OPERATION MANUAL - Scintrex

Compensation and CorrectionsTo eliminate the effects of instrument drift, a drift correctionDC() t = ( t – t s) DRIFT(B.13)is subtracted from each uncorrected sample SU.DRIFT is the drift constant with units of mGal/24hrs, t s , is the driftcorrection start time and t is the time at which the samples are taken. BothDRIFT and ts are entered via the keypad.With the drift correction applied, Equation (B. 12) becomes:Rt ( 2 )–Rt ( 1 ) = RU( t 2 )– DC( t 2 )– RU( t 2 ) + DC( t 1 )=( dt ( 2 – t 1 )–DRIFT( t 2 – t 1 ))(B.14)If the drift correction is properly adjusted:DRIFT=dRt ( 2 ) – Rt ( 1 ) = 0(B.15)The procedure for adjusting the drift correction is given in the Maintenancesection starting on page 5-15.TheoryTilt Correction (TIC)The uncompensated gravity reading changes in response to tilt according tothe following expression:RU( θ x, θ y) = RU( 0,0) – g( 1 – cosθ x⋅ cosθ y)(B.16)2. calculation precision limits the maximum of (t-ts) to 4 months (128 days)B-17CG-5 Manual - part # 867700 Revision 2