White Spectra VX3 Manual de Instruções descarregar pdf (Página 18)

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Spectra VX

User’s Guide

composite VDI that can land anywhere between pure ferrite

(VDI = -95) and pure salt. Other areas, like fertilized fields with

residual salt ions, can also have a composite ground response.

Many deserts have a layer of surface salts that have been

leached from the soil; this is generally not a problem as long as

it is dry.

Frequency

Metal detectors are produced using a wide range of trans-

mitted frequencies, from 1kHz up to around 100kHz, though

the vast majority fall in the VLF range of 3kHz - 30kHz. Low

frequencies usually favor thicker targets and metals of higher

conductivity, while high frequencies favor thin and low-con-

ductive targets.

Low frequencies also do a better job penetrating ground

mineralization, including salt. High frequencies tend to gener-

ate stronger ground and salt signals which can limit the ability

to distinguish weak targets. Obviously, when trying to detect

thin low-conductive targets (like nuggets and jewelry) in harsh

ground (like wet salt sand or black sand) there are competing

frequency requirements, so a compromise is necessary. With the

ability to run 3 simultaneous frequencies or any one of them

individually, VX

has the ability to deal with a wide variety of

conditions.

Interesting Experiment: Thickness matters because of a

phenomenon known as skin effect. To demonstrate this,

cut several identical flat squares (say, 1”x1”) of aluminum

foil. Test the VDI response of a single square, and see how

the VDI varies as you stack more squares (tightly)

together.

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White Spectra VX3 Manual de Instruções Página 18