Brunson 771 - Field Calibration Checks

35 Operation and Adjustment Manual
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Yourtransitiscapableofestablishingextremelyaccurategeometric
relationshipsbetweenvariouspoints,lines,andplanes.Inorderto
doso,anumberofparametersonthetransitmustbeperiodically
maintainedandadjusted.Theneweratransitis,themoreoften
thatcalibrationandadjustmentisrequired.Asyourtransitages,
andthestressesofmanufactureandinitialcalibrationslowlywork
themselvesout,itwillbecomemorestable.Alsoplayingavery
largeroleareyourpatternsofusageandtheenvironment(s)in
whichyourtransitisstoredorused.Soinitially,youmaywishto
testyourtransitmorefrequentlysothatyoucandeterminehowit
isrespondingtoyourparticularsituation.
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Youcanperformthefieldcalibrationchecks(andsomeofthead‐
justments)yourselfifyouhavethedesireandafewrequireditems.
Thesearechecksandadjustmentsthatyoucandointhefieldwith‐
outanyspecializedcalibrationequipment.Theyareasubsetofthe
checkswhichconstituteafullcalibrationprocedure.Itisn’tabad
ideatotestoutyourinstrumentusingthesefieldchecksaftership‐
menttoajobsite.
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Foreachtestoutlinedinthischapter,wewilldescribefivethings:
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1. Theintendedresult—wewilldescribewhatyouaretry‐
ingtoaccomplish.
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2. Theachievabletolerance.
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3. The“affectedparameters”.Someoftheadjustmentsthat
mustbemademayaffectotheradjustments(thisphe‐
nomenonisalsocalled“cross‐coupling”).Therefore,af‐
teraccomplishinga
particularadjustment,youmustgo
backandcheckthe“affectedparameters”andmakesub‐
sequentadjustmentsifnecessary.Notethatsometransit
adjustmentsaremutuallydependentandrequirearepeti‐
tiveapproach.Thatis,twoormoreadjustmentsmayaf‐
fecteachother,requiringthatyoumakesequentialad‐
justmentsof
allaffectedparameters.Whensuccessfully
accomplished,eachsubsequentadjustmentissmaller
thanthelast,untilallparametersarewithintolerance.
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4. Itemsrequiredtocompletethetest,ifany.Forexample,
someofthefieldadjustmentsrequirescalesorotherim‐
promptutargetingbemadeavailable.
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5. Properadjustment
procedures.
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Thefollowingfieldtestswillbediscussedinthischapter:
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Chapter4‐FieldCalibrationChecks
Werecommendthatyou
haveyourtransitfully
cleanedandcalibratedat
leastonceayear.