Decimeter telegraphy
Decimeter telegraphy is the German code designation for all efforts by German engineers and specialists in the development of a radar device before and during the Second World War .
As early as September 26, 1935 , Rudolf Kühnhold presented the High Command of the Navy with a radio measuring device based on the principle of transmitting electromagnetic waves and receiving the resulting echo waves . In the experiment, the training ship Bremse served as the target object and was successfully measured by a radio measuring device that had 40 watts at a wavelength of 48 cm . Based on the good results, it was decided to further develop the process.
Since the development was subject to the highest level of secrecy , it was decided to use the less captivating and descriptive term decimeter telegraphy for the term “ radio measurement ” or for research work on sea and air reconnaissance with electromagnetic waves .
The devices based on the principle of decimeter telegraphy were thus called DeTe devices . Due to the high level of secrecy of the project, this abbreviation was misinterpreted as German technical device.
The research work of Kühnhold and GEMA , the Society for Electroacoustic and Mechanical Apparatus, which he co-founded in 1934 , progressed quickly and well, so that as early as 1935 a DeTe device was produced with a range of 20 km. Since the Air Force was now also interested in the new technology, special DeTe devices for aerial reconnaissance , called Freya devices, were also developed . Here the prototype in 1937 already achieved a range of 200 km at a wavelength of 240 cm.