Auto Tune
Auto tune is a detector function that moves the detector’s operating channel away from a source of interference, reducing the effect of Environmental Noise coming from an unknown source. If this interference source is operating at a similar frequency to, or producing harmonic frequencies that match the detector’s operating channel, then the detector will become susceptible to falsing and spurious random signals. By moving the detector’s operating channel away, either up or down then the detector is able to run more quietly, and signals that could be hidden in the chatter are able to be heard.

Another tuning function is the manual tuning button or knob found on the GP and GPX series of detectors which allows the operator to select a frequency within the limits of the control to gain a benefit of the size of targets he is wanting to locate. Lower frequencies are known to be better for larger deeper nuggets, and higher frequencies are suited to smaller nuggets.

Conductivity
Conductivity refers to the ability of a target to allow electrical current to flow through it, specifically Eddy Currents for this application. A highly conductive target has low electrical resistance and allows current to flow more easily, whereas a target that is lowly conductive has a high electrical resistance and does not allow the current to flow easily. The conductivity of a target is linked to it's Time Constant.

Discrimination
Discrimination is a feature in a metal detector that gives the operator some ability to recognise the differences between various sorts of targets, specifically metal targets. The discrimination feature on Minelab detectors measure both ferrous properties and conductive properties to make a calculation. Ferrous refers to the amount of iron in a target and how strongly it is attracted to a magnet. Ferrous targets are generally regarded as rubbish, and can be discriminated or masked out based solely on this property. Conductivity, as above, is how well a target conducts electrical current and responds to a detector’s electromagnetic field. Rubbish like tin and nails have different conductive properties to more valuable targets like coins and gold. This allows the detector to make a judgement about the targets identity. Coin and Relic detectors are very good at this and their accuracy is excellent allowing the operator to know what the target is before even digging it.

Discrimination Pattern
Based on the above a target is able to accurately be assigned with a numerical representation (one dimensional) of its properties. For the X-TERRA series, targets with properties that have been rejected appear in the shaded section and are masked (discriminated out) while targets with properties that fall in the clear area are accepted. These targets are able to be added and removed form the Discrimination Patterns as the operator desires. The Explorer and E-TRAC with the two dimensional Smartfind discrimination display assign two numbers to a target and place it in a grid according to those numbers. As many targets are made from several metals, this means that there is even more accurate identification available for a specific target.

Eddy Current
Eddy currents are tiny electrical currents that are induced into a target when the target is exposed to an electromagnetic field. As a result these eddy currents then generate an electromagnetic field around the target itself which can be detected by the receive circuit of a metal detector's coil. This magnetic field can be many thousands of times smaller than the one the coil generated, so the detector needs to be a very sensitive instrument to detect these small fields.

Environmental Noise
Environmental noise can come from power lines, 2 way radios, underground cables, some Gps, radar, other detectors or climatic conditions like thunder storms and solar flares that produce electrical signals/spikes or spurious noises that can interfere with a metal detector’s operation.

Electromagnetic Field
An electromagnetic field is a magnetic field that has been generated by using electricity. When current flows in a conductor, a field is generated around the conductor. Metal detectors emit an electromagnetic field from their search coil. This induces eddy currents in buried targets and the small electromagnetic fields as a result are then available to be detected by the coil.

Falsing
Falsing ( or false signals ) is when a metal detectors coil is bumped on the ground or an obstacle, the control box or coil cable is bumped abruptly, or it gives a response to electrical noise or ground noise.

Ferrous
Ferrous targets are those that contain some amount of iron in their elements and consequently will be attracted to a magnet.

Frequency
A detectors frequency refers to the number of full cycles that are completed in the searchcoil in a one second timeframe. This is indicated in hertz (Hz). Higher frequencies are more sensitive to smaller targets, while lower frequencies are more beneficial for larger targets as they penetrate more deeply.

Full Band Spectrum
FBS or Full Band Spectrum refers to Minelabs patented multiple frequency technology. FBS detectors transmit 28 different frequencies in the range from 1.5Hx to 100Hz, giving a broader ability to detect any target available and an accurate discrimination ability.

Ground Balance
Ground balance is a function of a metal detector that allows it to adjust and compensate for the mineralisation levels in the ground, hence making a metal target more easy to recognise. Ground mineralisation masks target signals so accurate ground balance is essential to allow the operator to recognise those smaller responses that may mean a successful trip. Ground balance can be split into manual balance where the operator is responsible for making every adjustment needed, and automatic balance where the detector has the ability to adjust itself as the ground mineralisation changes.

Ground Balance Speed
This term refers to automatic ground balance and more specifically the speed at which the detector adjust itself to the mineralisation changes in the ground. Later Minelab pulse induction detectors offer 3 sppeds, slow, medium and fast, of which medium is the normal preference. As it is directly related to the "hotness" or variability of the ground one of the other options may be utilised if warranted.

Ground Mineralisation
Mineralisation is how magnetic the ground is, and is often the amount of iron contained in the soil. As Gold and iron have an iffinity, many goldfields are rich in iron especially those in Australia. This iron may be present as Ironestone lumps or small black sand particles that are attracted to a magnet.

Ground Tracking
This is also referred to as Automatic Ground Balancing. It is the detectors ability to notice changes in the ground balance and adjust itself accordingly allowing the operator more detecting time due to not having to stop constantly and manually adjust the ground balance. It also ensures that the detectors maximum depth on a Target is available because it is accurately adjusted.

Halo Effect
Metal objects, especially iron objects, as they lay undisturbed can leach into the ground as they corrode away thereby presenting a bigger target area to the detectors coil. The detector sees this as a target larger than it actually is, and in the case of a shallow target the response when the soil is disturbed by digging can lessen to a large degree. There is great debate about whether Gold nuggets leach or not.

Hotrocks
This term is given to rocks that have mineralisation properties that are far greater than their surrounding soils. A highly mineralised rock will be a "hotrock" if situated in mildy mineralised soil, but will not be detected if situated in soil that is of equal mineralisation content.

Threshold
Threshold is the continuous audible level of sound emitted by the detector. The threshold can be set anywhere between silent and loud; but a soft audible level is normally suggested.

Timings
Timings refer to the digital switching rates that control the internal electronics of the detector. In the GPX series of detectors the timings generate a pulse train to create the transmit waveform. The same timings generate synchronised switching signals to control the receive electronics.
Selecting different timings and thus changing both the transmit waveform and synchronised receive switching signals have benefits for different ground types and targets. Minelab has created a range of different timings in the GPX series of detectors that achieve optimum depth, sensitivity and ground balancing across different detecting conditions. (Also see “Multi period sensing (MPS)”, “Dual Voltage Technology (DVT)” & “SETA”)