KNOWLEDGE BASE ARTICLE
Metal Detecting Terminology
Terminology Index
Terminology Index

ACCU-TRAK��������������������������������������������������������� 2
Alkaline Battery������������������������������������������������ 2
All metal�������������������������������������������������������������� 2
Amplifier�������������������������������������������������������������� 2
Analogue ������������������������������������������������������������ 2
Auto tune������������������������������������������������������������ 2
Broad Band Spectrum (BBS)������������������������� 2
Coin, jewellery & relic hunting�������������������� 2
Concentric coil�������������������������������������������������� 3
Conductivity������������������������������������������������������ 3
CO�������������������������������������������������������������������������� 3
Continuous wave �������������������������������������������� 3
Control box��������������������������������������������������������� 3
Current����������������������������������������������������������������� 3
Depth������������������������������������������������������������������� 3
Digital������������������������������������������������������������������� 3
Discrimination��������������������������������������������������� 4
Discrimination pattern����������������������������������� 4
Detectorist���������������������������������������������������������� 4
Double-D coil (DD)������������������������������������������ 4
Dual Voltage Technology (DVT)������������������ 5
Eddy currents���������������������������������������������������� 5
Environmental noise��������������������������������������� 5
Electromagnetic field������������������������������������� 5
Falsing������������������������������������������������������������������ 5
Ferrous (Fe)��������������������������������������������������������� 5
FE��������������������������������������������������������������������������� 6
Frequency����������������������������������������������������������� 6
Frequency domain������������������������������������������ 7
Full Band Spectrum (FBS)������������������������������ 7
Gold prospecting��������������������������������������������� 8
Ground balance������������������������������������������������ 8
Ground mineralisation����������������������������������� 8
Ground noise����������������������������������������������������� 8
Ground tracking����������������������������������������������� 8
Halo effect���������������������������������������������������������� 8
Harmonic frequencies (harmonics)����������� 9
Hot rocks������������������������������������������������������������� 9
Iron Mask������������������������������������������������������������� 9

KNOWLEDGE BASE ARTICLE | KBA 04-1

Junk������������������������������������������������������������������������9
Lithium-ion battery (Li-ion battery)����������10
Monoloop coil��������������������������������������������������10
Multi-frequency�����������������������������������������������10
Multi Period Sensing (MPS)��������������������������10
Nickel cadmium battery (NiCd)������������������10
Nickel metal hydride battery (NiMH)�������11
Noise Cancel������������������������������������������������������11
Non-ferrous�������������������������������������������������������11
Notch Filter Discrimination��������������������������11Ohm���������������������������������������������������������������������11
Period�������������������������������������������������������������������11
Pinpointing��������������������������������������������������������11
Pulse Induction (PI)�����������������������������������������11
QuickMask����������������������������������������������������������12
Receive (Rx)�������������������������������������������������������12
Resistance����������������������������������������������������������12
Sealed lead acid battery (SLA)��������������������12
Search Coil (loop)��������������������������������������������12
Sensitivity�����������������������������������������������������������12
SETA����������������������������������������������������������������������12
Signal�������������������������������������������������������������������13
Sine wave�����������������������������������������������������������13
Smartfind Discrimination�����������������������������13
Square Wave������������������������������������������������������14
Target�������������������������������������������������������������������14
Target ID number��������������������������������������������14
Threshold�����������������������������������������������������������15
Time constant���������������������������������������������������15
Time domain�����������������������������������������������������16
Timings����������������������������������������������������������������16
Tone identification������������������������������������������16
Transmit (Tx) �����������������������������������������������������16
Trashy ground���������������������������������������������������16
Universal Serial Bus (USB) port�������������������17
VFLEX�������������������������������������������������������������������17
VLF (Very low frequency)�����������������������������17
Voltage����������������������������������������������������������������17

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Metal Detecting Terminology

ACCU-TRAK

ACCU-TRAK is the ground tracking technology used in the Eureka Gold metal detector.

Alkaline Battery

Alkaline batteries are non-rechargeable batteries. They are available in common battery sizes such as AA,
C & D and have a voltage of 1.5 volts per cell. These are the most commonly available battery.

All metal

All metal refers to operating a metal detector without any metals being masked or discriminated. All
metals will be detected regardless of ferrous or conductive properties.

AmplifierAn Amplifier is a device or electronic circuit that increases amplitude (strength) of an electrical signal. The
signal can be either an audio signal (sound) or a radio signal (electromagnetic).

Analogue

Analogue refers to a method of transmitting and receiving data between electronic devices or within anelectronic circuit. Analogue signals contain information in their amplitude (i.e. 2.83 volts) at a point intime or over a period of time. (Also see “Digital” on page 3)
1.5

Analogue signal (sine wave)

Amplitude

1
0.5
0
-0.5
-1

Time
-1.5

Auto tune

Auto tune is a metal detector feature that shifts the detector’s operating channel to reduce the effectof environmental noise. If an environmental noise source is operating at, or producing, harmonicfrequencies that match the detector’s operating channel the detector becomes susceptible to falsing.
By shifting the detector’s operating channel up or down the detector can avoid being affected byenvironmental noise. (Also see “Noise Cancel” on page 11)

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 has the benefit of superior depth, sensitivity to small targets
and accurate discrimination. BBS technology can be found in Minelab’s Sovereign GT and Excalibur II
metal detectors. (Also see “Full Band Spectrum (FBS)” on page 7)

Coin, jewellery & relic hunting

Coin, jewellery & relic hunting involves detecting for coins, jewellery & relics as opposed to gold
prospecting. Coin, jewellery & relic hunting metal detectors have different performance characteristics togold prospecting detectors. Coin, jewellery & relic hunting detectors have good discrimination and canbe programmed to reject specific types of metal objects or junk. They also generally come with a display
pod, so a user can determine what a target might be before digging.
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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 the target. Concentric coils tend to be noisier in highly
mineralised ground and require more overlap of sweep for thorough ground coverage.

Concentric coil

Inner winding (receive)

Outer winding (transmit)

Conductivity

Conductivity refers to how well a target allows electrical current to flow through it. In other words ahighly conductive target has low electrical resistance and therefore allows current to flow more easily.
Conversely a target with low conductivity has high electrical resistance and does not allow current toflow easily. (Also see ”Time constant” on page 15)CO

CO is an abbreviation that refers to conductivity on the Smartfind display found on the Explorer SE andE-TRAC.

Continuous wave

Continuous wave is a type of metal detecting technology. Continuous wave metal detectors create anelectromagnetic field that is applied to the ground in a continuous sine wave.

Control box

The control box encloses the electronic circuitry of the detector,
that generates the Tx (transmit) signals sent by the search coil andprocesses the Rx (receive) signals detected by the search coil.

Control box

Current

Current is the flow of electrical charge and is measured in Amperes(A or Amps). Current measurements are common on batteries andpower supplies (i.e. AA NiMH battery: 2600 mAh, DC power supply:
1.5 A). Current is also induced into targets by the electromagnetic
field produced by metal detectors, these are called eddy currents.
(Also see “Voltage” on page 17)

Depth

Depth in metal detecting terms refers to how deep a target isburied. A metal detector that can achieve greater depth is able to detect deep targets. Minelab’s E-TRAC,
X-TERRA and Explorer SE also have graphical depth indicators.

DigitalDigital refers to a method of transmitting and receiving data between electronic devises or within anelectronic circuit. Digital signals (or data) use only two states, high or low and generally conform to a
counting method called binary. Electronic circuits that process digital signals have many advantages
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Metal Detecting Terminology
over analogue circuits, including; less susceptible to noise and interference, able to process more
information, able to filter signals using less electronic components, are lighter and cheaper.

Amplitude

Digital signal representing the number 69

0

1

2

3

4

5

6

7

Time (clock cycles)

Discrimination

Discrimination is a metal detector function that recognises the differences between various typesof targets. Minelab has three different discrimination technologies; Variable discrimination, Notch
filter discrimination and the most advanced, Smartfind discrimination. Smartfind discrimination can
discriminate a target based on both Ferrous and Conductive properties simultaneously.
Ferrous properties refer to how much iron is in a target and therefore how strongly it’s attracted to amagnet. Ferrous targets tend to be trash, so can be discriminated/masked out based on their ferrous
properties alone by the detector. Conductive properties refer to how well a target conducts electricalcurrent and therefore responds to a metal detector’s electromagnetic field. Trash like nails and foil havedifferent conductive properties to valuable targets like coins and rings. In this case the metal detector
can make a judgement as to whether the target is trash based on conductivity.

Discrimination pattern

A Discrimination pattern is a graphical representation of accepted and rejected targets based on ferrous
and conductive properties. Targets with properties that appear in the shaded section are masked andtargets with properties that appear in the non-shaded area are accepted. Discrimination patterns
are used on Minelab’s X-TERRA series (one dimensional) as well as Explorer and E-TRAC with the twodimensional Smartfind discrimination display. (Also see “Discrimination” on page 4)

Detectorist

A detectorist is a person who regularly uses metal detectors professionally or as a hobby.

Double-D coil (DD)A double-D coil has two overlapping wire windings in the shape of two D’s (one reversed). The
characteristics of a Double-D coil are stability (especially in heavily mineralised ground), good depth andsensitivity, and a very thorough search pattern.

Double-D coil

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Metal Detecting Terminology

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.

DVT transmit signal

Voltage

0
-5
-10
-15

Voltage level 1

Voltage level 2

-20

Time

Eddy currents

Eddy currents are tiny electrical currents that are induced into targets when a metal detector’s
electromagnetic field is present. These eddy currents then generate an electromagnetic field around thetarget which can be detected by a metal detector.

1. Detector transmits anelectromagnetic field

2. Eddy currents are
induced into the target

3. Eddy currents generate
an electromagnetic field

Environmental noise

Environmental noise comes from power lines, underground cables, radar, other detectors or climaticconditions like thunder storms that produce electrical signals or noise that can interfere with a metal
detector’s operation.

Electromagnetic field

An electromagnetic field is a magnetic field that has been generated electrically. Metal detectors radiate
an electromagnetic field from the search coil. This influences buried targets, which then affects the signal
received back by the detector.

Falsing

Falsing occurs when a metal detector gives a detection response to electrical noise, ground noise or
bumping.

Ferrous (Fe)

Ferrous objects/targets contain iron and therefore are attracted to a magnet.
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Metal Detecting Terminology

FE

FE is an abbreviation that refers to a target’s ferrous properties on the Smartfind display found on the
Explorer SE Pro and E-TRAC.

Frequency

Frequency is the number of times a signal or wave completes a full cycle per second and is measured inhertz (Hz). Frequency is also the inverse of the wave’s period (i.e. frequency = 1/period)

Amplitude

One complete cycleTime
For example if a signal repeats itself 10 times every second the signal’s frequency is 10 Hz.

Amplitude

10 complete cycles in one second = 10 HzTime

The frequency that a metal detector operates at (transmitted by the search coil) affects its performance,
as a rule of thumb, the lower the frequency, the deeper it can penetrate the ground. At low frequencies
however, sensitivity to small low conductive targets is reduced. The higher the frequency, the higher thesensitivity to small targets, but will not penetrate as deeply.
In general, gold detectors operate at higher frequencies (to find small nuggets), while coin and treasuredetectors work at lower frequencies for deeper penetration. The exception to this is MPS type metal
detectors that are sensitive and deep seeking simultaneously.

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Metal Detecting Terminology

Frequency domain

Frequency domain refers to the viewing or analysis of signals with reference to frequency, rather thantime. (Also see “Time domain” on page 16)

1 kHz signal in the time domain

1.5

Amplitude

1
0.5
0
0.25

0.5

0.75

1

1.25

1.5

1.75

2

-0.5
-1

Time (milliseconds)-1.5

1 kHz signal in the frequency domain

1.2

Amplitude

1
0.8
0.6
0.4
0.2
0
900

950

1000

Frequency (Hz)

1050

1100

Full Band Spectrum (FBS)

FBS is Minelab’s patented multiple frequency metal detection technology. FBS transmits a broad range of
28 frequencies from 1.5 kHz to 100 kHz. This has the benefit of superior depth, sensitivity to small targets
and accurate discrimination. FBS technology can be found in Minelab’s E-TRAC, Explorer SE Pro and Safari
metal detectors. (Also see “Broad Band Spectrum (BBS)” on page 2)

Single frequency

KNOWLEDGE BASE ARTICLE | KBA 04-1

Three frequencies

FBS 28 frequencies

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Metal Detecting Terminology

Gold prospecting

Gold prospecting is the activity of searching for new gold. Gold prospecting metal detectors havedifferent performance characteristics to Coin, jewellery & relic hunting metal detectors. Gold prospecting
metal detectors have superior ground balancing abilities to operate in highly mineralised ground andcan detect targets at greater depth.

Ground balance

Ground balance is the ability of a metal detector to compensate for the effects of ground mineralisation.
Metal detectors see mineralised ground as one huge target, which makes detecting buried targets inmineralised ground difficult. Ground balance is an important feature, because ground mineralisation
impedes detection depth. The better a metal detector can ground balance, the deeper it will detecttargets in mineralised ground.

Ground mineralisation

Ground mineralisation refers to how magnetic the ground is. This doesn’t mean that mineralised groundproduces a magnetic field, but it does mean that particles or grains in the soil will be attracted to amagnet. Metal detectors see mineralised ground as one huge target, which makes detecting buried
targets in mineralised ground difficult. Minelab invented true automatic ground balancing technology in1987 to successfully counteract the effect of ground mineralisation.

Ground noise

Ground noise is the false signalling caused by a metal detector that is not ground balanced to the soil.
The ground noise occurs when the unbalanced detector’s search coil is swept across ground that varies
in mineralisation, soil type, rocks or has dips and holes.

Hole

Hot rock

Ground noise

Ground tracking

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

Halo effectHalo effect occurs after a target has remained undisturbed in the ground for a considerable amount oftime. As the target breaks down or rusts the soil immediately around it becomes highly mineralised. A
detector will see this area of high mineralisation and give a detection response indicating that the target
is larger than it really is.
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Harmonic frequencies (harmonics)

Harmonic frequencies are components of a signal or wave that are multiples of the fundamental
frequency. For example a 15 kHz signal will have harmonic frequencies at 30 kHz, 45 kHz, 60 kHz, 75 kHz
and so on. These harmonic frequencies reduce in magnitude as they get further and further away fromthe fundamental frequency of 15 kHz. Harmonic frequencies are best viewed in the frequency domain.

Amplitude

Fundamental
frequency

Frequency (kHz)Hot rocks

Hot rocks are rocks that are mineralised differently to their surrounding ground. For example a highly
mineralised rock buried in mildly mineralised ground would be considered to be a hot rock. However,a highly mineralised rock in an equally highly mineralised ground would not be considered to be a hot
rock. (Also see Ground mineralisation)
Mildly mineralised rock in mildly Highly mineralised rock in mildly Highly mineralised rock inmineralised groundmineralised groundhighly mineralised ground

Rock is not considered to be hot Rock is considered to be hot

Rock is not considered to be hot

Iron Mask

Iron mask refers to operating a metal detector with iron masked or discriminated. Only non-ferrous
metals containing little or no iron will be detected.

Junk

Junk (or trash) refers to unwanted ferrous or non-ferrous metal targets. Nails, paperclips and wire areexamples of ferrous junk and bottle tops, ring pulls and foil are examples of non-ferrous junk. Junk isoften buried amongst valuable targets like coins. To solve this, Minelab has a range of metal detectors
with the ability to ‘discriminate’ whether a target is likely to be treasure or trash based on both ferrous
and conductive properties.

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Metal Detecting Terminology

Lithium-ion battery (Li-ion battery)

Lithium-ion batteries are a new type of rechargeable battery that has advantages over older
rechargeable battery technologies like nickel-metal hydride (NiMH), nickel cadmium (NiCd) and sealed
lead acid (SLA). Lithium-ion batteries are lighter, have no memory effect and a low self discharge rate.

Monoloop coil

Monoloop coils are a special style of coil for MPS technology detectors (SD & GPX Series). These coils have
one winding of wire around the circumference of the coil, which is used to both transmit and receive.
The signal pattern of the Monoloop coil is cone shaped, requiring more overlapping. In extremely heavily
mineralised grounds they can be more difficult to ground balance, however they tend to provide slightly
better depth than the Double D coils.

Monoloop coil

Multi-frequency

Multi-frequency is a type of metal detector technology that uses more than one frequency. Single
frequency metal detectors can be limited due to their fixed frequency. This is because lower frequencies
detect deeper into the ground, but higher frequencies detect smaller targets. By combining multiple
frequencies into one detector, depth and sensitivity to small targets is achieved. (Also see“Broad Band
Spectrum (BBS)” on page 2 & “Full Band Spectrum (FBS)” on page 7)

Multi Period Sensing (MPS)Multi period sensing is Minelab’s patented pulse induction technology first released in Minelab’s SD2000
detector in 1995. Standard pulse induction metal detectors are limited due to their single pulse width.
MPS uses varying pulse widths that extract more information from targets, achieve better groundbalance, remove ground noise and detect to greater depths. (Also see “Dual Voltage Technology (DVT)”
on page 5)

MPS transmit signal
Voltage

0-5Long periods-10

Short periods
Time

Nickel cadmium battery (NiCd)

Nickel cadmium batteries are rechargeable batteries. They are available in common battery sizes such
as AA, C, and D, however at 1.2 volts they have a slightly lower cell voltage than alkaline and carbon zincbatteries. NiCds have high discharge current capabilities due to their low internal resistance, but sufferfrom memory effect and have a relatively high self discharge rate (will discharge themselves over about
ten weeks).
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Metal Detecting Terminology

Nickel metal hydride battery (NiMH)

Nickel metal hydride batteries are rechargeable batteries, which have advantages over NiCd batteries.
NiMH provide 1.2 volts per cell, but do not suffer from a memory effect and are capable of higher energy
densities than NiCd batteries.

Noise Cancel

Noise cancel is a metal detector feature that automatically shifts the detector’s operating frequency orfrequencies to reduce the effect of environmental noise. If an environmental noise source is operating ator producing harmonic frequencies that match one or more of a detector’s frequencies then the detector
becomes susceptible to falsing. By shifting the detector’s frequency up or down the detector can avoid
being affected by environmental noise. (Also see “Auto tune” on page 2)

Non-ferrous

Non-ferrous materials do not contain iron and are not attracted to a magnet. (Also see Ferrous)

Notch Filter Discrimination

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

Ohm

Ohm is a unit of measure of electrical resistance (symbol Ω). Resistance measurements are common on
headphones and speakers. (Also see “Voltage” on page 17 & “Current” on page 3)

PeriodAmplitude

PeriodTime
Period is the time it takes for a wave or signal to complete one
cycle. The period is also the inverse of the wave’s frequency. (i.e.
period = 1/frequency)

Pinpointing

Pinpointing is the activity of narrowing down the location of aburied target. Many of Minelab’s detectors have a pinpointing
mode that allows the user to determine the exact location of atarget before digging. The process involves putting the detector
into pinpoint mode and slowly sweeping the ground above
the target to find the strongest response, then turning 90º andsweeping again to get an accurate target location.
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Metal Detecting Terminology

Pulse Induction (PI)

Pulse Induction (PI) is a type of metal detecting technology. Pulse induction operates by sending
short pulses of voltage to the metal detectors coil. These short pulses cause a magnetic field to begenerated which quickly dissipates at the end of each pulse. Any metal targets that induce the magnetic
field remain magnetised for a short time after the end of a pulse. The target’s decaying magnetism isthen detected by the detector’s coil. (Also see “Multi Period Sensing (MPS)” on page 10 & “Dual Voltage
Technology (DVT)” on page 5)

QuickMask

QuickMask is a feature available on Minelab’s E-TRAC. Quickmask allows a user to quickly edit andcustomise a discrimination pattern.

Receive (Rx)

Receive is the process of collecting a signal or magnetic field by the metal detector’s search coil.

ResistanceResistance is the opposition to current flowing in an electrical conductor and is measured in Ohms (Ω).

Sealed lead acid battery (SLA)

Sealed lead acid batteries are rechargeable batteries. They come in a wide variety of sizes and are mostoften packaged in 6 volt or 12 volt packs. SLA batteries have high discharge current capabilities due totheir low internal resistance.

Search Coil (loop)

The search coil is the circular or elliptical plate that is swept above theground during detecting. It transmits electromagnetic signals into
the ground and receives the response. The word coil actually refers to
the wire windings inside the housing, which can take different forms
and shapes. For more information on the different types of coils see
Concentric coil, Double-D coil and Monoloop coil.

Sensitivity

Search coil

Sensitivity refers to how responsive a metal detector is to small or deeptargets.

SETA

SETA is an acronym for Smart Electronic Timing Alignment. SETA technology enables a detector withmultiple timings to individually and automatically align each channel in a way that is not possible
with manual adjustments. This results in reduced noise and interference, improving sensitivity, groundbalancing and detection depth across all timings.

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Metal Detecting Terminology

SignalSignal in metal detecting terms refers to both the transmitted magnetic field from the detectors searchcoil and the received magnetic field from a metal target.

Sine wave

A sine wave or sinusoid is the name of a waveform that mathematically corresponds to the sine function[y(t) = A•sin(ωt + θ)]. A pure electrical sine wave does not produce harmonic frequencies.

Amplitude

Sine wave

Time

Smartfind Discrimination

Smartfind is Minelab’s unique two dimensional scale of discrimination. Smartfind graphically represents atarget’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 tobottom. 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.

E-TRAC Smartfind display
Two dimensional Smartfind
Discrimination Pattern

Discrimination Pattern (Accepted)
The white (clear) area of the Disc.
Pattern indicates the target FE-CO
numbers that are accepted
Discrimination Pattern (Rejected)
The black area of the Disc. Patternindicates the target FE-CO numbersthat are rejected

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 toKNOWLEDGE BASE ARTICLE | KBA 04-1

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Metal Detecting Terminology
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.

Explorer Smartfind display
Two dimensional Smartfind
Discrimination Pattern

Discrimination Pattern (Accepted)
The white (clear) area of the Disc.
Pattern indicates the target FE-CO
numbers that are accepted
Discrimination Pattern (Rejected)
The black area of the Disc. Patternindicates the target FE-CO numbersthat are rejected

Square Wave

A square wave is the name given to a waveform that has rapid transitions from one state to another.
Square waves are used in electronics as clock signals, timing pulses and control signals. Square waves
generate many harmonic frequencies.

Square wave

Amplitude

1.5

1

0.5

0

Time

TargetTarget refers to any buried metal object that can be detected by a metal detector. A target can be either
valuable coins or junk like bottle tops. The term does not refer to the value of the buried object.

Target ID number

Target ID numbers are numbers that identify targets based on ferrous and/or conductive properties. The
table below shows some typical target IDs from an X-TERRA 305.

TargetUS Quarter
Australian $1 coin
Ring pull
Wedding ringLong screw
Short screw
Paper clip

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Target ID
44
32
12
8
-4
-4
-4

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Metal Detecting Terminology

ThresholdThreshold 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.
When the Threshold is toohigh a faint signal is masked
and only the peak of theloud signal is audible
above the Threshold.

Threshold level
Audio Range thatyou are able to hear

FaintsignalmaskedLoud signal
just audible

FaintsignalVery
loudsignalFaint signal
now inaudible

Loud signal
audibleWith the Threshold set
correctly both target signals
are easily heard.
Audio Range thatyou are able to hear
Threshold level
Faint signal
now inaudible

Loud signal
audibleA Threshold level that is too
low does not allow faint target
signals to be heard.
Audio Range thatyou are able to hear

FaintsignalmaskedLoud signal
just audible

Threshold level

Time constantTime constant is a measure of a target’s combined conductivity and inductance. A target with highconductivity (low resistance) and high inductance will have a long time constant (i.e. gold ingot). A
target with low conductivity (high resistance) and low inductance will have a short time constant (i.e. finejewellery). Minelab metal detectors are capable of detecting the full range of time constants.

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Metal Detecting Terminology

Time domain

Time domain refers to the viewing or analysis of signals with reference to time, rather than frequency.
(Also see “Frequency domain” on page 7)

1 kHz signal in the time domain

1.5

Amplitude

1
0.5
0
0.25

0.5

0.75

1

1.25

1.5

1.75

2

-0.5
-1

Time (milliseconds)-1.5

1 kHz signal in the frequency domain

1.2

Amplitude

1
0.8
0.6
0.4
0.2
0
900

950

1000

Frequency (Hz)

1050

1100

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 ofdifferent timings in the GPX series of detectors that achieve optimum depth, sensitivity and groundbalancing across different detecting conditions. (Also see “Multi Period Sensing (MPS)” on page 10, “DualVoltage Technology (DVT)” on page 5 & “SETA” on page 12)

Tone identification

Tone identification is similar to target ID numbers; however, instead of using displayed numbers different
tones are associated to different target IDs.

Transmit (Tx)

Transmit is the process of sending a signal or magnetic field from the metal detector’s search coil.

Trashy groundTrashy ground is ground that has high levels of junk.
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Metal Detecting Terminology

Universal Serial Bus (USB) port

A Universal Serial Bus is a type of computer data port. Minelab’s E-TRAC has a USB port that enables it tocommunicate with a PC to upload and download settings and discrimination patterns.

VFLEX

VFLEX is Minelab’s metal detecting technology used in the X-TERRA range of detectors. VFLEX uses stateof the art digital electronics to enhance standard single frequency detection technology. This has theadvantage of providing dependable performance and improved immunity to outside interference. VFLEX
technology also has an added advantage that changing the detector’s coil also automatically changes
the detector’s operating frequency. This means that an X-TERRA detector can operate at different
frequencies allowing the detector to be easily modified to suit different detecting conditions.

VLF (Very low frequency)

VLF is a type of metal detecting technology. VLF metal detectors create an electromagnetic field that is
applied to the ground in a continuous sine wave.

Voltage

Voltage is electrical potential and is measured in volts (symbol v). Voltage measurements are common
on batteries and power supplies (i.e. AA NiMH battery: 1.2 v, DC power supply: 12v). Voltage is used
to energise a metal detector’s search coil, which in turn generates the electromagnetic field. (See also
“Current” on page 3 & “Resistance” on page 12)

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