Which term describes the horizontal movement across the screen in an A-scan instrument?

Which term describes the horizontal movement across the screen in an A-scan instrument?

• A. A square wave pattern
• B. A marker pattern
• C. A sweep line
• D. None of the above

Answer: (C)

In an A-scan display, time of flight is laid out along the horizontal axis while signal amplitude sits on the vertical axis. As the transducer sends pulses and echoes return, the trace moves from left to right, creating a sweeping line across the screen. This horizontal progression is known as the sweep line, and it represents the passage of time (and thus distance to reflectors). The other terms describe different ideas—square wave pattern is about waveform shape, not the display motion, and a marker pattern refers to measurement marks rather than the display’s motion. So the sweep line best captures the moving horizontal display in an A-scan.

In an A-scan display, time of flight is laid out along the horizontal axis while signal amplitude sits on the vertical axis. As the transducer sends pulses and echoes return, the trace moves from left to right, creating a sweeping line across the screen. This horizontal progression is known as the sweep line, and it represents the passage of time (and thus distance to reflectors). The other terms describe different ideas—square wave pattern is about waveform shape, not the display motion, and a marker pattern refers to measurement marks rather than the display’s motion. So the sweep line best captures the moving horizontal display in an A-scan.