Plan position indicator

The PPI display was first used prior to the start of the Second World War in a Jagdschloss experimental radar system outside Berlin.

The first production PPI was devised at the Telecommunications Research Establishment, UK and was first introduced in the H2S radar blind-bombing system of World War II.

Originally, data was displayed in real time on a cathode-ray tube (CRT), and thus the only way to store the information received was by taking a photograph of the screen.

Philo Taylor Farnsworth, the American inventor of all-electronic television in September 1927, contributed[citation needed] to this in an important way.

In meteorology, a competing display system is the CAPPI (Constant Altitude Plan Position Indicator) when a multi-angle scan is available.

Image of a thunderstorm line (in dBZ) seen on a 0.7-degree elevation PPI ( NOAA )
Diagram showing the evolution of the height above ground, in kilometers, with the distance to the radar for the 24 PPI angles used on the Canadian weather radars (curved lines)
A photograph of an H2S PPI display taken during an attack on Cologne . The annotations were added later for post-attack analysis. The Rhine River can clearly be seen.
Simplified animation of a Plan Position Indicator radar display