Specifications

13. Calibrating for Digital Measurement
USN52 L Operating Manual Page 89
gate b starts 0.030 inch beyond the leading edge of gate a when
no signal is in the gate, as illustrated below.
False readings are often caused by excessive ringing of the first
echo or nonrelevant signals between the first and second backwall
echoes. The b-START feature prevents false readings by block-
ing the measurement during the b-START interval immediately after
the first measurement echo.
11. Set b-START as close as possible to the trailing edge of the
first measurement echo:
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.