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Encyclopedia > Low frequency
low frequency (LF)
Cycles per second: 30 kHz to 300 kHz

Wavelength: 10 km to 1 km

Low Frequency or LF refers to Radio Frequencies (RF) in the range of 30–300 kHz. In Europe, part of the LF spectrum is used for AM broadcast service. In the western hemisphere, its main use is for aircraft beacon, navigation (LORAN), information, and weather systems. Time signal stations MSF, DCF77, JJY and WWVB are found in this band. Rough plot of Earths atmospheric transmittance (or opacity) to various wavelengths of electromagnetic radiation, including radio waves. ... Longwave can also refer to the economics concept of Kondratiev waves, or to the rock band Longwave The Longwave radio broadcasting band is the range of frequencies between 148. ... LORAN (LOng RAnge Navigation) is a terrestrial navigation system using low frequency radio transmitters that use the time interval between radio signals received from three or more stations to determine the position of a ship or aircraft. ... The MSF time signal is a broadcast from the VLF transmitter Rugby near Rugby, Warwickshire based on time standards maintained by the British National Physical Laboratory. ... DCF77 is a longwave time signal radio station. ... JJY is the callsign of a longwave time signal radio station similar to WWVB. The station is located in Japan, operated by a branch of the Japanese government known as the National Institute of Information and Communications Technology. ... WWVB is a special NIST time signal radio station in Fort Collins, Colorado, co-located with WWV. WWVB is the station that radio-controlled clocks throughout North America use to synchronize themselves. ...

Contents

Standard time signals

In the frequency range 40-80 kHz, there are several standard time and frequency stations, such as

  • JJY in Japan (40 and 60 kHz)
  • MSF in Rugby, England (60 kHz)
  • WWVB in Colorado, USA (60 kHz)
  • HBG in Prangins, Switzerland (75 kHz)
  • DCF77 near Frankfurt am Main, Germany (77.5 kHz)

In Europe and Japan, many low-cost consumer devices have since the late 1980s contained radio clocks with an LF receiver for these signals. Since these frequencies propagate by ground wave only, the precision of time signals is not affected by varying propagation paths between the transmitter, the ionosphere, and the receiver. In the United States, such devices became feasible for the mass market only after the output power of WWVB was increased in 1997 and 1999. JJY is the callsign of a longwave time signal radio station similar to WWVB. The station is located in Japan, operated by a branch of the Japanese government known as the National Institute of Information and Communications Technology. ... The MSF time signal is a broadcast from the VLF transmitter Rugby near Rugby, Warwickshire based on time standards maintained by the British National Physical Laboratory. ... WWVB is a special NIST time signal radio station in Fort Collins, Colorado, co-located with WWV. WWVB is the station that radio-controlled clocks throughout North America use to synchronize themselves. ... DCF77 is a longwave time signal radio station. ... A radio clock A radio clock is a clock that is synchronized by a time code bit stream transmitted by a radio transmitter connected to a time standard such as an atomic clock. ... Ground wave: In radio transmission, a surface wave that propagates close to the surface of the Earth. ... WWVB is a special NIST time signal radio station in Fort Collins, Colorado, co-located with WWV. WWVB is the station that radio-controlled clocks throughout North America use to synchronize themselves. ... 1997 (MCMXCVII) was a common year starting on Wednesday of the Gregorian calendar. ... 1999 (MCMXCIX) was a common year starting on Friday, and was designated the International Year of Older Persons by the United Nations. ...


Military

Radio signals below 50 kHz are capable of penetrating ocean depths to approximately 200 meters, the longer the wavelength, the deeper. The British, German, Indian, Russian, Swedish, United States and probably more navies communicate with submarines on these frequencies. The multinational Combined Task Force One Five Zero (CTF-150) The British Grand Fleet, the supreme naval force of World War I A rare occurrence of a 5-country multinational fleet, during Operation Enduring Freedom in the Oman Sea. ... German UC-1 class World War I submarine A model of Günther Priens Unterseeboot 47 (U-47), German WWII Type VII diesel-electric hunter Typhoon class nuclear ballistic missile submarine USS Virginia, a Virginia-class nuclear attack (SSN) submarine A submarine is a specialized watercraft that can operate...


In addition, Royal Navy nuclear submarines carrying ballistic missiles are allegedly under standing orders to monitor the BBC Radio 4 transmission on 198 kHz in waters near the UK. It is rumoured that they are to construe a sudden halt in transmission, particularly of the morning news programme Today, as an indicator that the UK is under attack, whereafter their sealed orders take effect. The Royal Navy of the United Kingdom is the oldest of the British armed services (and is therefore the Senior Service). ... BBC Radio 4 is a British domestic radio station which broadcasts a wide variety of chiefly spoken-word programmes including news, drama, comedy, science and history. ... Today, sometimes referred to as the Today programme to avoid ambiguity, is BBC Radio 4s long-running early morning news and current affairs programme, which is now broadcast from 6am to 9am from Monday to Friday and from 7am to 9am on Saturdays. ...

For more details on this topic, see Communication with submarines.

Because electromagnetic radiation such as normal radio communication cannot travel through thick conductors such as salt water, communication with submarines when they are submerged is a difficult technological task which requires specific techniques and devices. ...

Experimental and amateur

A 2.1 kHz allocation, the 136 kHz band (135.7 to 137.8 kHz), is available to amateur radio operators in some countries in Europe, New Zealand and French overseas dependencies. The world record distance for a two-way contact is over 10,000 km from near Vladivostok to New Zealand. [1]. As well as conventional morse code many operators use very slow computer controlled morse code or specialised digital communications modes. A proposal at the WRC-07 World Radiocommunication Conference aims to make this a worldwide amateur radio allocation. The 136 kHz band is the lowest frequency band in which amateur radio operators are allowed to transmit. ... Ham radio station with modern solid-state transceiver featuring LCD display and DSP capabilities Ham radio station with vintage vacuum tube gear featuring separate transmitter, receiver and power supply Amateur radio, often called Ham radio, is a hobby and public service enjoyed by about 6 million people throughout the world. ... Vladivostok (Russian: ) is the administrative center of Primorsky Krai, Russia, situated close to the Russo-Sino border and North Korea. ... 1922 Chart of the Morse Code Letters and Numerals Morse code is a method for transmitting information by using standardized sequences of variously spaced short and long elements for the characters and words in a message. ... World Radiocommunication Conference (WRC) is organized by ITU to review, and, if necessary, revise the Radio Regulations, the international treaty governing the use of the radio-frequency spectrum and the geostationary-satellite and non-geostationary-satellite orbits. ...


The UK allocated a 2.8 kHz sliver of spectrum from 71.6 to 74.4 kHz beginning in April 1996 to UK amateurs who applied for a Notice of Variation to use the band on a noninterference basis with a maximum output power of 1 W ERP (effective radiated power). This was withdrawn on 30 June 2003 after a number of extensions in favour of the European-harmonised 136 kHz band. [2] A 1-watt transmission of very slow Morse Code between G3AQC (in the UK) and W1TAG (in the USA) spanned the Atlantic Ocean for 3275 miles on November 21-22, 2001.


In the United States there is a special licence free allocation in the longwave range called LowFER. This experimental allocation between 160 and 190 kHz is sometimes called the "Lost Band". Unlicensed operation by the public is permitted south of 60 degrees north latitude, except where interference would occur to 10 licensed location service stations located along the coasts. Regulations for use include a power output of no more than 1 watt, and an antenna/ground-lead length of no more than 15 meters, and a field strength of no more than 4.9 microvolts/meter. Also, emissions outside of the 160–190 kHz band must be attenuated by at least 20 dB below the level of the unmodulated carrier. Many experimenters in this band are amateur radio operators. LowFER (Low-Frequency Experimental Radio) is a license-free form of amateur radio practicised in the United States and Canada on frequencies between 160 kHz and 190 kHz. ...


Antennas

Antennas used at these low frequencies are usually mast radiators, which are fed at the bottom and which are insulated from ground, or mast antennas fed by the guy ropes (such masts are usually grounded), T-aerials, L-aerials and long wire aerials. A typical mast radiator Base feed: mast is fed from Aerial Tuning Unit on right via conductor to top of brown ceramic insulator. ...


The height of aerials differ by usage. For NDB's the height is just around 10 metres, while for more powerful navigation transmitters such as DECCA, masts with a height around 100 metres are used. T-aerials have a height between 50 and 200 metres, while mast aerials are usually taller than 150 metres. Decca may refer to: Decca Records, a 1929 British record label, also known as Decca Music Group Decca Radar (later Racal-Decca Marine), a British marine electronics manufacturer, a spin-off from the gramophone and records company Decca tree, a microphone recording system London Decca, a maker of turntable tonearms...


The height of mast aerials for LORAN-C is around 190 metres for transmitters with radiated power below 500 kW, and around 400 metres for transmitters greater than 1,000 kilowatts. The main type of LORAN-C aerial is insulated from ground. LORAN (LOng RAnge Navigation) is a terrestrial navigation system using low frequency radio transmitters. ...


Longwave broadcasting stations use mast antennas with heights of more than 150 metres or T-aerials. The mast antennas can be ground-fed insulated masts or upper-fed grounded masts. It is also possible to use cage aerials on grounded masts.


Nearly all longwave aerials are not as high as one quarter of the radiated wavelength. The only longwave transmission aerial realized with a height corresponding to a half radiated wavelength was Warsaw Radio Mast. The Warsaw radio mast in Konstantynów The Warsaw radio mast a few months after collapse Warsaw Radio Mast from far away The Warsaw radio mast was the tallest structure ever built; however, it existed only from 1973 to 1991. ...


For broadcasting stations often directional aerials are required. They consist of multiple masts, which often have the same height. Some longwave aerials consist of multiple mast antennas arranged in a circle with or without a mast antenna in the centre. Such aerials focus the transmitted power toward ground and gave a large zone of fade-free reception. This aerial type is rarely used, because they are very expensive and require much space and because fading occurs on longwave much more rarely than in the medium wave range. One aerial of this kind was used by transmitter Orlunda in Sweden. The Longwave transmitter Orlunda was a broadcast transmission facility for longwave at Orlunda, Sweden near Motala, which was established in 1962. ...


Longwave transmitting antennas for high power transmitters require large amounts of space, and have been the cause of controversy in the United States and Europe due to concerns about possible health hazards associated with exposure to high-power radio waves.


Radio spectrum
ELF SLF ULF VLF LF MF HF VHF UHF SHF EHF
3 Hz 30 Hz 300 Hz 3 kHz 30 kHz 300 kHz 3 MHz 30 MHz 300 MHz 3 GHz 30 GHz
30 Hz 300 Hz 3 kHz 30 kHz 300 kHz 3 MHz 30 MHz 300 MHz 3 GHz 30 GHz 300 GHz


Radio frequency, or RF, refers to that portion of the electromagnetic spectrum in which electromagnetic waves can be generated by alternating current fed to an antenna. ... Extremely low frequency (ELF) is the band of radio frequencies from 3 to 30 Hz. ... Super Low Frequency (SLF) is the frequency range between 30 hertz and 300 hertz. ... Ultra Low Frequency (ULF) is the frequency range between 300 hertz and 3000 hertz. ... Very low frequency or VLF refers to radio frequencies (RF) in the range of 3 to 30 kHz. ... Mediumwave radio transmissions (sometimes called Medium frequency or MF) are those between the frequencies of 300 kHz and 3000 kHz. ... High frequency (HF) radio frequencies are between 3 and 30 MHz. ... Very high frequency (VHF) is the radio frequency range from 30 MHz (wavelength 10 m) to 300 MHz (wavelength 1 m). ... This article is about the radio frequency. ... Microwave Slang for small waves, like at a beach, often used by surfers. ... Extremely high frequency is the highest radio frequency band. ...



v  d  e
The Electromagnetic Spectrum
(Sorted by wavelength, short to long)
Gamma rayX-rayUltravioletVisible spectrumInfraredTerahertz radiationMicrowaveRadio waves
Visible (optical) spectrum: VioletBlueGreenYellowOrangeRed
Microwave spectrum: W bandV bandK band: Ka band, Ku bandX bandC bandS bandL band
Radio spectrum: EHFSHFUHFVHF • HF • MFLFVLFULFSLFELF
Wavelength designations: MicrowaveShortwaveMediumwaveLongwave

Legend: γ = Gamma rays HX = Hard X-rays SX = Soft X-Rays EUV = Extreme ultraviolet NUV = Near ultraviolet Visible light NIR = Near infrared MIR = Moderate infrared FIR = Far infrared Radio waves: EHF = Extremely high frequency (Microwaves) SHF = Super high frequency (Microwaves) UHF = Ultra high frequency VHF = Very high frequency HF = High... This article is about electromagnetic radiation. ... In the NATO phonetic alphabet, X-ray represents the letter X. An X-ray picture (radiograph) taken by Röntgen An X-ray is a form of electromagnetic radiation with a wavelength approximately in the range of 5 pm to 10 nanometers (corresponding to frequencies in the range 30 PHz... The solar corona as seen in deep ultraviolet light at 17. ... The visible spectrum (or sometimes optical spectrum) is the portion of the electromagnetic spectrum that is visible to (can be detected by) the human eye. ... Image of two girls in mid-infrared (thermal) light (false color) Infrared (IR) radiation is electromagnetic radiation of a wavelength longer than that of visible light, but shorter than that of radio waves. ... Radio waves sent at terahertz frequencies, known as terahertz radiation, terahertz waves, T-rays, T-light, T-lux and THz, are in the region of the light spectrum between 300 gigahertz (3x1011 Hz) and 3 terahertz (3x1012 Hz), corresponding to the wavelength range starting at submillimeter (<1 millimeter) and 100... Microwaves are electromagnetic waves with wavelengths longer than those of terahertz (THz) frequencies, but relatively short for radio waves. ... Rough plot of Earths atmospheric transmittance (or opacity) to various wavelengths of electromagnetic radiation, including radio waves. ... The visible spectrum (or sometimes optical spectrum) is the portion of the electromagnetic spectrum that is visible to (can be detected by) the human eye. ... Violet (named after the flower violet) is used in two senses: first, referring to the color of light at the short-wavelength end of the visible spectrum, approximately 380–420 nanometres (this is a spectral color). ... The term blue may refer any of a number of similar colours. ... Mossy, green fountain in Wattens, Austria. ... Rubber duckies. ... The colour orange occurs between red and yellow in the visible spectrum at a wavelength of about 585–620 nanometres. ... Red may be any of a number of similar colours at the lowest frequencies of light discernible by the human eye. ... Microwaves are electromagnetic waves with wavelengths longer than those of terahertz (THz) frequencies, but relatively short for radio waves. ... The W band of the microwave part of the electromagnetic spectrum and ranges from 75 to 111 GHz. ... The V band (vee-band) of the electromagnetic spectrum ranges from 50 to 75 GHz. ... K band is a portion of the electromagnetic spectrum in the microwave range of frequencies ranging between 12 to 63 GHz. ... The Ka band (kurz-above band) is a portion of the K band of the microwave band of the electromagnetic spectrum. ... The Ku band (kay-yoo kurz-under band) is a portion of the electromagnetic spectrum in the microwave range of frequencies ranging from 11 to 18 GHz. ... The X band (3-cm radar spot-band) of the microwave band of the electromagnetic spectrum roughly ranges from 5. ... C band (compromise band) is a portion of electromagnetic spectrum in the microwave range of frequencies ranging from 4 to 6 GHz. ... The S band ranges from 2. ... L band (20-cm radar long-band) is a portion of the microwave band of the electromagnetic spectrum ranging roughly from 0. ... Radio frequency, or RF, refers to that portion of the electromagnetic spectrum in which electromagnetic waves can be generated by alternating current fed to an antenna. ... Extremely high frequency is the highest radio frequency band. ... Microwave Slang for small waves, like at a beach, often used by surfers. ... This article is about the radio frequency. ... Very high frequency (VHF) is the radio frequency range from 30 MHz (wavelength 10 m) to 300 MHz (wavelength 1 m). ... High frequency (HF) radio frequencies are between 3 and 30 MHz. ... Mediumwave radio transmissions (sometimes called Medium frequency or MF) are those between the frequencies of 300 kHz and 3000 kHz. ... Very low frequency or VLF refers to radio frequencies (RF) in the range of 3 to 30 kHz. ... Ultra Low Frequency (ULF) is the frequency range between 300 hertz and 3000 hertz. ... Super Low Frequency (SLF) is the frequency range between 30 hertz and 300 hertz. ... Extremely low frequency (ELF) is the band of radio frequencies from 3 to 30 Hz. ... The wavelength is the distance between repeating units of a wave pattern. ... Microwaves are electromagnetic waves with wavelengths longer than those of terahertz (THz) frequencies, but relatively short for radio waves. ... Shortwave radio redirects here. ... Mediumwave radio transmissions serves as the most common band for broadcasting. ... Longwave can also refer to the economics concept of Kondratiev waves, or to the rock band Longwave The Longwave radio broadcasting band is the range of frequencies between 148. ...

References

  1. ^ QSO ZL / UA0 on 136 kHz. The World of LF.
  2. ^ UK Spectrum Strategy 2002. Ofcom.

// Ofcom was designed to be a super regulator, required in an age where many media platforms are converging. ...

See also

Longwave can also refer to the economics concept of Kondratiev waves, or to the rock band Longwave The Longwave radio broadcasting band is the range of frequencies between 148. ... WGU-20, also known as the last radio station, was a unique radio station was operated by the Defense Civil Preparedness Agency (now the Federal Emergency Management Agency) in the mid to late 1970s. ...

External articles

  • Tomislav Stimac, "Definition of frequency bands (VLF, ELF... etc.)". IK1QFK Home Page (vlf.it).

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