The Sainte-Assise transmitter (french: Émetteur de Sainte-Assise) is a

very low frequency Very low frequency or VLF is the ITU designation for radio frequencies (RF) in the range of 3–30 kHz, corresponding to wavelengths from 100 to 10 km, respectively. The band is also known as the myriameter band or myriameter wave a ...

(VLF) radio

transmitter In electronics and telecommunications, a radio transmitter or just transmitter is an electronic device which produces radio waves with an antenna. The transmitter itself generates a radio frequency alternating current, which is applied to the ...

and military installation located on the grounds of the in the

communes An intentional community is a voluntary residential community which is designed to have a high degree of social cohesion and teamwork from the start. The members of an intentional community typically hold a common social, political, relig ...

of Seine-Port, Boissise-la-Bertrand, and

Cesson Cesson () is a Communes of France, commune in the Seine-et-Marne Departments of France, department in the Île-de-France Regions of France, region in north-central France. Demographics The inhabitants are called ''Cessonnais''. See also *Commun ...

in the

Seine-et-Marne Seine-et-Marne () is a department in the Île-de-France region in Northern France. Named after the rivers Seine and Marne, it is the region's largest department with an area of 5,915 square kilometres (2,284 square miles); it roughly covers its ...

department of the

Île-de-France The Île-de-France (, ; literally "Isle of France") is the most populous of the eighteen regions of France. Centred on the capital Paris, it is located in the north-central part of the country and often called the ''Région parisienne'' (; en, Pa ...

region In geography, regions, otherwise referred to as zones, lands or territories, are areas that are broadly divided by physical characteristics ( physical geography), human impact characteristics ( human geography), and the interaction of humanity an ...

France France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of overseas regions and territories in the Americas and the Atlantic, Pacific and Indian Oceans. Its metropolitan area ...

. The transmitter's original equipment was inaugurated on 9 January 1921, at the time being the most powerful radio transmitter on Earth. On 26 November 1921 the first French

radio program A radio program, radio programme, or radio show is a segment of content intended for broadcast on radio. It may be a one-time production or part of a periodically recurring series. A single program in a series is called an episode. Radio networ ...

was transmitted from Sainte-Assise. In 1965 the transmitter was used to send VLF signals to FR-1, the first French

satellite A satellite or artificial satellite is an object intentionally placed into orbit in outer space. Except for passive satellites, most satellites have an electricity generation system for equipment on board, such as solar panels or radioi ...

. Since 1998 the

French Navy The French Navy (french: Marine nationale, lit=National Navy), informally , is the maritime arm of the French Armed Forces and one of the five military service branches of France. It is among the largest and most powerful naval forces in t ...

has used the transmitter to communicate with submerged submarines.

Design

Large spiral inductors in radio transmitter - France 1922

The original equipment of the Saint-Assise transmitter included large spiral "pancake"

inductor An inductor, also called a coil, choke, or reactor, is a passive two-terminal electrical component that stores energy in a magnetic field when electric current flows through it. An inductor typically consists of an insulated wire wound into a c ...

s in a high-power

longwave In radio, longwave, long wave or long-wave, and commonly abbreviated LW, refers to parts of the radio spectrum with wavelengths longer than what was originally called the medium-wave broadcasting band. The term is historic, dating from the e ...

alternator An alternator is an electrical generator that converts mechanical energy to electrical energy in the form of alternating current. For reasons of cost and simplicity, most alternators use a rotating magnetic field with a stationary armature.Gor ...

transmitter which served as a transatlantic

wireless telegraphy Wireless telegraphy or radiotelegraphy is transmission of text messages by radio waves, analogous to electrical telegraphy using cables. Before about 1910, the term ''wireless telegraphy'' was also used for other experimental technologies for ...

station. These combinations of inductors and alternator transmitters were called " oscillation transformers." The primary coil was connected to a large rotating radio frequency alternator which produced the radio signal. The secondary coil was connected to the overhead wire aerial system, over long, supported on sixteen high towers, which radiated the radio waves. The inductance of the secondary coil resonated with the

capacitance Capacitance is the capability of a material object or device to store electric charge. It is measured by the change in charge in response to a difference in electric potential, expressed as the ratio of those quantities. Commonly recognized ar ...

of the antenna to form the

tank circuit An LC circuit, also called a resonant circuit, tank circuit, or tuned circuit, is an electric circuit consisting of an inductor, represented by the letter L, and a capacitor, represented by the letter C, connected together. The circuit can a ...

of the transmitter in order to control the output frequency. It transmitted on a wavelength of , or 21 kHz. The station had two 500 kW Alexanderson alternator transmitters and two 250 kW alternator transmitters. The station's transmitters were designed to handle

telegram Telegraphy is the long-distance transmission of messages where the sender uses symbolic codes, known to the recipient, rather than a physical exchange of an object bearing the message. Thus flag semaphore is a method of telegraphy, whereas ...

traffic at a rate of 100

words per minute Words per minute, commonly abbreviated wpm (sometimes uppercased WPM), is a measure of words processed in a minute, often used as a measurement of the speed of typing, reading or Morse code sending and receiving. Alphanumeric entry Since word ...

, and all six of them had a combined capacity of 36,000 words per hour. The spiral shape of the coils reduced resistive losses at radio frequency due to

proximity effect Proximity effect may refer to: * Proximity effect (atomic physics) * Proximity effect (audio), an increase in bass or low frequency response when a sound source is close to a microphone * ''Proximity Effect'' (comics), a comic book series written by ...

. The copper conductors are made in the form of wide strips to increase their surface area in order to reduce their resistance at radio frequencies, since radio frequency currents flow along the surface of conductors due to skin effect.

History

The , a subsidiary of

Compagnie générale de la télégraphie sans fil The Compagnie générale de la télégraphie sans fil (CSF: General Wireless Telegraphy Company) was a French company founded in 1918 during a reorganization and expansion of the Société française radio-électrique (SFR), which became a subsidia ...

(CSF), built the Saint-Assise transmitter. The first antenna at Saint-Assise was supported by eleven pylons and five masts. When it opened on 9 January 1921, the transmitter was the most powerful on

Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...

, capable of broadcasting to the entire planet. On 26 November 1921 the first experimental French

was transmitted from Sainte-Assise using a 1 kW-long wave transmitter. As part of the broadcast, opera singer

Yvonne Brothier Yvonne Brothier (born 6 June 1889 in Saint-Julien-l'Ars, Vienne, died in Paris, 22 January 1967) was a soprano operatic singer who worked principally at the Opéra-Comique, Paris. After singing in Brussels in 1914, she made her début at the ...

performed

La Marseillaise "La Marseillaise" is the national anthem of France. The song was written in 1792 by Claude Joseph Rouget de Lisle in Strasbourg after the declaration of war by France against Austria, and was originally titled "Chant de guerre pour l'Armée du R ...

, a song from ''

Mireille Mireille () is a French given name, derived from the Provençal Occitan name ''Mirèio'' (or ''Mirèlha'' in the classical norm of Occitan, ). It could be related to the Occitan verb ''mirar'' "to look, to admire" or to the given names ''Miriam'' ...

'', and an

aria In music, an aria ( Italian: ; plural: ''arie'' , or ''arias'' in common usage, diminutive form arietta , plural ariette, or in English simply air) is a self-contained piece for one voice, with or without instrumental or orchestral accompa ...

from ''

The Barber of Seville ''The Barber of Seville, or The Useless Precaution'' ( it, Il barbiere di Siviglia, ossia L'inutile precauzione ) is an ''opera buffa'' in two acts composed by Gioachino Rossini with an Italian libretto by Cesare Sterbini. The libretto was based ...

''. Subsequently, the site was a center of early French experiments with television. In 1941, 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 ...

, the Kriegsmarine requisitioned Sainte-Assise to allow communications between

Berlin Berlin ( , ) is the capital and List of cities in Germany by population, largest city of Germany by both area and population. Its 3.7 million inhabitants make it the European Union's List of cities in the European Union by population within ci ...

and

U-boat U-boats were naval submarines operated by Germany, particularly in the First and Second World Wars. Although at times they were efficient fleet weapons against enemy naval warships, they were most effectively used in an economic warfare ro ...

s. Despite this, Sainte-Assise was not targeted or damaged by Allied bombing and all of the antennas survived the war. The Saint-Assise transmitter played a key role in the 1965 launch of FR-1, the first French satellite. FR-1's mission objective was to study the composition and structure of the ionosphere,

plasmasphere The plasmasphere, or inner magnetosphere, is a region of the Earth's magnetosphere consisting of low-energy (cool) plasma. It is located above the ionosphere. The outer boundary of the plasmasphere is known as the plasmapause, which is defined ...

, and magnetosphere by measuring the propagation of VLF waves and the local electron density of plasma in those atmospheric layers. For the VLF wave experiments, the Sainte-Assise transmitter and another ground station in Balboa,

Panama Panama ( , ; es, link=no, Panamá ), officially the Republic of Panama ( es, República de Panamá), is a transcontinental country spanning the southern part of North America and the northern part of South America. It is bordered by Co ...

, transmitted signals at 16.8 kHz and 24 kHz, respectively, while the satellite's magnetic and electric sensors orbiting about away analyzed the magnetic field of the received wave. In 1991 part of the station was sold by France Télécom to the

, to become the Sainte-Assise Marine Communications Center (french: Centre de transmissions marine; CTM). The CTM, inaugurated in 1998, is tasked with communicating with submerged submarines. An entire company of Fusiliers marins patrols the grounds. In December 2000 three unused 180-meter pylons were dismantled.

Globecast Globecast is a service company for the radio, television and media industry, providing solutions for media and content management, aggregation, formatting, processing, transmission and distribution. These contents are feeding various television a ...

, an

Orange S.A. Orange S.A. (), formerly France Télécom S.A. (stylized as france telecom) is a French multinational telecommunications corporation. It has 266 million customers worldwide and employs 89,000 people in France, and 59,000 elsewhere. In 2015, ...

subsidiary, owns and operates the Sainte-Assise teleport (located on a second site near the Saint-Assise transmitter) which supports multiple parabolic satellite dishes measuring between and in diameter. This station ensures the transmission of up-link signals to

communications satellite A communications satellite is an artificial satellite that relays and amplifies radio telecommunication signals via a transponder; it creates a communication channel between a source transmitter and a receiver at different locations on Earth ...

s, in particular video and audio signals for the direct broadcasting of satellite radio and

television Television, sometimes shortened to TV, is a telecommunication medium for transmitting moving images and sound. The term can refer to a television set, or the medium of television transmission. Television is a mass medium for advertisin ...

References

{{DEFAULTSORT:Sainte-Assise transmitter Towers completed in 1921 Radio masts and towers in Europe Towers in France Transmitter sites in France Buildings and structures in Île-de-France French Navy technology 1921 establishments in France