User Manual

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September1,2011 Page3of6
StrataProximitySurfacePADmodelHA‐S‐2200‐SUsersManualv1.0 2011
1 Overview
TheSurfacePADispartofacompleteHazardAvertproximitywarningsystemfromStrata
ProximitySystemswhichprovideswarningstobothindividualsandtovehiclesandmachinery
toalertthemthattheindividualwearingthePADhasenteredtooclosetoanoperatingpieceof
equipmentandisinadangerous
situationorthatvehiclesormachineryaregettingclose
enoughthatacollisionpossibilityexists.
1.1 TheoryofOperation
TheSurfacePADiswornbyanindividual.ThefunctionsoftheSurfacePADare:
 Todetectthepresenceofa73kHzelectromagneticfieldgeneratedbyvehiclesormachinery
equippedwiththeHazardAvertsystemandtodetermineifthefieldstrengthleveldetected
indicatesthattheindividualisinorisapproachingadangeroussituation.
 Toprovideanaudibleandvisualindicati on to
theweareroftheSurfacePADthattheyare
approachingorareinadangerouslocationasaresultofthe73kHzfieldstrengthlevel.
 Totransmita916.48MHzRFsignaltovehiclesormachineryequippedwiththeHazardAvert
systemsignalingthattheindividualisenteringorhas
enteredintoadangerousarearelativeto
thevehicleormachinery.
TheSurfacePADhasa73kHzreceiverthatisconstantlyonandmonitoringthestrengthof
fieldsemittedbyvehiclesandmachineryequippedwiththeHazardAvertproximityandcollision
avoidancesystem.TheSurfacePADmonitorsthestrengthofthe73kHzfieldsinthreeaxesand
determinesifthefieldstrengthhasrisentoalevelthatwouldindicatethattheindividualis
approachinga“WarningZone”orisina“DangerZone”duetobeingtooclosetothevehicleor
machinery.IftheSurfacePADdeterminesthattheindividualistooclosetothevehicleor
machinery,itgivestheindividualbothavisualandaudibleindication.Atthesametime,the
PADtransmitsa916.48MHzRFsignaltoinformthevehicleormachinerythattheindividualis
approachingtooclose.IftheSurfacePADdeterminesthatthefieldstrengthindicatesthatthe
individualisnotinaWarningorDangerZonearea,itwilltransmitadatapacketevery10
secondsviathe916.48MHzwithitsstatuscondition.
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TheSurfacePadisanassemblycomprisedoffoursystemseachonaseparateprintedcircuit
board.ThePADSystemBoardcontainsthreemagneticfieldpick‐upcoilseachinaphysically
diferentaxisplace90degreesfromeachother.Thesepick‐upcoilsalongwiththeirfixedvalue
capacitorsandamplifiersforma73kHzreceiverforreceptionoffieldsgeneratedbyvehiclesor
machineryequipedwiththeHazardAvertsystem.TheSystemBoardalsohasaPIC
microcontrollerwhichreceives
theinputsfromthreedetectorswhichindependantlydetectthe
inputsfromthethree73kHxpick‐upcoils.ThePICthroughaninternalalgorithm,determinesif
the73kHzfiledisaboveapre‐programmedthreshold.
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IfthePICdeterminesthatthereceivedfieldisabovethethresholdlivel,itsendsalogicsignal
anddatatoaninternalRFTransmitterBoard.TheRFTransmitterBoardcontainsaLINXTXM‐