In an A-mode display, which pair of measurements is commonly shown?

In an A-mode display, which pair of measurements is commonly shown?

• A. Amplitude and reflector distance
• B. Time and velocity
• C. Frequency and amplitude
• D. Phase and distance

Answer: (A)

A-mode shows echoes as spikes where depth is mapped along the horizontal axis and the height of each spike represents the echo’s amplitude. So the display conveys how strong the reflected signal is (amplitude) and how far away the reflector is (distance, derived from the echo’s round-trip time). That combination—echo amplitude and reflector distance—is what A-mode presents. The other ideas don’t fit this one-dimensional, spike-based display: Doppler-type measures involve velocity, spectral content uses frequency and amplitude, and phase/distance isn’t the standard pair shown in A-mode.

A-mode shows echoes as spikes where depth is mapped along the horizontal axis and the height of each spike represents the echo’s amplitude. So the display conveys how strong the reflected signal is (amplitude) and how far away the reflector is (distance, derived from the echo’s round-trip time). That combination—echo amplitude and reflector distance—is what A-mode presents. The other ideas don’t fit this one-dimensional, spike-based display: Doppler-type measures involve velocity, spectral content uses frequency and amplitude, and phase/distance isn’t the standard pair shown in A-mode.