Minelab E-Trac Manuel d'instructions télécharger pdf (Page 16)

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A Simple Detecting ExerciseDetecting Basics

Sweeping the Coil

You will obtain the best performance

when the coil is swept close and parallel

to the ground at all times. This will increase

detection depth and improve the response to

small objects. Avoid excessive brushing of the

coil on the ground. Though the coil assembly

is rigid and durable, sudden jolts or bangs

can cause random signals and inaccurate

target IDs. Careful sweeping will ensure the

coil performs to an optimum level at all times.

Targets

Metal objects are referred to as targets.

Targets are comprised of ferrous and

nonferrous metals. Ferrous metals are those

containing iron; such as steel, nails and some

types of coins.

Nonferrous metals are those which are not

magnetic, such as gold, silver, copper, bronze

and aluminium.

You may wish to nd a range of both ferrous

and nonferrous targets.

Examples of common targets:

Desired high ferrous target – war relic

Undesired high ferrous target – iron nail

Desired nonferrous target – gold coin

Undesired nonferrous target – pull-tab

Practise sweeping the coil over the ground

in a side-to-side motion while slowly walking

forward at the end of each sweep. Slightly

overlap the previous sweep to ensure full

ground coverage. An average sweep speed is

four seconds from left to right to left.

Before attempting to recover real targets, it is

important to understand how to interpret the

audio and visual signals of the detector.

Gather a collection of dierent metal objects,

e.g. various coins, gold and silver jewellery, a

nail, pull-tab, brass button and aluminium foil.

Take the detector outdoors, away from known

sources of EMI and metal objects.

Lay objects in a line, suciently spaced apart

to allow the coil to pass between them, as

shown below.

Detector Sounds

Turn the detector On.

The constant background ‘hum’ produced

by the detector is called the Threshold (pp.

58–9). Variations in the Threshold allow you

to hear very small and deep targets. It is also

used to help distinguish between desired and

undesired targets.

The detector may also produce False Signals

(Noise) when not over the ground or with the

coil held motionless. These may not be target

signals, but surrounding electromagnetic

interference (EMI). You can minimise these

False Signals by performing a Noise Cancel

(p. 31), or by reducing the Sensitivity (pp.

54–6) of the detector. It is generally better to

try to reduce False Signals by adjusting Noise

Cancel before resorting to reducing

the Sensitivity.

Sweep the coil across the targets one at

a time. Observe the LCD and listen to the

sounds of the detector as it passes over

each object. Although the LCD will give you

detailed information about the target ID, it is

important to pay attention to the dierence

in audio response between each of

the objects.

Note: If you are getting signals from a

visibly clear patch of ground, there could be

buried metal objects. Try nding another

area to practise.

CAUTION: Incorrect coil sweeping can

generate false signals or miss targets.

Nail Pull-Tab Foil Coins Jewellery

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