Small aircraft receivers E 40, E 160, and C 1916 at the aircraft ground receiving station IoA (Inspection of the Aircraft)

The setup of flying squadrons during the First World War simplified not only reconnaissance but also artillery targeting. In 1915, Siemens & Halske began to build the receivers in the AE series, which received radio-telegraphic signals from special aircraft transmitters. Crystal detectors made of pyrite, silicon, or molybdenum were used to receive the signals.