Metal Detector Terms Part I - metal detecting terms

Metal Detecting Terms

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Metal Detector Air Test: A test performed by moving various sized metal samples beneath the metal detector searchcoil to check the detector’s features and target response. This test is not an accurate indicator of ground depth penetration capability.

Alkaline: A type of battery able to sustain longer periods of current drain with greater storage life when compared to the standard carbon-zinc type.

All Metal: Any operating mode or control setting which allows total acceptance of any type of metal targets. Usually associated with the Ground Balance mode.

Audio ID: See Tone ID.

Audio Response: See Target Response.

Auto Tune: Circuitry which continuously retunes the detector’s threshold to the initial manually tuned audio level. The retuning rate following target rejection or drift can be preset or variable.

Back Reading: A false signal, when operating in the discriminate mode, caused by a rejected target coming within one inch of or contacting the searchcoil bottom.

Bench Test: An air test to determine at what approximate discriminate settings various metal samples are rejected or accepted. The test is conducted in a non- metallic area.

Black Sand: One of the most extreme components of nonconductive, negative ground minerals. Also called magnetite (Fe304) or magnetic iron oxide.

Body Mount: A configuration whereby the control housing is separated from the control shaft and fastened to the operator’s body lessening arm fatigue and expanding usability for shallow water hunting. Also known as hip mount.

Cache: Any intentionally buried or secret hoard of valuables.

Carbon-Zinc: The most common standard dry cell battery type.

Coil: See Searchcoil.

Coin Depth Indicator: A visual indicator used in conjunction with calibrated circuitry to indicate depth of buried coins in inches or millimeters.

Concentric: A searchcoil configuration using one or more transmit and one receive windings having unequal diameters aligned on a common center; most recently arranged on the same plane and called coplanar concentric.

Conductive Salts: One of the major mineral types which make up the positive ground matrix. Wet, ocean-salt sand produces a positive rise or metallic type response on an air tuned threshold.

Conductivity: The measure of a metal target’s ability to allow eddy current generation on its surface.

Control Housing: A metal or plastic box which holds circuit boards, indicators, meter, controls and power supply.

Convertible/Combination: A metal detector configuration allowing versatility in operator handling, i.e., hand held to body mount.

Coplanar: Any searchcoil configuration in which transmit and receive windings occupy the same level or plane.

Crystal Controlled Oscillator: A transmit oscillator employing a crystal to maintain stable output frequency.

Depth Penetration: The greatest measure of metal detector’sability to transmit an electromagnetic field into the soil matrix and produce a target signal.

Detection Pattern: The densest or strongest region of the searchcoil’s electromagnetic field where detection occurs. Its shape is balloon and changes in size directly proportional to target surface area.

Detuning: Adjusting the audio threshold into the null or less sensitivity tuning zone. Also a method of narrowing a target signal width manually for precise pinpointing. This is accomplished by retuning to audio threshold over the target response area.

DISC: See Discrimination.

Discrimination: Adjustable circuitry which ignores or nulls audio responses from a specific conductivity range allowing positive responses to be heard from metals higher in conductivity above the discriminate control setting. Designed primarily to eliminate audio response from trash metals. See also Motion Discriminator.

Double Blip: A signal characteristic common to elongated ferrous targets such as nails or coins lying close to the surface detected in the All Metal no-motion mode.

Double D or 2 D: See Wide Scan.

Drift: A loss of threshold tuning stability caused by temperature change, battery condition, ground mineral content or detector design.