Specifications

Page 76 USN52 L Operating Manual
NOTE: Reference and discontinuity echoes cannot exceed
127% screen height. This is the maximum amplitude that
can be evaluated.
The reference echo must be the highest amplitude signal in the
gate, as illustrated below.
During inspection, when a signal violates threshold in the gate, the
H= value displayed in the measurement line indicates its ampli-
tude in dB relative to the reference echo. Echo signals lower in
amplitude are shown as negative (-) values. Signals higher than
the reference amplitude are shown as positive (+) values.
The following illustration shows a discontinuity signal at 90% of full
screen height relative to the 80% reference echo. The value H=+1.0
dBR shows that the discontinuity echo signal exceeds reference
amplitude by 1.0 dB.
Changing GAIN while dB REF is enabled does not affect the dis-
played H= value. Incremental gain values are shown in the GAIN
function box as explained in Section 12.1.
12. Using db REF
3. Activate dB REF and store reference echo amplitude and
reference GAIN by pressing
.
All subsequent echoes in the gate will be compared against
the reference echo.