Misplaced Pages

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68-407: AN/URC-117 was the system's Joint Electronics Type Designation System identifier, which signified various radio components installed in different locations. Each GWEN Relay Node site featured a longwave transmitting tower, generally between 290 and 299 feet (88 and 91 m) tall, and emitting an RF output of between 2,000 and 3,000 watts . Of 240 planned GWEN towers, only 58 were built. In 1994,

136-563: A skywave . The medium-wave transmitter at Berlin-Britz for transmitting RIAS used a cross dipole mounted on five 30.5-metre-high guyed masts to transmit the skywave to the ionosphere at nighttime. Because at these frequencies atmospheric noise is far above the receiver signal-to-noise ratio , inefficient antennas much smaller than a wavelength can be used for receiving. For reception at frequencies below 1.6 MHz, which includes long and medium waves, loop antennas are popular because of their ability to reject locally generated noise. By far

204-422: A (V) signifier. The (V) signifier would be warranted if the item accepted variable configurations of a particular component. For example: A suffix of "(P)" following the type designation number and any modification letters indicates a Unit which is designed to accept "plug-in" modules capable of changing the function, frequency, or other technical characteristics of the unit. The plug-in is not considered part of

272-708: A defense appropriations bill banned the funding of new GWEN tower construction, and a few months later, the GWEN program was cancelled by the US Air Force . The United States Coast Guard later outfitted a number of former GWEN sites to house the Nationwide Differential GPS system. GWEN was part of the Strategic Modernization Program designed to upgrade the nation's strategic communication system, thereby strengthening

340-747: A few specially licensed AM broadcasting stations. These channels are called clear channels , and they are required to broadcast at higher powers of 10 to 50 kW. Initially, broadcasting in the United States was restricted to two wavelengths: "entertainment" was broadcast at 360 meters (833 kHz), with stations required to switch to 485 meters (619 kHz) when broadcasting weather forecasts, crop price reports and other government reports. This arrangement had numerous practical difficulties. Early transmitters were technically crude and virtually impossible to set accurately on their intended frequency and if (as frequently happened) two (or more) stations in

408-466: A group or unit type designation that is already linked to a specific system/subsystem/center/central/set may use ( -FT, -IN) if the system/subsystem/center/central/set uses multiple of the group/unit and they are only distinguishable by length. This use is only for new assignments and will not be retroactive For example: Primary batteries (non-rechargeable) are designated using "BA"; Secondary type batteries (rechargeable) are designated using "BB". JETDS

476-518: A lower one for omnidirectional and a higher one for directional radiation with minima in certain directions. The power limit can also be depending on daytime and it is possible that a station may not operate at nighttime, because it would then produce too much interference. Other countries may only operate low-powered transmitters on the same frequency, again subject to agreement. International medium wave broadcasting in Europe has decreased markedly with

544-404: A poor vertical radiation pattern, and 195 electrical degrees (about 400 millivolts per meter using one kilowatt at one kilometre) is generally considered ideal in these cases. Mast antennas are usually series-excited (base driven); the feedline is attached to the mast at the base. The base of the antenna is at high electrical potential and must be supported on a ceramic insulator to isolate it from

612-436: A quarter- wavelength (about 310 millivolts per meter using one kilowatt at one kilometre) to 5/8 wavelength (225 electrical degrees; about 440 millivolts per meter using one kilowatt at one kilometre), while high power stations mostly use half-wavelength to 5/9 wavelength. The usage of masts taller than 5/9 wavelength (200 electrical degrees; about 410 millivolts per meter using one kilowatt at one kilometre) with high power gives

680-453: A system fault. The overall area of a GWEN Relay Node was approximately 11 acres (4.5 ha), approximately 700 feet (210 m) × 700 feet. It was surrounded on the perimeter by locked, 8-foot-high (2.4 m) chain-link fences topped with barbed wire. Typical site features included: The main GWEN antenna operated intermittently in the LF band at 150 to 175 kilohertz (kHz) (below the bottom of

748-531: A tentative initial operating capability for GWEN by January 1992. When doubts arose regarding the threat of electromagnetic pulse to permanently shut down communications, only 58 of the originally planned 240 GWEN towers were built. In 1994 a defense appropriations bill banned new towers from being built, and shortly after, the GWEN program was cancelled by the Air Force. Command and control messages originating at various military installations were transmitted on

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816-420: A vertical radiator wire. A popular choice for lower-powered stations is the umbrella antenna , which needs only one mast one-tenth wavelength or less in height. This antenna uses a single mast insulated from ground and fed at the lower end against ground. At the top of the mast, radial top-load wires are connected (usually about six) which slope downwards at an angle of 40–45 degrees as far as about one-third of

884-480: Is adequate for talk and news but not for high-fidelity music. However, many stations use audio bandwidths up 10 kHz, which is not hi-fi but sufficient for casual listening. In the UK, until 2024 most stations used a bandwidth of 6.3 kHz. However in 2024, Ofcom expanded the allowed bandwidth to 9khz, giving a noticeable improvement in quality. With AM, it largely depends on the frequency filters of each receiver how

952-616: Is assigned to: This system is separate from the "M" designation used in the Army Nomenclature System (MIL-STD-1464A). Items are given an Item Level which describes their hierarchy The core of the JETDS system is the combination of a Type Designation with an Item Name to specify a particular item. For example: The type designation is a unique series of letters and numbers which specifies an item. There are three basic forms of type designator used: The Type Designation

1020-433: Is available, (however digital radio still has coverage issues in many parts of Europe). Many countries in Europe have switched off or limited their MW transmitters since the 2010s. The term is a historic one, dating from the early 20th century, when the radio spectrum was divided on the basis of the wavelength of the waves into long wave (LW), medium wave, and short wave (SW) radio bands. For Europe, Africa and Asia

1088-477: Is denoted by addition of the letter(s) "X", "Y", or "Z". The first such modification would be denoted with an "X", the second with a "Y", the third with a "Z", the fourth with an "XX", etc. If simultaneous modifications are made that improve the equipment as well as affect power input, then both a modification letter (A, B, C, D, etc.) as well as a power requirement modification letter (X, Y, Z, etc.) will be used. For example: A pair of parentheses surrounding where

1156-424: Is designed specifically to provide training for one particular unit, then that unit may be specified. If it is a training equipment which can provide practice for various different sets/subsystems/systems etc., then that should be indicated with the appropriate letter indicators. For example: For example: A digit or digits in parentheses following the type designation letters indicates the type of ADPE included in

1224-503: Is made up of a two letter group indicator (from the table below), followed by a dash, a group number, followed by a slash, and 1-3 letters specifying the equipment it is "part of" or "used with" (see Table 1). If the group is unique and only "part of" or "used with" one particular equipment, that equipment may be specified. If the group may be used with multiple different items, then it is more appropriate to designate it more generally. For example: The type designation used to specify Units

1292-456: Is made up of a unit letter(s) indicator (from the table below), followed by a dash, a unit number, followed by a slash, and 1-3 letters specifying the equipment it is part of or used with (see Table 1). As with Group type designations, if the Unit is unique and is "part of" or "used with" only one particular equipment, that equipment may be specified. If the unit is used with multiple different items,

1360-443: Is placed after the type designation number to signify a modification to a specific equipment that still retains at least one-way interchangeability with all previous versions. Modification letters begin with "A" and proceed sequentially. For more information on Interchangeability (see below). Note: the letters "I", "O", "Q", "S", "T", "X", "Y", and "Z" are not to be used as modification letters For example: A suffix "(V)" following

1428-646: Is possible and is or was offered by some stations in the U.S., Canada, Mexico, the Dominican Republic, Paraguay, Australia, The Philippines, Japan, South Korea, South Africa, Italy and France. However, there have been multiple standards for AM stereo . C-QUAM is the official standard in the United States as well as other countries, but receivers that implement the technology are no longer readily available to consumers. Used receivers with AM Stereo can be found. Names such as "FM/AM Stereo" or "AM & FM Stereo" can be misleading and usually do not signify that

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1496-433: Is primarily only used by low-power stations; it is the preferred range for services with automated traffic, weather, and tourist information. The channel steps of 9 and 10 kHz require limiting the audio bandwidth to 9 and 10 kHz (at maximum without causing interference; ±4.5 kHz (9 kHz) and ±5 kHz (10 kHz) on each two sidebands) because the audio spectrum is transmitted twice on each side band . This

1564-516: Is the ITU-approved system for use outside North America and U.S. territories . Some HD Radio receivers also support C-QUAM AM stereo, although this feature is usually not advertised by the manufacturer. For broadcasting, mast radiators are the most common type of antenna used, consisting of a steel lattice guyed mast in which the mast structure itself is used as the antenna. Stations broadcasting with low power can use masts with heights of

1632-494: Is used in conjunction with an approved Item Name drawn from the H-6 Item Name Directory. For example: The type designation used to specify Systems, Subsystems, Centers, Central, and Sets is made up of a prefix AN/ , three type designation indicator letters, a hyphen, and a type designation number. The AN prefix signifies Army-Navy. The three type designation letters (chosen from the table below) specify where

1700-579: The AM broadcast band at 530 kHz). The peak broadcasting power was from 2,000 to 3,000 watts. The UHF antenna operated at 20 watts, between 225 and 400 megahertz (MHz). A 1998 U.S. Department of Transportation environmental impact survey that proposed repurposing a number of existing GWEN sites for use by the Nationwide Differential Global Positioning System listed the locations of 29 GWEN sites: Some of

1768-496: The FM broadcast band but require more energy and longer antennas. Digital modes are possible but have not reached momentum yet. MW was the main radio band for broadcasting from the beginnings in the 1920s into the 1950s until FM with a better sound quality took over. In Europe, digital radio is gaining popularity and offers AM stations the chance to switch over if no frequency in the FM band

1836-624: The Federal Communications Commission (FCC) to shut down, reduce power, or employ a directional antenna array at night in order to avoid interference with each other due to night-time only long-distance skywave propagation (sometimes loosely called ‘skip’). Those stations which shut down completely at night are often known as "daytimers". Similar regulations are in force for Canadian stations, administered by Industry Canada ; however, daytimers no longer exist in Canada,

1904-643: The United States Coast Guard in 1950, Canada in 1951 and the NSA in 1959 (though the NSA continued to use its own TSEC telecommunications security nomenclature ). In 1957 the U.S. Department of Defense approved a military standard for the nomenclature, MIL-STD-196. The system has been modified over time, with some types (e.g. carrier pigeon -B- ) dropped and others (e.g. computers and cryptographic equipment) added. The latest version, MIL-STD-196G,

1972-490: The ionosphere and return to Earth at much greater distances; this is called the skywave . At night, especially in winter months and at times of low solar activity, the lower ionospheric D layer virtually disappears. When this happens, MW radio waves can easily be received many hundreds or even thousands of miles away as the signal will be reflected by the higher F layer . This can allow very long-distance broadcasting, but can also interfere with distant local stations. Due to

2040-601: The last station having signed off in 2013, after migrating to the FM band . Many countries have switched off most of their MW transmitters in the 2010s due to cost-cutting and low usage of MW by the listeners. Among those are Germany, France, Russia, Poland, Sweden, the Benelux, Austria, Switzerland, Slovenia and most of the Balkans. Other countries that have no or few MW transmitters include Iceland, Ireland, Finland and Norway. Large networks of transmitters are remaining in

2108-486: The 225 to 400 MHz band and received by a network of unmanned relay stations, called "Relay Nodes", dispersed throughout the contiguous 48 states. The Relay Nodes would re-transmit these command and control messages to each other, and to Strategic Air Command operating locations and launch control centers using low frequencies in the 150-175 kHz range in order to take advantage of ground-hugging radio propagation similar to commercial AM radio stations. Distance between

AN/URC-117 Ground Wave Emergency Network - Misplaced Pages Continue

2176-591: The Air Force Weapons Laboratory ( Kirtland Air Force Base ) tested a small scale 'groundwave' transmission system in 1978-1982. Based on the groundwave concept's promise, USAF Headquarters issued a draft Program Management Directive (PMD) for a "Proliferated Groundwave Communications System (PGCS)" on 25 August 1981. The name of this proposed network system was changed from PGCS to Groundwave Emergency Network in February 1982 The Air Force placed

2244-533: The MW band consists of 120 channels with carrier frequencies from 531 to 1602 kHz spaced every 9 kHz. Frequency coordination avoids the use of adjacent channels in one area. The total allocated spectrum including the modulated audio ranges from 526.5 to 1606.5 kHz. Australia uses an expanded band up to 1701 kHz. North and South America use 118 channels from 530 to 1700 kHz using 10 kHz spaced channels. The range above 1610 kHz

2312-636: The MW band is thinning out, many local stations from the remaining countries as well as from North Africa and the Middle East can now be received all over Europe, but often only weak with much interference. In Europe, each country is allocated a number of frequencies on which high power (up to 2 MW) can be used; the maximum power is also subject to international agreement by the International Telecommunication Union (ITU). In most cases there are two power limits:

2380-512: The Relay Nodes were approximately 150–200 miles, determined by the ground wave transmission range. During initial operations, the Relay Nodes would receive and relay brief test messages every 20 minutes. The system had built-in redundancy, using packet switching techniques for reconstruction of connectivity if system damage occurred. Early in its lifetime, electrical interference problems caused by GWEN system operation began to surface. Since

2448-560: The UK, Spain and Romania. In the Netherlands and Scandinavia, some new idealistically driven stations have launched low power services on the former high power frequencies. This also applies to the ex-offshore pioneer Radio Caroline that now has a licence to use 648 kHz, which was used by the BBC World Service over decades. In Italy, the government closed its high power transmitters but low power private stations remain. As

2516-807: The audio is reproduced. This is a major disadvantage compared to FM and digital modes where the demodulated audio is more objective. Extended audio bandwidths cause interference on adjacent channels. Wavelengths in this band are long enough that radio waves are not blocked by buildings and hills and can propagate beyond the horizon following the curvature of the Earth; this is called the groundwave . Practical groundwave reception of strong transmitters typically extends to 200–300 miles (320–480 km), with greater distances over terrain with higher ground conductivity , and greatest distances over salt water. The groundwave reaches further on lower medium wave frequencies. Medium waves can also reflect off charged particle layers in

2584-542: The country and/or abroad), no longer having to broadcast weather and government reports on a different frequency than entertainment. Class A and B stations were segregated into sub-bands. In the US and Canada the maximum transmitter power is restricted to 50 kilowatts, while in Europe there are medium wave stations with transmitter power up to 2 megawatts daytime. Most United States AM radio stations are required by

2652-618: The end of the Cold War and the increased availability of satellite and Internet TV and radio, although the cross-border reception of neighbouring countries' broadcasts by expatriates and other interested listeners still takes place. In the late 20th century, overcrowding on the Medium wave band was a serious problem in parts of Europe contributing to the early adoption of VHF FM broadcasting by many stations (particularly in Germany). Due to

2720-474: The equipment designation should include only the indicators which are common or appropriate. If a unit could be described by multiple indicators, the indicator which best describes the unit's primary function should be used. The exception would be if there exists a unit indicator which can describe the unit's multiple functions (see examples below); if such a multi-function describing unit indicator exists, then it should be used. For example: A modification letter

2788-629: The equipment is used, what the equipment is, and what its purpose is. The type designation number helps specify the exact item; subsequent items with the same Installation/Type/Purpose are numbered sequentially (i.e. the next item developed after the AN/PRC-34 would be the AN/PRC-35). For example: * Additional info on Installation indicators: ** Additional info on Type of Equipment indicators: The type designation used to specify Groups (assemblies that are used in conjunction with others to function)

AN/URC-117 Ground Wave Emergency Network - Misplaced Pages Continue

2856-578: The frequency. Because such tall masts can be costly and uneconomic, other types of antennas are often used, which employ capacitive top-loading ( electrical lengthening ) to achieve equivalent signal strength with vertical masts shorter than a quarter wavelength. A "top hat" of radial wires is occasionally added to the top of mast radiators, to allow the mast to be made shorter. For local broadcast stations and amateur stations of under 5 kW, T- and L-antennas are often used, which consist of one or more horizontal wires suspended between two masts, attached to

2924-423: The ground. Shunt-excited masts, in which the base of the mast is at a node of the standing wave at ground potential and so does not need to be insulated from the ground, have fallen into disuse, except in cases of exceptionally high power, 1 MW or more, where series excitation might be impractical. If grounded masts or towers are required, cage or long-wire aerials are used. Another possibility consists of feeding

2992-678: The high demand for frequencies in Europe, many countries set up single frequency networks; in Britain , BBC Radio Five Live broadcasts from various transmitters on either 693 or 909 kHz. These transmitters are carefully synchronized to minimize interference from more distant transmitters on the same frequency. In Asia and the Middle East, many high-powered transmitters remain in operation. China , Indonesia , South Korea , North Korea , Japan , Thailand , Vietnam , Philippines , Saudi Arabia , Egypt , India , Pakistan and Bangladesh still use medium wave. Israel returns to mediumwave after

3060-584: The importance of the towers, stating they were not worth that kind of attention by the Soviet Union. Amid controversy and world geopolitical changes, GWEN's value diminished greatly in the post- Cold War environment, in addition to its existence being rendered moot by the sustained effectiveness of predecessor and follow-on systems ( Survivable Low Frequency Communication System and Minimum Essential Emergency Communication Network respectively). As early as 1990, legislative measures were enacted to terminate

3128-462: The initial towers had prompted groups of citizens in Massachusetts , Oregon , Pennsylvania , and California to organize to fight construction of GWEN towers in their areas. The groups believed that the presence of a GWEN node would increase the community's "strategic worth" in the eyes of the Soviet Union and thus invite attack. Responding to these groups, the Air Force repeatedly downplayed

3196-543: The ionosphere for propagation . It was thought that GWEN would use a ground-hugging wave for propagation and so be unaffected by the EMP. The network was conceived as an array of approximately 240 radio transceivers distributed across the continental USA which operated in the Low frequency (LF) radio band . Analysis showed that low-frequency (150-190 kilohertz) radio transmissions were largely unaffected by high-altitude EMP, and

3264-425: The item. For example: Maintenance equipment that is given a type designation is set up as AN/xxM, where the first two letters after the slash (signifying Installation and Type of equipment) are followed by an M. However, if a maintenance or test Unit or Group is considered a "part of" the item in question, it does not receive the M signifier. For example: A change in the power input voltage, phase, or frequency

3332-596: The limited number of available channels in the MW broadcast band, the same frequencies are re-allocated to different broadcasting stations several hundred miles apart. On nights of good skywave propagation, the skywave signals of a distant station may interfere with the signals of local stations on the same frequency. In North America, the North American Regional Broadcasting Agreement (NARBA) sets aside certain channels for nighttime use over extended service areas via skywave by

3400-416: The manufacturer maintains design control are not covered. Electronic material, from a military point of view, generally includes those electronic devices employed in data processing, detection and tracking (underwater, sea, land-based, air and space), recognition and identification, communications, aids to navigation, weapons control and evaluation, flight control, and electronics countermeasures. Nomenclature

3468-486: The mast or the tower by cables running from the tuning unit to the guys or crossbars at a certain height. Directional aerials consist of multiple masts , which need not to be of the same height. It is also possible to realize directional aerials for mediumwave with cage aerials where some parts of the cage are fed with a certain phase difference. For medium-wave (AM) broadcasting, quarter-wave masts are between 153 feet (47 m) and 463 feet (141 m) high, depending on

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3536-613: The most common antenna for broadcast reception is the ferrite-rod antenna , also known as a loopstick antenna. The high permeability ferrite core allows it to be compact enough to be enclosed inside the radio's case and still have adequate sensitivity. For weak signal reception or to discriminate between different signals sharing a common frequency directional antennas are used. For best signal-to-noise ratio these are best located outdoors away from sources of electrical interference. Examples of such medium wave antennas include broadband untuned loops, elongated terminated loops, wave antennas (e.g.

3604-416: The outbreak of Israel-Hamas war . China operates many single-frequency networks across the country. As of May 2023, many Japanese broadcasters like NHK broadcast in medium wave, with many high power transmitters operating across Japan. There are also some low power relay transmitters for rural areas. Some countries have stopped using mediumwave, including Malaysia and Singapore. Stereo transmission

3672-440: The plug-in's function, then the generic plug-in unit indicator (PL) will be used. For example: Type designators for groups and units like cables, waveguides, cords, etc. may also include a parenthetical "( -FT, -IN)" to designate the specified length. These type designators will not include a specified System/Subsystem/Center/Central/Set type designator after the / but will be given a more generic indicator like /U or /GR. However,

3740-545: The program. In 1994, new construction of GWEN towers were banned after a defense appropriations bill eliminated any funding for the towers for one year. A few months later, the United States Air Force announced that they would terminate the construction contract to build the remaining 25 towers, except for the money used to dismantle the system. Joint Electronics Type Designation System The Joint Electronics Type Designation System (JETDS) , which

3808-563: The radio will decode C-QUAM AM stereo, whereas a set labelled "FM Stereo/AM Stereo" or "AMAX Stereo" will support AM stereo. In September 2002, the United States Federal Communications Commission approved the proprietary iBiquity in-band on-channel (IBOC) HD Radio system of digital audio broadcasting , which is meant to improve the audio quality of signals. The Digital Radio Mondiale (DRM) system standardised by ETSI supports stereo and

3876-411: The reception of much longer distance signals (within a range of about 2,000 km or 1,200 miles). This can cause increased interference because on most channels multiple transmitters operate simultaneously worldwide. In addition, amplitude modulation (AM) is often more prone to interference by various electronic devices, especially power supplies and computers. Strong transmitters cover larger areas than on

3944-575: The same part of the country broadcast simultaneously the resultant interference meant that usually neither could be heard clearly. The Commerce Department rarely intervened in such cases but left it up to stations to enter into voluntary timesharing agreements amongst themselves. The addition of a third "entertainment" wavelength, 400 meters, did little to solve this overcrowding. In 1923, the Commerce Department realized that as more and more stations were applying for commercial licenses, it

4012-413: The stations were using LF, the chosen frequency was within 1 kHz of the operating frequency of nearby electrical carrier current systems. With GWEN handling constant voice, teletype and other data traffic, it caused interference to the power companies' diagnostic two kilohertz side carrier tone. When the side carrier tone disappeared due to interference from GWEN, the power grid would interpret that as

4080-482: The total height, where they are terminated in insulators and thence outwards to ground anchors . Thus the umbrella antenna uses the guy wires as the top-load part of the antenna. In all these antennas the smaller radiation resistance of the short radiator is increased by the capacitance added by the wires attached to the top of the antenna. In some rare cases dipole antennas are used, which are slung between two masts or towers. Such antennas are intended to radiate

4148-412: The type designation number and any modification letters indicates variable components or configurations for said Group/Set/Subsystem/System/Center/Central. A number may follow the parenthetical V to identify a specific configuration. For example: Note: A specific equipment should only be given a (V) signifier if it can be configured with different components, not simply because one of its components has

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4216-631: The type designation number would be located is used to signify an experimental or developmental model. Type designation number is not required but is useful for clarity. When the developmental model is ready for production, the parentheses are struck off. For example: Electronic type (non-rotating) servo amplifiers are designated "AM"; rotating type servo amplifiers are designated "PU". Plug-in Units which can be described by their function (like receiver, microphone, loudspeaker, etc.) will use those corresponding Unit indicators. If no indicator exists to describe

4284-416: The unit itself. For example: A suffix of "(C)" following the type designation number and any modification letters indicates an item which directly contains NSA-controlled cryptographic material. For example: A suffix of "-T n ", where n is a number, indicates equipment (Set, Subsystem, System, Center, or Central) designed to provide training in the operation of a specific set or multiple sets. If it

4352-407: The value of nuclear deterrence . The GWEN communication system, established in the late 1980s, was designed to transmit critical Emergency Action Messages (EAM) to United States nuclear forces. EMP can produce a sudden power surge over a widespread area that could overload unprotected electronic equipment and render it inoperable. In addition, EMP could interfere with radio transmissions that use

4420-653: Was adopted 16 February 1943 by the Joint Communications Board for all new Army and Navy airborne, radio, and radar equipment. Over time it was extended to cover the Marine Corps and the Navy's ship, submarine, amphibious, and ground electronic equipment. When the Air Force was established as a separate department, it continued the use of the system for electronic equipment. JETDS was adopted by

4488-483: Was issued in 2018. Medium wave Medium wave ( MW ) is a part of the medium frequency (MF) radio band used mainly for AM radio broadcasting . The spectrum provides about 120 channels with more limited sound quality than FM stations on the FM broadcast band . During the daytime, reception is usually limited to more local stations, though this is dependent on the signal conditions and quality of radio receiver used. Improved signal propagation at night allows

4556-426: Was not practical to have every station broadcast on the same three wavelengths. On 15 May 1923, Commerce Secretary Herbert Hoover announced a new bandplan which set aside 81 frequencies, in 10 kHz steps, from 550 kHz to 1350 kHz (extended to 1500, then 1600 and ultimately 1700 kHz in later years). Each station would be assigned one frequency (albeit usually shared with stations in other parts of

4624-671: Was previously known as the Joint Army-Navy Nomenclature System (AN System. JAN) and the Joint Communications-Electronics Nomenclature System , is a method developed by the U.S. War Department during World War II for assigning an unclassified designator to electronic equipment. In 1957, the JETDS was formalized in MIL-STD-196 . Computer software and commercial unmodified electronics for which

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