An alpha scan radar is typically displayed on a PPI.

• A. Circular display
• B. PPI
• C. Sector PPI
• D. Plan Position Indicator

Answer: (B)

Alpha scan radar is most effectively represented in a plan view that shows both bearing and range in a single circular picture. This is what a Plan Position Indicator provides: a circular display with the radar at the center, range rings outward, and targets plotted by their angle around the circle and their distance from the center. The rotating beam of the alpha scan creates a real-time map of the surroundings, so presenting it on a PPI gives a intuitive, map-like view of where things are relative to the own ship or radar location. The expanded term, Plan Position Indicator, describes the same display that the shorthand PPI refers to, which is why that option is the best choice. A circular display describes the shape, but the term PPI specifies the actual radar display format, and a sector PPI would imply only a partial circle rather than the full 360-degree view typical of alpha scan radar.