What does the origin of the PPI sweep represent?

The origin of the PPI (Plan Position Indicator) sweep represents ownship, which is the position of the vessel or vehicle that is using the radar system. In radar displays, ownship is depicted at the center of the display, and all radar information (such as targets and landmasses) is shown relative to that central point. This allows operators to easily identify their surroundings and assess target positions in relation to their own location.

For radar operators, understanding the position of ownship is crucial for navigation and situational awareness. The sweep on the PPI rotates around ownship, updating the display to provide a real-time depiction of the surrounding environment. This central positioning helps in accurately interpreting data regarding nearby vessels, obstacles, and navigational hazards.