Product Manual

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SECTION1: OPERATION
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Introduction
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TheGA‐72CdMagneticLocatordetectsthemagneticfieldofferromagneticobjects.Itresponds
tothedifferenceinthemagnetic field between twosenso rs thatarespacedapproximately14
inchesapart.Thisdifferenceisreferredtoasthe“signalstrength”throughoutthismanualand
isrepresentedintheinstrument
by anaudiotoneand visualindicationofbothsignalstrength
and polarity.While most objects can be located using either the audio or visual indication,
simultaneoususeofbothwillhelpyoupinpointatargetanddetermineitsorientation.
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Figure1illustratesanapplicationinwhichthelocatorisused
todetectanironmarkerusedfor
property line identification.As shown, the magnetic field of the iron marker is stronger at
SensorAthanitisatSensorB.Asaresult,thefrequencyoftheaudiosignalishigherthanthe
idlingfrequency,40 Hz,whichexists when
thefieldstrengthis thesameat bothsenso rs.This
stronger signal also causes the digital indication to peak in either the positive or the negative
directionwhentheaudiosignalisatitshighestfrequency.
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Figure1:DetectingMagneticFieldofanIronMarker
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When shipped, the locator is
set to provide an audio signal that is heard as long as the
instrumentisturnedon.Ifdesired,youcanchangethissettingtoanaudiosignalthatisheard
onlywhentheinstrumentiswithindetectionrangeofanobject(refertopage5ofthismanual
forinstructions).
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