Figure 5-24. CRT Display Before Adjusting Sweep Delay.
The Sweep Length/Range control determines how much time/distance is represented by the sweep on the display. In
Figure 5-25, if the Sweep Length/Range is adjusted to decrease the time/distance represented (that is, the sweep
length/range), the spacing between the signals will increase, as seen in Figure 5-26. Note that the front surface signal
did not move; only the distances between the front surface signal and the other signals increased. Referring back to
Figure 5-23, the four-inch length of the test part and the one-inch depth of the discontinuity are represented by the
signals in Figure 5-26 at 4 and 1 respectively. In other words, the Sweep Length/Range control is used to calibrate
the time base to the test part using the horizontal scale on the display.
Figure 5-25. CRT Display After Adjusting Sweep Delay.
Figure 5-26. Effect of Sweep Length on CRT Display.