DMTA-10004-01EN, Rev. D, November 2016
Chapter 13
230
Figure 13‑8 The TDG zones and parameters
You can use the TDG curve to optimize near-surface resolution while providing a
higher maximum gain for thicker samples. You can also use the TDG curve in
measurements of highly scattering materials, such as cast metals and fiberglass, to
minimize detection of scattered echoes occurring ahead of the back-wall echo.
13.6.1 Maximum Gain
The maximum gain indicates the maximum (time-dependent) receiver gain possible.
The maximum gain is used to amplify echoes that are further out in time. In general
for a given application, you should set the maximum gain high enough so that all
echoes of interest are detected.
You can adjust the maximum available receiver gain from 0.0 dB to 99.0 dB. When no
echo is detected (LOS prompt), the gain rises to the maximum level set by the initial
gain, slope, and maximum gain. When the maximum gain is set too high, the gage
may hang up on transducer noise or other spurious signals; when it is set too low,
returning echoes may not be high enough for detection.
Time-dependent gain
curve
INIT GAIN level zone
MB BLANK
MAX GAIN
level zone
TDG SLOPE zone
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