German radio intelligence operations during World War II

The German Radio Intelligence Operation were signals intelligence operations that were undertaken by German Axis forces in Europe during World War II. In keeping with German signals practice since 1942, the term "communication intelligence" (German: Nachrichtenaufklärung) had been used when intercept units were assigned to observe both enemy "radio and wire" communication. When the observation of only enemy "radio" communication was undertaken, the term was "radio intelligence" (Funkaufklärung).

Source: Wikipedia — German radio intelligence operations during World War II (CC BY-SA 4.0)