Reference
Metal Detecting Glossary
Plain-English definitions of the terms you'll see in manuals, reviews, and forum threads.
- Concentric Coil
- A coil with two coaxial loops. Tends to give crisp target ID in clean ground and a cone-shaped detection field.
- DD Coil
- A coil with two overlapping D-shaped loops. Provides a wider, blade-shaped detection field with better depth and separation in iron-heavy ground.
- Discrimination
- A detector setting that tells the machine to ignore certain target ID ranges — typically iron and foil — so you don't dig the most common trash.
- Ground Balance
- A detector adjustment that cancels out the response of the ground itself, allowing the machine to detect targets cleanly in mineralized soil.
- Hot Rock
- A rock with enough mineral content (often iron oxide) to trigger a detector signal as if it were a metal target. Common in gold country.
- Iron Audio
- A feature that lets the detector tell you about iron targets through audio (often a low tone) instead of hiding them entirely with discrimination.
- Multi-Frequency
- A detector that transmits multiple frequencies simultaneously, then combines results to cancel ground response and improve target identification — particularly useful at saltwater beaches.
- Notch
- A discrimination setting that ignores a narrow target ID range — for example, foil — while still detecting targets immediately above and below it.
- PI — Pulse Induction
- A detector technology that sends short pulses and listens for echoes. Largely ignores ground mineralization (great in saltwater and on hot rocks) but produces weak target ID and discrimination.
- Pinpointer
- A handheld secondary detector used after the main detector has located a target area, to pinpoint the exact spot in the hole or displaced dirt.
- Plug
- The flap of sod or turf you cut to recover a target. A clean plug, replaced and stamped down, leaves the ground undisturbed once the grass re-knits.
- Recovery Speed
- How quickly a detector resets between targets. Higher recovery speeds help separate two close targets but can cost a little depth.
- Target ID
- A numeric or visual indicator of a buried target's likely identity, based on its conductivity. Higher conductivity (silver, copper) returns higher numbers; lower conductivity (iron, foil) returns lower numbers.
- Threshold
- A constant low audio tone that signals the detector is operating normally. A break in the threshold can indicate a faint target — particularly useful in gold prospecting.
- VLF — Very Low Frequency
- A detector technology that sends a continuous transmitted signal and measures the phase shift of the return signal to identify targets. Provides target ID and discrimination.