Kurzsignale

The method of defining U-boat meeting points in the Short Signal Book was regarded as compromised, so a method was defined by B-Dienst cryptanalysts to disguise their positions on the Kriegsmarine German Naval Grid System (German:Gradnetzmeldeverfahren) was introduced and used until the end of the war[1] Aware of the danger presented by radio direction finding (RDF), the Kriegsmarine developed various systems to speed up broadcast.

The resulting Kurzsignal was then encoded with the Enigma machine and subsequently transmitted as rapidly as possible, typically taking about 20 seconds.

[2] Conventional RDF needed about a minute to fix the bearing of a radio signal, and the Kurzsignale protected against this.

The fully automated burst transmission Kurier system, in testing from August 1944, could send a Kurzsignal in not more than 460 milliseconds; this was short enough to prevent location even by huff-duff and, if deployed, would have been a serious setback for Allied anti-submarine and code-breaking activities.

By late 1944 the Kurier program was a top priority, but the war ended before the system was operational.