Waveforms received by the transducer are digitized and stored. These data are presented in a variety of formats for interpretation by the operator. Common presentations include A-scans, displaying a single waveform, and sectorial scans, displaying the results of multiple waveforms combined to form a color-coded image.
The A-scan display shown in figure 5 presents waveform amplitude versus time, the typical data presentation for conventional ultrasonic pulse-echo technologies.
A sectorial scan displays a color representation of wave amplitudes detected by the transducer. The display is formed from the combination of numerous A-scans captured as the beam is steered at different angles. To form the sectorial scan, the amplitude of each data point in an A-scan is assigned a color from a defined color palette (shown to the right of the sectorial scan in figure 5). The color representation of the amplitude of each individual A-scan produced as the wave beam is steered through the desired angles is then plotted. Using this graphical representation, indications that cause high amplitude reflections as the wave beam is steered through the desired angles appear as two-dimensional features on the sectorial scan.
Data may also be presented in a C-scan format when a two-dimensional scanner is used to scan the transducer across the surface of the material being tested. The C-scan format presents the linear ordinate of the transducer on the x-axis and the color-coded amplitude of the A-scans across the transducer aperture plotted on the vertical axis. A spatial image showing areas of section loss and/or deep corrosion pits is produced.