Specifications

13. Calibrating for Digital Measurement
USN52 L Operating Manual Page 85
8. Select b-THRESH by simultaneously pressing aligned
with a-THRESH.
9. Adjust b-THRESH, gate b threshold level:
When TOF mode is FLANK, measurement is determined by
the point where each signal’s leading edge (flank) crosses
gate threshold level. In the A-scan, this corresponds to the
intersection of the signal flank and gate bar.
Since the second echo is typically lower in amplitude than the
first, gate b threshold should be set so that points of inter-
section correspond, as shown in the illustration below.
b-START is set as a percent of the current a-WIDTH setting. For
example, if a-WIDTH is 0.300 inch and b-START is 10%, then
gate b starts 0.030 inch beyond the leading edge of gate a when
no signal is in the gate, as shown in the following illustration.
When an echo signal occurs in gate a, the start of gate b automati-
cally changes to the b-START interval after the first echo in gate a.
In the example above, an echo signal at 0.040 inch in gate a causes
gate b to start 0.030 inch (10% of a-WIDTH)) after the first echo in
gate a, or at 0.070 inch. This is shown in the next illustration.
10. Select b-START by simultaneously pressing aligned
with a-START.