What occurs on the CRT face of the PPI display each time a radar pulse is transmitted?

Each time a radar pulse is transmitted, a sweep from the center to the outer edge of the CRT face occurs in a Plan Position Indicator (PPI) display. This is integral to how radar systems visualize the data they gather.

When the radar pulse is emitted, it travels outward, and the return echoes from objects and surfaces are detected by the radar receiver. The radar system then processes the time it takes for these echoes to return in order to determine the distance to the objects. This information is represented visually on the display as a sweep.

The sweep starts at the center of the screen, corresponding to the radar's own location, and radiates outward to represent distance. The entire circumference of the CRT face is utilized to show various ranges and angles, creating a comprehensive view of the area around the radar source. By performing this radial sweep, the display is able to update the positions of detected objects in real-time as new radar pulses are transmitted.

This process does not involve a complete reset of the display or refreshing in the conventional sense but is more about generating a continuous and dynamic representation of the radar data. Thus, the correct answer highlights a fundamental aspect of how the radar information is visually transmitted to the operator through the CRT display.