VLF transmitter DHO38
The VLF transmitter DHO38 (known as VLF/MSK Marinefunksendestelle Rhauderfehn or Marinefunksendestelle Saterland-Ramsloh)<ref name="nwz">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> is a very low frequency (VLF) transmitter used by the German Navy near Rhauderfehn, Saterland, Germany. It is used to transmit coded orders to submarines of the German Navy and navies of other NATO countries.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
DHO38 has transmitted since 1982 on 23.4 kHz with a power of up to 800 kilowatts, although other sources says 300kW is the usual power.<ref>Template:Cite journal</ref> Each mast is powered by 100kW transmitter but all masts operate at once.<ref name="esut">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> The transmitter is able to transmit signals in a range from 14 to 50 kHz.<ref name="bundes">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> DHO38 uses an umbrella antenna which is carried from eight steel tube masts each with a height of Template:Convert. Each pylon stands on three-metre-tall ceramic cylinders, which serve as insulators for voltages up to 300 kV.<ref name="bundes" /> The masts are equipped with cylindrical oscillation dampers for better protection against storms.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
Each mast has an antenna tuning hut and sits on a copper mat 30cm under the ground. The site is wet which helps improve the performance of the antenna.<ref name="nwz" /> The transmitter is capable of transmitting signals to submarines worldwide to depths of approx. 30 metres.<ref name="bundes" />
In 2016 the transmitters were updated to semi-conductor technology from the previous valve based ones.<ref name="esut" />
TransmissionEdit
The signal from DHO38 is an MSK-coded signal with 4 x 50 baud on all 4 channels on frequency 23.4 kHz.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> All transmissions from DHO38 are encrypted. The messages transmitted via DHO38 are processed at the naval telecommunications center Glücksburg. They are sent "by cable" from German and NATO offices to the protective structure there and are prepared for transmission by the responsible telecommunications operators.<ref name="bundes" />
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