GE MFE DMS 2 Operating Manual page 130

4. Measuring Thickness
FIGURE 4-13—In the DUAL and SIP measurement modes, material thickness is calculated based on the amount of time it
takes for the first returning sound pulse (echo) to cross the A-gate. When the DSM 2 is operating in these measurement
modes, the B-gate won't be visible. In the S-FLANK Mode, the material thickness is calculated based on the time between the
first returning pulse that crosses the A-gate, and the next pulse that crosses the B-gate. In S-PEAK and Dual-Multi modes,
material thickness is calculated based on the time between the peaks of the largest echoes crossing the A-gate and B-gate.
DMS 2 Operating Manual Page 119