GE Ultrasonic USM Go Operator's Manual page 127

3.16.2a Interpreting JISDAC Lines and Classes
The JISDAC display contains a recorded reference line and five fixed offset lines. Three of the lines are labeled as follows:
H Line – Connects the recorded reference points
•
M Line – Fixed offset positioned 6 dB below the H line
•
L Line – Fixed offset positioned 12 dB below the H line
•
Any one of these three lines can be identified as the reference from which measurements are based (see the BOLD LINE function below). In
addition, the remaining three offset lines are drawn at 6, 12, and 18 dB above the H line.
The regions of the A-Scan display bordered by the H, M, and L lines are identified with JIS Class numbers. These identifying numbers can
also be displayed as results. CLS reports the region that contains the peak of the Gate A triggering echo.
USM Go Operator's Manual
Chapter 3. Making Measurements
109