Physical contrast
Definition
The difference in a measurable soil property (density, susceptibility, resistivity, permittivity) between a target and its surrounding host material. No contrast means no signal, regardless of instrument sensitivity.
Related terms
- Dielectric permittivity
- A soil's capacity to store and transmit electric field energy. Higher water content raises permittivity and slows the radar wave. The contrast...
- Electrical resistivity
- The resistance of a volume of soil to electrical current flow. Wet, clay-rich, or decomposing organic material has low resistivity. Dry sand...
- Magnetic susceptibility
- A measure of how strongly a material is magnetised by an external field. Topsoil heated by fire or biological activity has elevated...
- Multi-method survey
- The deployment of two or more independent geophysical methods over the same search area. Anomalies confirmed by multiple methods carry higher confidence...
- Signal-to-noise ratio (SNR)
- The ratio of anomaly amplitude to background variation. Pipes, cables, rocks, roots, and instrument drift all add noise. A target is detectable...
Explained in
- Geophysical Survey Principles in Forensic ContextsThe difference in a measurable soil property (density, susceptibility, resistivity, permittivity) between a target and its surrounding host material. No contra...