OPERATION MANUAL - Scintrex

The uncorrected sample has drift correction and GREF applied and ifselected, then also the tilt correction, to give a corrected sampleS = SU - DC + GREF + TIC = SU + C(B.5)A running average of corrected samples (the function Σ in Figure B-2 onpage B-3) gives the corrected reading(B.6)RU ij=y x⎛SF ij ⎞ ⎛SF ij ⎞∑ ∑2 GCAL1⎜----------⎟ + GCAL2⎜----------⎟ + C⎝SC j ⎠ ⎝SC j ⎠ ijj------------------------------------------------------------------------------------------------------------------------------= li= 1=( j–1)x+i–NRy x∑∑( S ij+ C ij)--------------------------------------------------j = li= 1DURWhere SCj is the value of the jth voltage calibration and SF ij and C ij are theith gravity sample and correction after the jth voltage calibration.** Standard deviation —The standard deviation (SD) of the corrected samples is calculated everysecond and samples which are more than four standard deviations from RU ijare rejected. This AUTO REJECT feature can be disabled via the keypad.The SD is displayed every time except when the instrument calibrates itself,e.g. every 12 seconds, if CAL AFTER value 12 is selected, then the error(ERR) is displayed. It is recorded and output, as well. It is the measure ofsignal noisiness, which includes the instrumental and ambient seismic noise.The current value of RU ij is shown on the top line of the display during thereading period and the current sample numberDUR = (j - 1)x + i - NR(B.7)where NR is the number of rejections. On the right hand side of the secondline the display alternates between the latest value of the ERR duringcalibration sampling and the standard deviation of the mean. ERR isestimated under the assumption that the noise during gravity sampling isnormally distributed (i.e. white) from the relationship:ERR=SD-----------------DUR(B.8)B-10CG-5 Manual - part # 867700 Revision 2