The solution to night intercepts would be provided by Dr . W . B . " Ben " Lewis, who proposed a new, more accurate ground control display, the Plan Position Indicator ( PPI ), a new Ground-Controlled Interception ( GCI ) radar, and reliable AI radar.
32.
Usually they operate pointing to the zenith, but an increasing number of them have nowadays scanning units, that allow to retrieve additional information such as volume information when performing various Range Height Indicator ( RHI ) scans at different angles and at a relatively high speed, and vertical wind profiles, when performing Plan Position Indicator ( PPI ) at few degrees from the zenith.
33.
"' Jagdschloss "', officially the "'FuG 404 "', was the designation of a early warning and battle control radar developed just prior to the start of World War II . Although it was built in limited numbers, Jadgschloss is historically important as the first radar system to feature a plan position indicator display, or " PPI ".
