Metal Detecting Glossary

Air Test - Testing the depth capabilities of a metal detector in the air. It is usually done by waving metal targets in front of a coil. Air tests are not an accurate representation of the depth sensitivity of the detector, because ground conditions often decrease the detection depth in the field

All-Metal - A mode of the detector with zero discrimination level, allowing for search of all metallic targets. This mode should be used when prospecting, and sometimes to search for deeper targets

Audio identification - Ability of metal detectors to produce different audio signals for different metals

Autotrac, Automatic Ground Tracking - A feature of some metal detectors creating continuous adjustment of ground balance to current ground conditions

Automatic tuning - A feature creating continuous adjustment of audio threshold after target rejection and drift

Back reading - False signal caused by contact between trash items and the search coil

Black sand - Non-conductive negative ground mineralization

Cache - A collection of valuables, usually coins or jewelry

Co-axial coil - A searchcoil with two central receiving windings and one transmitting winding in between. All are identical in diameter

Concentric coil - A searchcoil with one receiving winding and one or more transmitting windings, unequal in diameter aligned on a common center

Conductivity - ability of metals and minerals to transmit electricity

Control Box - The main part of the metal detector containing the processing unit, power supply, and controls

Co-planar coil - A searchcoil in which receiving and transmitting windings are in the same plane

2D coil - A co-planar coil with two overlapping D-shaped windings

Discrimination - A feature of most metal detectors rejecting some metal targets, while allowing others to respond. Little discrimination dismisses iron targets, then gold and aluminum, then copper and silver. Setting discrimination too high will cause you to miss valuable targets. No discrimination is recommended for prospecting.

Detection pattern - The area of searchcoil penetration, where any targets in the area will be located. The area depends on the coil size, coil type, and the depth

Detuning - Lowering audio threshold for better pinpointing

Drift - Loss of threshold due to changes in mineralization of the ground, temperature, etc

Electromagnetic field - A magnetic field created through the conductive material by electric force

Elliptical coil - A searchcoil in the shape of an ellipse, usually used for prospecting

Faraday shielding - Special wrapping of the searchcoil to eliminate electrostatic interference

Ferrous - Metals made of or containing iron or steel

Ferrous oxide - oxide created by decomposing metal objects. Also contributes to mineralization of the ground

Frequency - Number of alternating current cycles produced by a metal detector. Measured in Hertz (Hz)

Ground balance - An adjustment of a metal detector to eliminate ground mineralization. Some metal detectors come with preset ground balance, while others have automatic or manual ground balance

Halo effect - refers to the condition when a metal object has been in the ground for a long time and accumulated oxide around itself. This makes the object appear much larger to the metal detector

Hot rock - A rock containing minerals, which creates a false signal by the metal detector

Interference - Causes of static, unwanted false signals, or other hindrance of performance in the environment. Interference is caused by telephone lines, underground power cables, radio towers, other detectors, or climatic conditions such as thunderstorms

Meter - A visual display, either a needle on a scale or a graph on the LCD, giving the metal detector user information about the target and metal detector state

Mineralized ground/soil - Soil containing conductive elements

Mixed mode - A combination mode combining all-metal and discriminate modes in one

Motion discriminator - An ability of metal detector to activate ground balance and discrimination upon motion of the searchcoil

Microprocessor - A limited computer inside the metal detector control box, responsible for most of the features a metal detector has

Negative ground - Soil containing magnetic minerals which has a negative effect on the threshold

Neutral ground - Soil containing no non-conducting or conductive properties

Non-ferrous - Refers to metals not containing iron, like silver, gold, platinum, copper, aluminum, lead, and zinc

Non-motion - A mode on some detectors allowing detection without the motion of the searchcoil

Notch discrimination - A mode allowing to reject targets within certain discrimination range. Used to accept most targets within the nickel range, but reject pull tabs

Oscillator - Used to power searchcoil transmitting windings by generating a rate of current frequency

Pinpointing - Locating the exact position of the target

PI - A type of metal detector usually used in salt water

Positive ground - Soil containing conductive minerals which has a positive effect on the threshold

Prospecting - Searching for gold nuggets

Rejection - Discrimination prevents signal from unacceptable targets

Relic - A treasure from the past.

Self adjusting threshold - A feature automatically adjusting audio threshold after a change in the conditions

Two box - A detector with transmitting and receiving windings separate. These detectors can find large targets deep in the ground, but ignore targets close to the surface

Search coil - Part of metal detector responsible for sensing targets. Coils create an electromagnetic field and sense the field created by the targets. Coils contain transmitting and receiving windings in various configurations

Sensitivity - Measure of the ability of metal detector to sense the electromagnetic field around a target. Detector's sensitivity measures its ability to find small targets. In normal conditions higher sensitivity also corresponds to greater depth

Signagraph - A graph representing a target's electric and magnetic properties

Silent search - A feature in some metal detectors to get rid of the audio threshold background noise.

Skid plate - Protective cover for the searchcoil

Stability - Ability of metal detector to perform without interference

Surface blanking - A feature rejecting targets close to the surface, but accepting the ones deeper

Target masking - Occurs when lots of trash targets cause good targets to be rejected

Ten turn control - Control used on prospecting detectors for precise ground balance

Threshold - Minimum audio signal, usually hum sound in the background. It occurs in the best combination of discrimination, sensitivity, and other controls. Any target disrupts the threshold and becomes audible to the user

Tone control - Control for adjusting audio frequency or pitch

Transmitting winding - Wire in the searchcoil sending electromagnetic field into the ground

TR (transmitter/receiver) - A type of metal detector, most popular in the past

VLF (Very Low Frequency) - Type of metal detectors, usually 3 to 30 kHz

VLF/DISC - Metal detectors capable of mineral free operation in both discriminate and all-metal modes

VLF/TR - Metal detectors which operate in both all-metal, ground balance mode and non-motion discriminate, non-ground balance mode

Wide scan coil - A searchcoil that detects targets across its entire diameter