the geomagnetic field. By differencing two sensors separated vertically by 0.5-1 m, it cancels u...