OPERATION MANUAL - Scintrex

g is the value of gravity at the reading site and θ x and θ y are the tilts of thegravity sensor about two horizontal axes (x and y) with θ x and θ y = 0 beingdefined as the orientation in which the uncompensated gravity meter ismaximized.The tilt correction operates over a range of +/- 200 arcsec and is:TIC=g t( 1 – cosθ x⋅ cosθ y)(B.17)where g t is an average sea level gravity of 980.6 Gal and X and Y are theindicated gravity meter tilts.Assuming g t = g (this assumption leads to an error of 0.002 mGal in the worstcase), the corrected reading value will be:RU( θ x, θ y) = RU( 0,0) – g t( cosθ x⋅ cosθ y– cosx⋅ cosy)(B.18)Ifx = θ x(B.19)y = θ ythenRU( θ x, θ y) = RU( 0,0) = 0(B.20)and errors due to instrument tilt are eliminated. The method used to adjust Xand Y so that equation (B.19) is satisfied is given in the Maintenance sectionstarting on page 5-17.There are two selectable modes of operating the tiltcorrection:1. (CONT. TILT CORR - SELECTED), a correction is applied to each onesecond sample.2. (CONT. TILT CORR - DISABLED), a correction is only applied at theend of the reading based on the X and Y values of the last one secondB-18CG-5 Manual - part # 867700 Revision 2