This is the result of “auto depth-adjustment. With auto-depth adjustment turned on, DigiPro1 correctly plot data points at the top (or bottom) of the measurement interval. Auto-depth is turned on by default.
Why is an adjustment provided? Depth marks on Digitilt control cable are measured from the middle of the inclinometer probe, but deviations and displacements are calculated for the top (or bottom) of an interval.
Metric example: The depth stored with the inclinometer reading is the cable depth of 20 meters, but the top of the interval is actually at 19.75 meters. With auto-depth adjust turned on, the plotted point will be placed correctly on the graph at 19.75 meters, rather than at the cable depth of 20 meters.
English example: The depth stored with the inclinometer reading is the cable depth of 60 feet, but the top of the interval is actually at 59 feet. With auto-depth adjust turned on, the plotted point will be placed on the graph at 59 feet, rather than at the cable depth of 60 feet.