Specifications

13. Calibrating for Digital Measurement
USN52 L Operating Manual Page 91
By positioning the gate bars, a and b on opposite sides of the
midline (above and below), thinner measurements may be enabled
by setting b-START to a smaller value.
The advantage of the RF display in applications of this type can be
seen in the following idealized illustration.
The two echo signals shown are typical of many applications using
a highly damped delay line transducer to inspect very thin materi-
als.
Although the echoes are partially merged, their primary half-cycles
are on opposite sides of the midline. A delamination in a multi-
layered material may produce this type of display presentation.
Positioning gates a and b as shown allows measurement between
corresponding flanks of the two echoes, even though they are very
close together.
NOTES:
1. Adjustment range for a-THRESH and b-THRESH are as
follows (- = below midline):
+5% to +45%
-5% to -45%
2. RF mode cannot be enabled if display range exceeds 11.65
inches of steel (50µs).
3. The screen blanks momentarily when switching in and out of
RF display mode.