Sonne (German for "sun") was a
radio navigation
Radio navigation or radionavigation is the application of radio frequencies to determine a position of an object on the Earth, either the vessel or an obstruction. Like radiolocation, it is a type of radiodetermination.
The basic principles a ...
system developed in Germany during
World War II
World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposing ...
. It was developed from an earlier experimental 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 an updated version of the beam-based
low-frequency radio range
The low-frequency radio range, also known as the four-course radio range, LF/MF four-course radio range, A-N radio range, Adcock radio range, or commonly "the range", was the main Radio navigation, navigation system used by aircraft for instrument ...
(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 In telecommunication and position fixing, the term radio fix has the following meanings:
*The locating of a radio transmitter by bearings taken from two or more direction finding stations, the site of the transmitter being at the point of intersec ...
. Accuracy and range were excellent, with fixes around ¼ of a degree being possible at 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.
Background
![Visual-fix-by-three-bearings](https://upload.wikimedia.org/wikipedia/commons/d/dd/Visual-fix-by-three-bearings.png)
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
A position line or line of position (LOP) is a line (or, on the surface of the earth, a curve) that can be both identified on a chart (nautical chart or aeronautical chart) and translated to the surface of the earth. The intersection of a minimum o ...
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. In practice, a third measurement is often used, resulting in three lines that do not perfectly intersect; the size of the resulting triangle intersection area gives a rough indication of the accuracy of the measurement as a whole.
RDF
The introduction of portable
radio
Radio is the technology of signaling and communicating using radio waves. Radio waves are electromagnetic waves of frequency between 30 hertz (Hz) and 300 gigahertz (GHz). They are generated by an electronic device called a transmi ...
systems in the early 20th century gave rise to the possibility of using radio broadcasters (''
beacon
A beacon is an intentionally conspicuous device designed to attract attention to a specific location. A common example is the lighthouse, which draws attention to a fixed point that can be used to navigate around obstacles or into port. More mode ...
s'') 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
A loop antenna is a radio antenna consisting of a loop or coil of wire, tubing, or other electrical conductor, that is usually fed by a balanced source or feeding a balanced load. Within this physical description there are two (possibly three) d ...
. 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.
[Joseph Moell and Thomas Curlee, "Transmitter Hunting: Radio Direction Finding Simplified", TAB Books, 1978, pp. 1–5.]
This technique, known as
radio direction finding (RDF), is useful but only moderately accurate. Measurements better than a few degrees are difficult with a small loop antenna, and because of the electrical characteristics, it is not always easy to make a larger version that might provide more accuracy. Moreover, the addition of a loop antenna may not be possible on smaller vehicles, or difficult to operate for those without a dedicated navigator.
[
There were some experiments with a sort of "reversed" version of the RDF concept. Among these was the British ]Orfordness Beacon
The Orfordness Rotating Wireless Beacon, known simply as the Orfordness Beacon or sometimes the Black Beacon, was an early radio navigation system introduced by the United Kingdom in July 1929. It allowed the angle to the station to be measured ...
which broadcast a signal from a loop that was continually rotating at 1 rpm (6 degrees a second). Every time the loop passed north it would briefly transmit the Morse code signal for the letter "V". Users would listen for the V signal and then begin a stopwatch
A stopwatch is a timepiece designed to measure the amount of time that elapses between its activation and deactivation.
A large digital version of a stopwatch designed for viewing at a distance, as in a sports stadium, is called a stop clock. ...
, waiting for the signal to disappear as the loop rotated past them. The elapsed time, times six, indicated their bearing angle from the station. A second bearing to a similar station at RAE Farnborough
The Royal Aircraft Establishment (RAE) was a British research establishment, known by several different names during its history, that eventually came under the aegis of the UK Ministry of Defence (MoD), before finally losing its identity in me ...
provided a fix.
Unfortunately, in practice it was found that the system was only accurate during the day and in good weather, which limited its usefulness for its intended role of naval guidance, and the system was operational only for a brief period.
Radio Range, Lorenz and Elektra
Another solution to the radio navigation problem is to use a directional "beam" signal that can only be received in a certain area. Aircraft flying within the beam will hear the signal on a conventional radio. This presents a problem; the beam should be wide enough that an aircraft can find it, but narrow enough to be an accurate guide.
The first attempts to address this issue were made in Germany as early as 1904. O. Scheller of the Lorenz company proposed a system using four signals in an overall fan-shaped pattern. Each of the signals was modulated audibly with the Morse code signal for N (dash-dot) or A (dot-dash), so a radio tuned to the broadcast frequency would hear one of these signals. The signals deliberately overlapped slightly, so there were areas where the listener would hear both at the same time. In this case the gaps in one signal would be filled in by the other, producing a steady tone known as the "equisignal".
Several developments of this basic concept followed, but it did not become practical until World War I
World War I (28 July 1914 11 November 1918), often abbreviated as WWI, was one of the deadliest global conflicts in history. Belligerents included much of Europe, the Russian Empire, the United States, and the Ottoman Empire, with fightin ...
. By that time Germany's economy was limited and their aviation activities strictly curtailed. Practical development then moved to the United States, where it was used in modified form with two wide figure-8 shaped broadcast patterns that allowed easy capture of the signal. Instead of the short-range landing system proposed by Scheller, the US system was used to build the low-frequency radio range
The low-frequency radio range, also known as the four-course radio range, LF/MF four-course radio range, A-N radio range, Adcock radio range, or commonly "the range", was the main Radio navigation, navigation system used by aircraft for instrument ...
(LFR) system starting in 1928, offering wide-area navigation between airports
To use the system, the aircraft would tune in the station on a conventional radio. They would then listen for the signal, and depending on whether they heard the A or N, would turn until they were flying in the middle of the beam where they heard the equisignal. The system was set up so the beam pointing to the west from one station had the opposite dot-dash pattern as the one pointing east from the next, so the pilot could tune in the stations on either end of a particular leg and hear the same signal from both. As they flew from station to station they would hear the signal from one fade and the other grow, until they passed over the station where they entered the "cone of silence".
As the German economy recovered, development of the Lorenz system was picked up again in the late 1930s. Ernst Kramar was asked to develop a blind landing system more along the lines of Scheller's original concept. This emerged as a system generically known as a "Lorenz beam The Lorenz beam was a blind-landing radio navigation system developed by C. Lorenz AG in Berlin. The first system had been installed in 1932 at Berlin-Tempelhof Central Airport, followed by Dübendorf in Switzerland (1934) and others all over the ...
", which used three antennas and phasing techniques to produce highly directional signals only a few degrees wide. The transmitters were placed off the end of runways and the pilot could listen to the signals to fly down the fan-shaped signal to the runway. During World War II
World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposing ...
, even more accurate and long-range versions were used as night bombing aids; see the Battle of the Beams
The Battle of the Beams was a period early in the Second World War when bombers of the German Air Force ('' Luftwaffe'') used a number of increasingly accurate systems of radio navigation for night bombing in the United Kingdom. British scientif ...
for details.
As the German economy improved and Luft Hansa started a wider schedule, Kramar was asked to develop a system similar to LFF for use in Europe. He named this Elektra, after the character in Richard Strauss's opera of the same name. Using Lorenz beams, Elektra allowed each signal to be narrower, so a single station could provide a number of incoming and outgoing paths, instead of just four. In this way a smaller number of stations could be used in order to produce a series of airways that more directly connected airports. However, no deployment effort had taken place by the time the war started.
Sonne
Early in the war the Luftwaffe
The ''Luftwaffe'' () was the aerial-warfare branch of the German ''Wehrmacht'' before and during World War II. Germany's military air arms during World War I, the ''Luftstreitkräfte'' of the Imperial Army and the '' Marine-Fliegerabtei ...
approached Kramar to see if Elektra could be adapted to allow general navigation, rather than beam-flying. He responded by combining the beam concept from the Lorenz system with the rotating signal from the Orfordness concept, but in a unique system that represented a dramatic advance in form.
Instead of rotating a loop antenna, Sonne used three separate fixed antennas, spread along a line with each antenna 1 km from the next, a distance of three wavelengths at the 300 kHz operational frequency (several frequencies were used between 250–350 kHz). A single transmitter produced a signal that was sent directly to the centre antenna.
The signal was also split off from the main feed and sent to a "keying unit". This further split the signal into one of two paths, each connected to one of the two side antennas. The keying unit sent the signal briefly to one antenna and then for a longer duration to the second, producing the dot-dash pattern used in the Lorenz systems. As the centre and one of the two side antennas were powered at any given time, the resulting radiation pattern was a cardioid
In geometry, a cardioid () is a plane curve traced by a point on the perimeter of a circle that is rolling around a fixed circle of the same radius. It can also be defined as an epicycloid having a single cusp. It is also a type of sinusoidal ...
.
The key to the Sonne system was a further modification of the signal before it reached the antennas. A phase shifter was used to retard the signal by 90 degrees when it was sent to one of the side antennas, or advance it 90 from the other. This created a series of spikes, or lobes, within the cardioid radiation pattern, each about 7.5 degrees wide. As the antennas were physically separated, the spikes did not precisely overlap, producing the same dots, dashes and equisignal zones of the Lorenz system.
Finally, the phase delay signal was slowly "rotated". Over a period of 30 seconds, the advanced signal was retarded by 180 degrees, and the retarded signal advanced by the same 180 degrees. This caused the entire cardioid pattern to slowly rotate, dots clockwise, dashes counterclockwise.
Navigating with Sonne
Once a minute the signal to the side antennae was cut off, producing a pure tone that was broadcast omni-directionally from the centre antenna. This was keyed with a Morse code station identifier. The navigator could use this 6 second period to find the general bearing to the station using RDF. This allowed them to determine which of the lobes of the pattern they expected to be located within.
When the phase delays started up again, 2 seconds after the station identifier ended, the dot-dash keying started with it. The receiver would normally be located to one side or the other of the equisignal, so they would hear either dots or dashes - for this example lets say dots. As the pattern was rotated, the dots lobe moved away from the receiver while the dashes signal approached it. So over the 30 second period, the receiver will hear dots, then the equisignal (briefly), and then dashes. By timing the arrival of the equisignal, the navigator could determine their location within the lobe.
Whereas Orfordness required this delay to be timed on a clock, Sonne keyed the signal once per second, allowing the timing to be captured simply by counting the number of dots or dashes. To make this process even easier, a series of nautical charts
A nautical chart is a graphic representation of a sea area and adjacent coastal regions. Depending on the scale of the chart, it may show depths of water and heights of land (topographic map), natural features of the seabed, details of the coa ...
were produced with the counts listed on them. The navigator simply looked up the number on the chart to reveal the bearing.
As the pattern rotated only 7.5 degrees over 30 seconds, and the timing was accurate only to a second, the accuracy of the system was theoretically 7.5 / 30, or ¼ of a degree. In practice, during the day at 300 nautical miles, accuracies of ±½ degree were common when the receiver was located at right angles to the station's baseline, and ±1 degree at 70 degrees to the normal. Like most medium- and long-wave systems, accuracy degraded at night due to atmospheric effects, to ±1 degree on the normal and ±2 degrees at 70 degrees.
Deployment
It is a general rule in navigation that the most accurate results are measured when the two bearings are as close to 90 degrees apart as possible. As Sonne was a long-range system, it made sense to locate the stations at long distances from each other, to enlarge the area where there would be large angles between the stations.
This led to deployments starting in 1940 with two stations in Spain and one in Norway. Additional stations were added throughout the war, including examples in the Netherlands, France, Spain and Germany. A total of 18 broadcasters were eventually constructed, some referred to as Sonne and others Elektra, although the reason for this naming is not clear in modern sources.[J. van Tongeren]
"Elektra-Sonne"
/ref>
The system was compromised by the capture of the German U-boat U-505 in 1944, leading to a complete understanding of the system in the UK. This proved so useful that Sonne was quickly adopted by RAF Coastal Command
RAF Coastal Command was a formation within the Royal Air Force (RAF). It was founded in 1936, when the RAF was restructured into Fighter, Bomber and Coastal Commands and played an important role during the Second World War. Maritime Aviation ...
, who needed a longer-range system than Gee offered. To keep their use less obvious, all British records refer to the system as "Consol".
Coastal Command's use became so widespread that they became completely dependent on the system. Late in the war, when the Germans lost access to Spain, a lack of parts led to one of the Spanish stations going offline. Edward Fennessy arranged a supply of spare parts provided by the RAF to keep it operational.
Postwar use
Sonne, now known by its UK code name Consol, was widely used in the post-war era. Compared to systems like VOR
VOR or vor may refer to:
Organizations
* Vale of Rheidol Railway in Wales
* Voice of Russia, a radio broadcaster
* Volvo Ocean Race, a yacht race
Science, technology and medicine
* VHF omnidirectional range, a radio navigation aid used in a ...
or RDF, Consol required nothing more in the navigating vessel than a conventional radio and the ability to count. This proved so attractive that new Consol stations were set up in France, Northern Ireland, and even three in the US (where it was known as Consolan) and several in the USSR. It was one of the ICAO's recommended long-range navigation systems.
Although more accurate and easier to use systems were introduced, notably LORAN-C
Loran-C is a hyperbolic radio navigation system that allows a receiver to determine its position by listening to low frequency radio signals that are transmitted by fixed land-based radio beacons. Loran-C combined two different techniques to ...
, Consol's low cost of implementation (a radio) kept it in use as a pleasure boating system for many years. Most Consol broadcasters remained in use until the 1980s, with the Stavanger station remaining online until 1991. By this point LORAN and GPS systems were falling in cost, and these had replaced most forms of radio navigation by 2000.
List of Consol stations
* Ploneis, France , call sign TRQ later FRQ, frequency 257 kHz
* Andøya
Andøya is the northernmost island in the Vesterålen archipelago, situated about inside the Arctic circle. Andøya is located in Andøy Municipality in Nordland county, Norway. The main population centres on the island include the villages of ...
, Norway , call sign LEX, frequency 332.5 kHz
* Bjørnøya, Norway , call sign LJS, frequency 332.5 kHz
* Stavanger- Varhaug, Norway , call sign LEC, frequency 319 kHz
* Lugo- Outeiro de Rei, Galicia, Spain , call sign LG, frequency 303 then 285 kHz
* Sevilla
Seville (; es, Sevilla, ) is the capital and largest city of the Spanish autonomous community of Andalusia and the province of Seville. It is situated on the lower reaches of the River Guadalquivir, in the southwest of the Iberian Peninsula ...
, Spain , call sign SL, frequency 311 then 315 kHz
* Jan Mayen Island
Jan Mayen () is a Norwegian volcanic island in the Arctic Ocean with no permanent population. It is long (southwest-northeast) and in area, partly covered by glaciers (an area of around the Beerenberg volcano). It has two parts: larger n ...
, Svalbard and Jan Mayen , call sign LMC, frequency 332.5 kHz
* Bushmills
Bushmills (From Irish ''Muileann na Buaise'') is a village on the north coast of County Antrim, Northern Ireland. Bushmills had a population of 1,295 in the 2011 Census. This article contains quotations from this source, which is available und ...
, Northern Ireland, UK , call sign MWN, frequency 263 then 266 kHz
* Miami, FL
Miami ( ), officially the City of Miami, known as "the 305", "The Magic City", and "Gateway to the Americas", is a coastal metropolis and the county seat of Miami-Dade County in South Florida, United States. With a population of 442,241 at the ...
, USA , call sign MMF, frequency 190 kHz
* Nantucket, MA
Nantucket () is an island about south from Cape Cod. Together with the small islands of Tuckernuck and Muskeget, it constitutes the Town and County of Nantucket, a combined county/town government that is part of the U.S. state of Massachuse ...
, USA , call sign TUK, frequency 194 kHz
* San Francisco, CA
San Francisco (; Spanish for " Saint Francis"), officially the City and County of San Francisco, is the commercial, financial, and cultural center of Northern California. The city proper is the fourth most populous in California and 17th ...
, USA , call sign SFI, frequency 192 kHz
* Kanin Nos, Russian SFSR, USSR , call sign KN, frequency 269 kHz
* Ostrov Pankrat'yeva, Russian SFSR, USSR , call sign PA, frequency 280 kHz
* Rybachi, Russian SFSR, USSR , call sign RB, frequency 363 kHz
Andøya, Bjørnøya and Jan Mayen Island shared the same frequency. They took turns broadcasting over a 4 minute cycle.
Proposed Consol stations never built
* Cape Harrison, NL, Canada
* St. John's, NL, Canada
* Nanortalik
Nanortalik (), formerly Nennortalik, is a town in Nanortalik Island, Kujalleq municipality, southern Greenland. With 1,185 inhabitants as of 2020, it is the eleventh-largest town in the country. The name ''Nanortalik'' means "Place of Polar Bear ...
, Greenland
* Eyrarbakki
Eyrarbakki () is a fishing village on the south coast of Iceland with a population of about 570 people, not including inhabitants of the prison located there. The village is founded on the Great Þjórsá Lava.
History
For centuries, the harbou ...
, Iceland
* Santa Maria, Azores, Portugal , call sign SMA, frequency 323 kHz (repurposed homing beacon)
* Atlantic City, NJ
Atlantic City, often known by its initials A.C., is a coastal resort city in Atlantic County, New Jersey, United States. The city is known for its casinos, boardwalk, and beaches. In 2020, the city had a population of 38,497. , USA, call sign ATA, test frequency 526 kHz (built but shutdown due to frequency assignment issues)
* Cape Hatteras, NC, USA, frequency 198 kHz
* Pescadero, CA, USA, call sign PES, frequency 190 kHz (first built as a homing beacon, but was never converted to a Consol station as planned)
* Point Conception, CA, USA
References
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Radio navigation