Minelab Technologies

Continuous sine wave (VLF)
This is the traditional type of technology used in most basic metal detectors. These detectors are also known as VLF (very low frequency) models. While signal processing has improved enormously, the basic way that the signal is sent out and received back hasn't changed a lot. Continuous sine wave detectors create an electro-magnetic field, which is transmitted in to the ground in a continuous wave.

Broad Band Spectrum (BBS)
BBS is Minelab’s patented multiple frequency metal detection technology. BBS transmits a broad range of 17 frequencies from 1.5 kHz to 25.5 kHz. This broad range of frequencies gives the detector more information about a target and the surrounding environment. BBS technology can be found in Minelab’s Excalibur II and Sovereign GT metal detectors.

Multi Period Sensing (MPS)
Multi period sensing is Minelab’s patented pulse induction technology. Standard pulse induction metal detectors are limited because they use a single pulse width. MPS uses varying pulse widths that extract more information from targets, achieve better ground balance and detect to greater depths.

Dual Voltage Technology (DVT)
Minelab’s patented Dual Voltage technology (DVT) is implemented in the GPX series of metal detectors. DVT transmits two different voltage levels from the search coil. This has the advantage of improved ground balance, increased sensitivity to small targets and increased detection depth.

Automatic ground tracking
Ground tracking refers to the ability of the detector to track changes in ground mineralisation and automatically adjust the ground balance to suit. This ensures perfect ground balance and maximum detection depth, eliminating the need for the operator to stop and manually adjust the detector as ground conditions change.

Pre-set ground balance
Pre-set ground balance is preset to suit a particular soil type. This limits where the detector is able to be used, but will generally work well in less mineralised sites such as parks, playgrounds and dry beach sand.

Discrimination
Discrimination is the ability of the detector to identify the type of metal object detected and to eliminate the unwanted items and indicate only on the desirable ones.

Variable discrimination
This is the most basic of discrimination types. It works like a demarcation line in the conductivity level. This level can be set by the operator and all metals with conductivity lower than where the level is set are eliminated & all metals with a higher conductivity are accepted.

Notch filter discrimination
Notch filter discrimination is the ability of a metal detector to select which of the conductivity segments in the discrimination scale are active or disabled. If a segment is notched out then metals with that level of conductivity will be masked and will not produce a response.

Smartfind^(TM) discrimination
Smartfind is Minelab’s unique two dimensional scale of discrimination. Smartfind graphically represents a target’s ferrous and conductive properties on the same display.

Smartfind is a feature of two Minelab metal detectors; E-TRAC and Explorer SE Pro.

E-TRAC Smartfind:
The horizontal axis rates the target on its size/conductivity (CO), ranging 1–50 from left to right. The vertical axis rates the extent of the target’s ferrous characteristics (FE), ranging 1–35 from top to bottom. A FE value of 1 represents low ferrous characteristics and a value of 35 represents high ferrous characteristics. Similarly, a CO value of 1 represents low conductivity and 50 represents high conductivity.

Explorer SE Pro Smartfind:
The vertical axis rates the target on its size/conductivity (CO), ranging 0–31 from bottom to top. The horizontal axis rates the extent of the target’s ferrous characteristics (FE), ranging 0–31 from right to left. A FE value of 0 represents low ferrous characteristics and a value of 31 represents high ferrous characteristics. Similarly, a CO value of 0 represents low conductivity and 31 represents high conductivity.

Discrimination scale
A discrimination scale segments the range of metals by their conductivity, normally from low conductivity through to high conductivity. The range and number of segments in the scale can determine the accuracy and precision of target identification. The number of segments also determines the accuracy and precision of the Notch filter discrimination.

Tone identification
Some detectors will indicate the possible ID (identity) of a target, by changing the tone of the target signal. Generally low conductive metals will give a lower tone while highly conductive metals will give a higher pitched tone.

Search coils

Size
The size of a search coil can influence the detection depth or sensitivity of a metal detector. The larger the coil, the deeper it detects, but will have less sensitivity to small targets. Conversely the smaller the search coil’s diameter, the more sensitive it becomes but looses detection depth.

Smaller coils are lighter, easier to control and may be chosen for their ability to negotiate difficult terrain or undergrowth. They are also an advantage in areas of high trash.

Shape
The most common coil shapes are conventional solid round coils, elliptical shaped coils and the open web coils. The main reason for the change in shape is to conform to a physical requirement, i.e. an elliptical coil can be pushed around bushes or between rocks easier than a round coil and open web coils move through water easier and are lighter. Conventional round coils are often more stable and perform better and are particularly popular for gold prospecting.

Configuration
The three most common types of coil windings are Concentric, Double-D, and Monoloop. The difference between these coil types is the pattern the wire is wound within the search coil.

Concentric coil
A Concentric coil has an inner circle and an outer circle wire winding. Its search pattern is cone shaped and can be useful for accurately pinpointing a target. Concentric coils tend to be noisier in highly mineralised ground and require more over lap of sweep for thorough ground coverage.

Double-D coil
Double-D coils are the preferred coils for most detecting. They give a blade or chisel shaped signal that covers the ground more uniformly and once an operator becomes accustomed to the signal, pinpointing can be very accurate. Double-D coils are also preferred for their superior ground balancing ability.