Sonne (navigation)

Sonne (German for "sun") was a radio navigation system developed in Germany during World War II. It was developed from an earlier system known as Elektra, and therefore the system is also known as Elektra-sonnen. When the British learned of the system they started using it as well, under the name Consol, meaning "by the sun".

Elektra was updated version of the beam-based low-frequency radio range (LFR) used in the United States during the 1930s. This was further modified to create Sonne by electronically rotating the signal to create a series of beams sweeping across the sky. Using simple timing of the signal, the navigator could determine the angle to the station. Two such measurements then provided a radio fix. Accuracy and range were excellent, with fixes around ¼ of a degree being possible at 1,000 miles range.

Sonne was so useful that it found widespread use by UK forces as well, and they took over operation after the war. The system was used for long-range navigation under the Consol name, and supported by ICAO as one of the suggested long-range air navigation systems. New stations were constructed around the world over the next twenty years. The system remained in partial use into the 1990s, with the last transmitter in Norway turned off in 1991.

In navigation, the determination of a "fix" requires two measurements to be taken. Using classical methods, this was normally the measurement of two angles, or bearings, along the line-of-sight to prominent landmarks, like a lighthouse. After taking the two measurements, lines of position are drawn radiating from the landmarks along the reverse angle. The lines will cross at some point, and their intersection determines the location of the navigator.

The introduction of portable radio systems in the early 20th century gave rise to the possibility of using radio broadcasters (beacons) as a landmark that would be visible to a radio receiver at very great ranges, hundreds of miles or more. The angle between the navigator and the beacon can be measured by using a simple mechanism known as a loop antenna. As the antenna is rotated around a vertical axis, the strength of the received signal varies, and drops to zero (the null) when the loop is perpendicular to the line to the beacon.

...
Wikipedia