Specifications

11. Using DAC/TCG
USN52 L Operating Manual Page 75
12.1 Description of dB REF
dB REF stores, as a reference echo, the amplitude of the highest
echo signal in the gate for comparison against echoes from
discontinuities.
Reference and incremental gain values are also stored and dis-
played in the GAIN function box, as shown below. Note that the
incremental gain value replaces the word “GAIN”.
Reference GAIN is the instrument gain setting at the time dB REF
is enabled.
Incremental GAIN shows any change, relative to reference gain,
since dB REF was enabled. A positive value (+xx.x dB) indicates
an increase. A negative value (-xx.x dB) indicates a decrease in
the GAIN setting.
When dB REF is enabled, the H= value in the measurement line
shows the amplitude of the highest echo in the gate as “+xx.x dBR”
or “-xx.x dBR” relative to the reference echo. A positive (+) value
indicates that the discontinuity echo is higher in amplitude than the
reference echo. A negative (-) value means the discontinuity sig-
nal is lower in amplitude.
12.2 Using dB REF
Calibrate the A-scan display (Chapter 9), and set gate delay, width,
and threshold according to test requirements (Chapter 10). Acti-
vate the measurement line by setting the MEASURE function
(MEAS menu) to 0 TO 1st. Then proceed as follows:
1. Couple the probe to the reference block or test piece and
optimize the reference echo.
2. Use GAIN to adjust the reference echo signal to the desired
amplitude:
12. Using dB REF