What type completes two vertical scan periods to produce one complete picture called a frame?

What type completes two vertical scan periods to produce one complete picture called a frame?

• A. Raster
• B. Plan Position Indicator (PPI)
• C. A-scan
• D. C-scan

Answer: (A)

Understanding how radar displays build an image helps here. A raster-type display forms the picture by sweeping horizontal lines across the screen and advancing vertically line by line. To create a full image, the display can use two interlaced fields (two vertical scans) that together make one complete frame. This interlacing reduces flicker and provides a stable picture, with each field contributing half the lines and both fields composing the full frame. So the description fits a raster display, where two vertical scans (two interlaced fields) combine to produce a complete frame. Other display types don’t rely on this interlaced field approach: a Plan Position Indicator uses a circular sweep for azimuth planning, an A-scan shows amplitude versus time on a single trace, and a C-scan gives a plan-view image but not formed from interlaced vertical fields to create a frame.

Understanding how radar displays build an image helps here. A raster-type display forms the picture by sweeping horizontal lines across the screen and advancing vertically line by line. To create a full image, the display can use two interlaced fields (two vertical scans) that together make one complete frame. This interlacing reduces flicker and provides a stable picture, with each field contributing half the lines and both fields composing the full frame.

So the description fits a raster display, where two vertical scans (two interlaced fields) combine to produce a complete frame. Other display types don’t rely on this interlaced field approach: a Plan Position Indicator uses a circular sweep for azimuth planning, an A-scan shows amplitude versus time on a single trace, and a C-scan gives a plan-view image but not formed from interlaced vertical fields to create a frame.