The Allouis longwave transmitter has been
France
France, officially the French Republic, is a country located primarily in Western Europe. Overseas France, Its overseas regions and territories include French Guiana in South America, Saint Pierre and Miquelon in the Atlantic Ocean#North Atlan ...
's central
longwave
In radio, longwave (also spelled long wave or long-wave and commonly abbreviated LW) is the part of the radio spectrum with wavelengths longer than what was originally called the medium-wave (MW) broadcasting band. The term is historic, dati ...
broadcast
Broadcasting is the data distribution, distribution of sound, audio audiovisual content to dispersed audiences via a electronic medium (communication), mass communications medium, typically one using the electromagnetic spectrum (radio waves), ...
transmitter
In electronics and telecommunications, a radio transmitter or just transmitter (often abbreviated as XMTR or TX in technical documents) is an electronic device which produces radio waves with an antenna (radio), antenna with the purpose of sig ...
since 1939. It is located near the village of
Allouis.
It broadcast the
France Inter public radio station from October 1952
[ until 31 December 2016. Since 2017, it broadcasts only the TDF time signal, which has been renamed ALS162 since 2017.
The first transmitter, built in 1939 during the Phoney War, used an aerial with four masts and a transmitter rated at 500 ]kilowatt
The watt (symbol: W) is the unit of Power (physics), power or radiant flux in the International System of Units (SI), equal to 1 joule per second or 1 kg⋅m2⋅s−3. It is used to quantification (science), quantify the rate of Work ...
s.[Chronologie des radios françaises en ondes longues 1921–2000]
("Chronology of french long-wave transmitters 1921–2000") It was destroyed in 1944 during the scorched earth
A scorched-earth policy is a military strategy of destroying everything that allows an enemy military force to be able to fight a war, including the deprivation and destruction of water, food, humans, animals, plants and any kind of tools and i ...
retreat by German forces.
On 19 October 1952 a new 250 kW transmitter came into service. This used a special cage aerial, mounted on a high earthed mast. In 1957 the transmission power was increased to 600 kW, in 1974 to 1,000 kW, and in 1981 to 2,000 kW. Transmission power was reduced to 1,000 kW during the hours of darkness. In 2011 the transmission power was reduced to 1,500 kW for cost savings. For the same reason the transmission power was reduced to 1,100 kW in 2017 and subsequently in February 2020 to 800 kW.[ANFR website (in French)]
/ref> In 2024, tests were performed at a reduced transmission power of 675 kW.
In 1974 the aerial was renewed. The cage aerials were removed and the mast height was increased to . A second mast of the same height was constructed at the same time.
In 1977, the current phase modulated time signal was added to the transmissions. The broadcast frequency, formerly 164 kHz, was changed to 163.840 kHz (the 5th harmonic of the common 32,768 Hz timekeeping frequency used by most quartz clocks) to be a more convenient frequency standard.[
In 1980, the first ]atomic clock
An atomic clock is a clock that measures time by monitoring the resonant frequency of atoms. It is based on atoms having different energy levels. Electron states in an atom are associated with different energy levels, and in transitions betwee ...
was installed to regulate the carrier frequency
In telecommunications, a carrier wave, carrier signal, or just carrier, is a periodic waveform (usually sinusoidal) that conveys information through a process called ''modulation''. One or more of the wave's properties, such as amplitude or fre ...
.[Les ré-orientations]
/ref>
On 1 February 1986, the frequency was changed to its current value of 162 kHz (still an accurately controlled frequency standard) to bring it to a multiple of 9 kHz in accordance with the Geneva Frequency Plan of 1975.
The radio channel France Inter announced during 2016 that the channel would discontinue transmitting on the 162 kHz frequency on 31 December 2016, seeking cost savings of approximately 6 million Euros per year. The transmission of the ALS162 time signal was and will be continued after this date, as this time signal is critical for over 300,000 devices, which are deployed within French enterprises and state entities, like the French railways SNCF, the electricity distributor ENEDIS, airports, hospitals, municipalities, et cetera.
The transmitter is owned by TéléDiffusion de France and the dissemination of the Metropolitan French national legal time to the public is a joint responsibility of ANFR (state body for radio frequencies), the trade body France Horlogerie and the LNE-SYRTE and LNE-LTFB time laboratories.Provision of the legal time by ALS162 signal
/ref>
References
External links
*
* http://perso.wanadoo.fr/tvignaud/am/allouis/fr-allouis.htm
* http://www.skyscraperpage.com/diagrams/?b44247
* http://skyscraperpage.com/diagrams/?b58020
{{Time measurement and standards
Radio masts and towers in Europe
Buildings and structures in Cher (department)
Transmitter sites in France
Time signal radio stations
1939 establishments in France