Minelab Eureka Gold Manuel de service télécharger pdf (Page 9)

Page 14 The Minelab Eureka Gold

5.2 Threshold Control

The Threshold Control is used to set the continuous audio ‘hum’ or

‘threshold’ level. The Threshold Control should be set so the threshold

level is just audible, e.g. not too loud. Prolonged use at a loud level could

be irritating to the operator, and could mask a faint signal.

It is important to know that small targets or large but deep targets may not

produce a distinct audio signal, but rather cause only a slight deviation

from the threshold level. If the threshold level is set too high or too low, the

very small variations in audio signal which indicate very small or deep

targets can be missed (see figure 14).

Note: While detecting, the Threshold Control may require occasional

readjustment.

Therefore this control is a volume limiter. It is a useful feature when using

headphones, as audio signals which would otherwise be uncomfortably

loud can be limited while maintaining full response to small signals.

Figure 13 - Volume Control (The maximum audio output (volume) can be limited)

Figure 14 - Threshold Control Settings

Page 15 The Minelab Eureka Gold

In the graphs (on page 13) the dotted line represents the level at which the

audio output becomes audible; signals cannot be heard if they are below

that dotted line. When the threshold is set correctly it is just above being

audible and even small variations in the sound level will be heard. If the

threshold level is set too high, then small variations in audio signal might

not be discernible above the threshold level. If the threshold level is set too

low there is no audible background audio signal and small target signals

will not go above the threshold of audibility.

5.3 Sensitivity Control

The Sensitivity Control affects the strength of all signals, small shallow

targets, large deep targets, mineralisation and other interferences. The

Sensitivity Control also affects the level of sound produced by the detector

for a particular target. However, unlike the Volume Control, it affects both

small and large targets alike.

It is recommended that in most ground the Sensitivity Control should be

set to the maximum sensitivity. This is obtained by turning the control fully

clockwise.

Figure 15 – Sensitivity Control

(The audio output is amplified according to the Sensitivity setting)

The Sensitivity Control should be decreased only in case of electrical

interference or poor ground conditions such as heavy mineralisation or

heavy ironstone. The sensitivity should be decreased just enough to make

the detector usable.

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Minelab Eureka Gold Manuel de service Page 9