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Chapter 3. Making Measurements
3.6
Freezing the A-Scan Display
By using the FUNCTION1 or FUNCTION2 functions in the SETUP menu, you can program one end of the Function Toggle to FREEZE
the display. Then, whenever an A-Scan is active, pressing that end of the Function Toggle freezes the A-Scan display. The active A-Scan
will remain as it appeared when the toggle was pressed and the display will remain frozen until it is pressed again. While the display is
frozen, the displayed readings are based on the frozen echoes.
3.7
DAC/TCG Evaluation Mode (Optional)
Note: Optional evaluation features, such as DAC/TCG, are selected via the EVAL MODE function in the EVAL menu. The functions for
the selected evaluation mode then appears in the ACQUIRE menu.
Conventional measurements can be made using the Time Corrected Gain (TCG) and Distance Amplitude Correction (DAC) modes. The
functions for these modes are accessed through the DAC/TCG menu on the ACQUIRE menu bar. The DAC and TCG modes operate based
on a set of user-recorded data points. These points are recorded from the DAC/TCG menu as described below.
The TCG mode displays reflectors of equal size at equal A-Scan amplitudes, regardless of the depth of the reflector in the test material. This
is accomplished by adjusting the gain at different locations in the A-scan display, corresponding to different material depths, to compensate
for signal loss (or variation) due to attenuation, beam spread, or other factors.
The DAC mode displays all echoes at their true amplitude, without depth compensation. However, when operating in DAC mode, a
Distance Amplitude Correction curve is superimposed on the A-Scan display. The curve represents the constant reflector size at varying
material depth.
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USM Go Operator's Manual
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