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62-827: The initial NARBA bandplan , also known as the "Havana Treaty", was signed by the United States, Canada, Mexico, Cuba, the Dominican Republic, and Haiti on December 13, 1937, and took effect March 29, 1941. A series of modifications and adjustments followed, also under the NARBA name. NARBA's provisions were largely supplanted in 1983, with the adoption of the Regional Agreement for the Medium Frequency Broadcasting Service in Region 2 (Rio Agreement), which covered

124-409: A "Radio Moving Day", but he refused on the grounds that "My experience has been that proclamations by the mayor mean just exactly nothing and I issue as few as I can.") The frequency changes affected "about a thousand stations in seven countries". The following chart reviews the assignments before and after March 29, 1941, including information about individual U.S. and Canadian stations, and summarizes

186-509: A clear channel were known as Class I-B. The Agreement assigned six Class I-A frequencies each to Mexico and Canada, and one to Cuba. Reflecting the existence of improved radio design, the Agreement also reduced the "same market" minimum frequency separation from 50 to 40 kHz. (Mexico elected to further adopt a 30 kHz "same market" spacing, unless this was in conflict with an adjoining nation's "border zone" allocations.) This closer spacing

248-560: A letter to the editor of Wireless Engineer in 1942. For example, the approximate geometric mean of band 7 is 10 MHz, or 10  Hz. The band name "tremendously low frequency" (TLF) has been used for frequencies from 1–3 Hz (wavelengths from 300,000–100,000 km), but the term has not been defined by the ITU. Frequency bands in the microwave range are designated by letters. This convention began around World War II with military designations for frequencies used in radar , which

310-483: A move to 2.4 GHz spread spectrum RC control systems. Licensed amateur radio operators use portions of the 6-meter band in North America. Industrial remote control of cranes or railway locomotives use assigned frequencies that vary by area. Radar applications use relatively high power pulse transmitters and sensitive receivers, so radar is operated on bands not used for other purposes. Most radar bands are in

372-455: A station's existing vertical radiator towers, an important factor for readjusting directional antenna parameters to accommodate the new frequency. Individual stations were specified to be Class I, II III or IV, with the class determining the maximum power a station could use and its interference protection standards. In all of the participating countries Class I and II stations were exclusively assigned to Clear Channel frequencies, while Class III

434-407: A traditional name. For example, the term high frequency (HF) designates the wavelength range from 100 to 10 metres, corresponding to a frequency range of 3 to 30 MHz. This is just a symbol and is not related to allocation; the ITU further divides each band into subbands allocated to different services. Above 300 GHz, the absorption of electromagnetic radiation by Earth's atmosphere

496-431: Is a fixed resource which is in demand by an increasing number of users, the radio spectrum has become increasingly congested in recent decades, and the need to utilize it more effectively is driving modern telecommunications innovations such as trunked radio systems , spread spectrum , ultra-wideband , frequency reuse , dynamic spectrum management , frequency pooling, and cognitive radio . The frequency boundaries of

558-420: Is a small frequency band (a contiguous section of the range of the radio spectrum) in which channels are usually used or set aside for the same purpose. To prevent interference and allow for efficient use of the radio spectrum, similar services are allocated in bands. For example, broadcasting, mobile radio, or navigation devices, will be allocated in non-overlapping ranges of frequencies. For each radio band,

620-478: Is so great that the atmosphere is effectively opaque, until it becomes transparent again in the near-infrared and optical window frequency ranges. These ITU radio bands are defined in the ITU Radio Regulations . Article 2, provision No. 2.1 states that "the radio spectrum shall be subdivided into nine frequency bands, which shall be designated by progressive whole numbers in accordance with

682-439: Is the part of the electromagnetic spectrum with frequencies from 3  Hz to 3,000  GHz (3  THz ). Electromagnetic waves in this frequency range, called radio waves , are widely used in modern technology, particularly in telecommunication . To prevent interference between different users, the generation and transmission of radio waves is strictly regulated by national laws, coordinated by an international body,

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744-552: Is used in coastal waters and relatively short-range communication between vessels and to shore stations. Radios are channelized, with different channels used for different purposes; marine Channel 16 is used for calling and emergencies. Amateur radio frequency allocations vary around the world. Several bands are common for amateurs worldwide, usually in the HF part of the spectrum. Other bands are national or regional allocations only due to differing allocations for other services, especially in

806-513: Is valuable in providing radio programming to sparsely settled areas using high-powered transmitters. However, it also leads to the need for international cooperation in station assignments, to avoid mutually interfering signals. In an effort to rationalize assignments, a major reallocation went into force in the U.S. on November 11, 1928, following the standards set by the Federal Radio Commission 's (FRC) General Order 40 . At that time,

868-670: The Apalachicola River , which would be on Eastern Standard Time year-round). A similar bill was proposed for the Canadian province of Ontario by its legislative assembly in late 2020, which would have a similar effect on the province if passed. For those in the United States, daylight saving time for the Eastern Time Zone was introduced by the Uniform Time Act of 1966, which specified that daylight saving time would run from

930-565: The ITU and the local regulating agencies like the US Federal Communications Commission (FCC) and voluntary best practices help avoid interference. As a matter of convention, the ITU divides the radio spectrum into 12 bands, each beginning at a wavelength which is a power of ten (10 ) metres, with corresponding frequency of 3×10   hertz , and each covering a decade of frequency or wavelength. Each of these bands has

992-691: The International Telecommunication Union (ITU). Different parts of the radio spectrum are allocated by the ITU for different radio transmission technologies and applications; some 40 radiocommunication services are defined in the ITU's Radio Regulations (RR). In some cases, parts of the radio spectrum are sold or licensed to operators of private radio transmission services (for example, cellular telephone operators or broadcast television stations). Ranges of allocated frequencies are often referred to by their provisioned use (for example, cellular spectrum or television spectrum). Because it

1054-535: The VHF and UHF parts of the radio spectrum. Citizens' band radio is allocated in many countries, using channelized radios in the upper HF part of the spectrum (around 27 MHz). It is used for personal, small business and hobby purposes. Other frequency allocations are used for similar services in different jurisdictions, for example UHF CB is allocated in Australia. A wide range of personal radio services exist around

1116-748: The data rate that can be transmitted. Below about 30 kHz, audio modulation is impractical and only slow baud rate data communication is used. The lowest frequencies that have been used for radio communication are around 80 Hz, in ELF submarine communications systems built by a few nations' navies to communicate with their submerged submarines hundreds of meters underwater. These employ huge ground dipole antennas 20–60 km long excited by megawatts of transmitter power, and transmit data at an extremely slow rate of about 1 bit per minute (17 millibits per second , or about 5 minutes per character). The highest frequencies useful for radio communication are limited by

1178-529: The far infrared and mid infrared bands. Because it is a fixed resource, the practical limits and basic physical considerations of the radio spectrum, the frequencies which are useful for radio communication , are determined by technological limitations which are impossible to overcome. So although the radio spectrum is becoming increasingly congested, there is no possible way to add additional frequency bandwidth outside of that currently in use. The lowest frequencies used for radio communication are limited by

1240-563: The microwave part of the spectrum, although certain important applications for meteorology make use of powerful transmitters in the UHF band. North American Eastern Standard Time Zone The Eastern Time Zone ( ET ) is a time zone encompassing part or all of 23 states in the eastern part of the United States , parts of eastern Canada , and the state of Quintana Roo in Mexico . On

1302-527: The AM band was defined as 96 frequencies, running in 10 kilocycle-per-second (kHz) steps from 550 to 1500 kHz, which were divided into what became known as "Local", "Regional", and "Clear Channel" frequencies. The only provision the FRC made addressing international concerns was that six frequencies — 690, 730, 840, 910, 960, and 1030 — were designated for exclusive Canadian use. On May 5, 1932, through an exchange of letters,

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1364-456: The Bahamas being granted use of the 1540 kHz clear channel by the U.S. The interim agreement expired on March 29, 1949, and there was great difficulty in agreeing on a replacement, in particular due to Mexican objections, which led to two failed conferences. A new NARBA agreement, to be effective for five years after ratification, was finally signed at Washington, D.C., on November 15, 1950, for

1426-409: The Bahamas, Canada, Cuba, the Dominican Republic, Jamaica and the United States. Mexico, which had withdrawn from the conference, and Haiti, which did not participate, were to be given a chance to subscribe. (The United States and Mexico made a bilateral agreement in 1957.) This agreement formally added 540 kHz as a clear channel frequency, and also provided for Cuba to share six, and Jamaica two, of

1488-587: The Bahamas, the Dominican Republic, and United States because those countries have not formally abrogated NARBA. The United States also has active bilateral agreements with Canada ("Agreement Between the Government of the United States of America and the Government of Canada Relating to the AM Broadcasting Service in the Medium Frequency Band" (1984) and Mexico ("Agreement Between the Government of

1550-798: The Eastern Time Zone. They are: Five states are divided between the Eastern Time Zone and the Central Time Zone . The following locations observe Eastern Time: Additionally, Phenix City, Alabama , and several nearby communities in Russell County, Alabama , unofficially observe Eastern Time. This is due to their close proximity to Columbus, Georgia , which is on Eastern Time. In addition Smiths Station in Lee County along with Valley and Lanett in Chambers county honor Eastern Time. The Bahamas and Haiti officially observe both Eastern Standard Time during

1612-456: The ITU has a band plan (or frequency plan ) which dictates how it is to be used and shared, to avoid interference and to set protocol for the compatibility of transmitters and receivers . Each frequency plan defines the frequency range to be included, how channels are to be defined, and what will be carried on those channels. Typical definitions set forth in a frequency plan are: The actual authorized frequency bands are defined by

1674-465: The U.S. and Canada informally endorsed and expanded the 1928 standards, including recognition of Canadian use of 540 kHz. During the 1930s, Canada also began using 1510 kHz, while in 1934 the U.S. authorized two experimental high-fidelity stations on each of 1530 and 1550 kHz. By 1939, Cuban stations existed on frequencies as high as 1600 kHz. As other countries, especially Mexico and Cuba, developed their own radio broadcasting services,

1736-434: The U.S. clear channel allocations. Some provisions remained controversial, and this version of the treaty wasn't ratified by the United States until early 1960. In 1980, Cuba gave the required one year notification that it was withdrawing from the NARBA treaty. The NARBA treaties have been substantially superseded by the "Regional Agreement for the Medium Frequency Broadcasting Service in Region 2" (Rio Agreement), which covers

1798-471: The U.S., Canada, Cuba, the Dominican Republic and Mexico, was held from January 14–30, 1941 in Washington, D.C., in order to coordinate the upcoming changes. With a few exceptions the frequency shifts were scheduled to be implemented at 0800 Greenwich Mean Time (3 a.m. E.S.T. ) on March 29, 1941, which was informally known as "moving day". (Philadelphia stations petitioned mayor Robert Lamberton to declare

1860-954: The United States of America and the Government of the United Mexican States Relating to the AM Broadcasting Service in the Medium Frequency Band" (1986)).       • Agreement text (pages 1398–1400)       • Canadian station assignments by frequency (pages 1408–1410)       • Cuban station assignments by frequency (pages 1411–1414)       • Dominican Republic station assignments by frequency (page 1414)       • Haitian station assignments by frequency (page 1415)       • Mexican station assignments by frequency (pages 1415–1420)       • United States station assignments by frequency (pages 1421–1443) Bandplan The radio spectrum

1922-515: The United States, with the exception of Saskatchewan , Yukon , and several other very localized areas. None of those areas are in the Eastern Time Zone. The boundary between time zones is set forth in the Code of Federal Regulations , with the boundary between the Eastern and Central Time Zones being specifically detailed in 49 C.F.R. part 71. Washington, D.C. , and 17 states are located entirely within

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1984-467: The VHF and UHF parts of the spectrum, are allocated for communication between fixed base stations and land mobile vehicle-mounted or portable transceivers. In the United States these services are informally known as business band radio. See also Professional mobile radio . Police radio and other public safety services such as fire departments and ambulances are generally found in the VHF and UHF parts of

2046-417: The absorption of microwave energy by the atmosphere. As frequency increases above 30 GHz (the beginning of the millimeter wave band), atmospheric gases absorb increasing amounts of power, so the power in a beam of radio waves decreases exponentially with distance from the transmitting antenna. At 30 GHz, useful communication is limited to about 1 km, but as frequency increases the range at which

2108-502: The allocation still dedicated to television, TV-band devices use channels without local broadcasters. The Apex band in the United States was a pre-WWII allocation for VHF audio broadcasting; it was made obsolete after the introduction of FM broadcasting. Airband refers to VHF frequencies 108 to 137 MHz, used for navigation and voice communication with aircraft. Trans-oceanic aircraft also carry HF radio and satellite transceivers. The greatest incentive for development of radio

2170-416: The band by "stretching out" the existing assignments, achieved by following a table which in most cases moved all the stations on a common frequency to a new, higher, dial position. This provided gaps of unassigned frequencies, most of which became clear channels allocated to Mexico and Canada. A majority of the frequency shifts were limited to between 10 and 30 kHz, which conserved the electrical height of

2232-467: The entire Western hemisphere, and was signed at Rio de Janeiro, Brazil in 1981, taking effect on July 1, 1983 at 08:00 UTC . The interference protection criteria in the Rio Agreement are significantly different from NARBA's, and the concept of clear channel stations is eliminated. In adopting this agreement, the Bahamas and Canada declared their intent to renounce their adherence to NARBA. However, much of

2294-568: The entire Western hemisphere. However, current AM band assignments in North America largely reflect the standards first established by the NARBA agreements. Organized AM (mediumwave) radio broadcasting began in the early 1920s, and the United States soon dominated the North American airwaves, with more than 500 stations by the end of 1922. Due to a change in the ionosphere after the sun sets, nighttime signals from AM band stations are reflected for distances extending for hundreds of kilometers. This

2356-536: The first Sunday in November. In Canada, daylight saving time begins and ends on the same days and at the same times as it does in the United States. In Canada , the following provinces and territories are part of the Eastern Time Zone: Within Canada, as with the United States, the Eastern Time Zone is the most populous time zone. Most of Canada observes daylight saving time synchronously with

2418-599: The following table". The table originated with a recommendation of the fourth CCIR meeting, held in Bucharest in 1937, and was approved by the International Radio Conference held at Atlantic City, NJ in 1947. The idea to give each band a number, in which the number is the logarithm of the approximate geometric mean of the upper and lower band limits in Hz, originated with B. C. Fleming-Williams, who suggested it in

2480-503: The high-powered English-language " border blaster " stations that had been directing their programming toward the U.S. and causing significant interference to U.S. and Canadian stations. However, an initial international meeting held in Mexico City in the summer of 1933 failed, primarily due to a lack of agreement over how many clear channel frequencies would be assigned to Mexico. In 1937, a series of radio conferences, this time successful,

2542-446: The increasing size of transmitting antennas required. The size of antenna required to radiate radio power efficiently increases in proportion to wavelength or inversely with frequency. Below about 10 kHz (a wavelength of 30 km), elevated wire antennas kilometers in diameter are required, so very few radio systems use frequencies below this. A second limit is the decreasing bandwidth available at low frequencies, which limits

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2604-452: The largest use of these bands has been by short-range low-power communications systems, since users do not have to hold a radio operator's license. Cordless telephones , wireless computer networks , Bluetooth devices, and garage door openers all use the ISM bands. ISM devices do not have regulatory protection against interference from other users of the band. Bands of frequencies, especially in

2666-654: The last Sunday of April until the last Sunday in October. The act was amended to make the first Sunday in April the beginning of daylight saving time beginning in 1987. Later, the Energy Policy Act of 2005 extended daylight saving time in the United States, beginning in 2007. Since then, local times change at 2:00 a.m. EST to 3:00 a.m. EDT on the second Sunday in March, and return from 2:00 a.m. EDT to 1:00 a.m. EST on

2728-410: The most significant changes: A series of modifications would follow the initial treaty, which was scheduled to expire on March 29, 1946. In early 1946, a three-year interim agreement gave Cuba expanded allocations, including the right to share five U.S., three Canadian, and two Mexican clear channel allocations, plus operate high-powered stations on some regional frequencies. The changes also resulted in

2790-478: The need arose to standardize engineering practices, reduce interference, and more fairly distribute clear channel assignments. Moreover, the development of better frequency control, and especially directional antennas, made it possible for additional stations to operate on the same or close by frequencies without significantly increasing interference. A key objective for the United States was that, in exchange for receiving clear channel assignments, Mexico would eliminate

2852-406: The radio spectrum are a matter of convention in physics and are somewhat arbitrary. Since radio waves are the lowest frequency category of electromagnetic waves , there is no lower limit to the frequency of radio waves. Radio waves are defined by the ITU as: "electromagnetic waves of frequencies arbitrarily lower than 3000 GHz, propagated in space without artificial guide". At the high frequency end

2914-455: The radio spectrum is bounded by the infrared band. The boundary between radio waves and infrared waves is defined at different frequencies in different scientific fields. The terahertz band , from 300 gigahertz to 3 terahertz, can be considered either as microwaves or infrared. It is the highest band categorized as radio waves by the International Telecommunication Union . but spectroscopic scientists consider these frequencies part of

2976-608: The second Sunday in March, at 2:00 a.m. EST, clocks are advanced to 3:00 a.m. EDT, creating a 23 hour day. On the first Sunday in November, at 2:00 a.m. EDT, clocks are moved back to 1:00 a.m. EST, which results in a 25 hour day. The boundaries of the Eastern Time Zone have moved westward since the Interstate Commerce Commission (ICC) took over time-zone management from railroads in 1938. The easternmost and northernmost counties in Kentucky were added to

3038-595: The spectrum. Trunking systems are often used to make most efficient use of the limited number of frequencies available. The demand for mobile telephone service has led to large blocks of radio spectrum allocated to cellular frequencies . Reliable radio control uses bands dedicated to the purpose. Radio-controlled toys may use portions of unlicensed spectrum in the 27 MHz or 49 MHz bands, but more costly aircraft, boat, or land vehicle models use dedicated radio control frequencies near 72 MHz to avoid interference by unlicensed uses. The 21st century has seen

3100-426: The structure introduced by that treaty remained intact. On June 8, 1988 another conference held at Rio de Janeiro, this time under the auspices of the International Telecommunication Union , adopted provisions effective July 1, 1990 to add ten AM band frequencies within Region 2, commonly known as the " expanded band ", and running from 1610 kHz to 1700 kHz. The 1950 NARBA provisions are still in effect for

3162-464: The term has not been defined by the ITU. Broadcast frequencies: Designations for television and FM radio broadcast frequencies vary between countries, see Television channel frequencies and FM broadcast band . Since VHF and UHF frequencies are desirable for many uses in urban areas, in North America some parts of the former television broadcasting band have been reassigned to cellular phone and various land mobile communications systems. Even within

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3224-468: The waves can be received decreases. In the terahertz band above 300 GHz, the radio waves are attenuated to zero within a few meters due to the absorption of electromagnetic radiation by the atmosphere (mainly due to ozone , water vapor and carbon dioxide ), which is so great that it is essentially opaque to electromagnetic emissions, until it becomes transparent again near the near-infrared and optical window frequency ranges. A radio band

3286-400: The winter months and Eastern Daylight Time during the summer months. Cuba generally follows the U.S. with Eastern Standard Time in the winter, and Eastern Daylight Time in the summer, but the exact day of change varies year to year. The Cayman Islands and Jamaica use Eastern Standard Time year-round. The Turks and Caicos Islands followed Eastern Time with daylight saving until 2015, when

3348-422: The world, usually emphasizing short-range communication between individuals or for small businesses, simplified license requirements or in some countries covered by a class license, and usually FM transceivers using around 1 watt or less. The ISM bands were initially reserved for non-communications uses of RF energy, such as microwave ovens , radio-frequency heating, and similar purposes. However, in recent years

3410-625: The zone in the 1940s, and in 1961 most of the state went Eastern. In 2000, Wayne County , on the Tennessee border, switched from Central to Eastern Time. Within the United States, the Eastern Time Zone is the most populous region, with nearly half of the country's population. In March 2019, the Florida Legislature passed a bill requesting authorization from Congress for year-round daylight saving time, which would effectively put Florida on Atlantic Standard Time year-round (except for west of

3472-529: Was held in Havana, Cuba, and the initial NARBA agreement was signed on December 13, 1937 by representatives from the United States, Canada, Cuba, Mexico, the Dominican Republic and Haiti. The most significant change was the formal addition of ten broadcasting frequencies, from 1510 to 1600 kHz, with the 106 available frequencies divided into Clear Channel (59 frequencies), Regional (41) and Local (6) designations. The official lower limit remained at 550 kHz, as it

3534-474: Was not possible to add stations at the bottom of the broadcast band due to the need to protect 500 kHz — a maritime international distress frequency — from interference. (Although operation on 540 kHz was not covered by the Agreement, unofficially it became an additional Canadian clear channel frequency.) Under the Agreement, most existing stations operating on 740 kHz or higher would have to change frequencies. Open frequencies were created throughout

3596-405: Was particularly important in the case of the two highest Local frequencies, 1420 and 1500 kHz, as stations on these frequencies were being moved to 1450 and 1490 kHz, a 40 kHz separation. According to the Agreement's provisions, its implementation was to take place within one year after its adoption by the pact's four main signatories — the United States, Canada, Cuba and Mexico. Cuba

3658-425: Was synonymous with a Regional frequency assignment. In the United States, Class IV stations were only assigned to Local frequencies, although in other countries they were assigned to both Local and Regional ones. A major change was the provision that some clear channels were allocated to be used simultaneously by two stations — those maintaining sole use of a frequency were classified as Class I-A, while stations sharing

3720-610: Was the first application of microwaves. There are several incompatible naming systems for microwave bands, and even within a given system the exact frequency range designated by a letter may vary somewhat between different application areas. One widely used standard is the IEEE radar bands established by the US Institute of Electrical and Electronics Engineers . The band name "tremendously low frequency" (TLF) has been used for frequencies from 1–3  Hz (wavelengths of 300,000–100,000 km), but

3782-413: Was the first to ratify, on December 22, 1937, and was followed by the U.S. on June 15, 1938 and Canada on November 29, 1938. While waiting on Mexico, in 1939 the U.S. and Canada completed a frequency agreement based on the treaty standards. Mexico finally approved the treaty on December 29, 1939, and work commenced on adopting its wide-ranging provisions. An engineering conference, with representatives from

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3844-478: Was the need to communicate with ships out of visual range of shore. From the very early days of radio, large oceangoing vessels carried powerful long-wave and medium-wave transmitters. High-frequency allocations are still designated for ships, although satellite systems have taken over some of the safety applications previously served by 500 kHz and other frequencies. 2182 kHz is a medium-wave frequency still used for marine emergency communication. Marine VHF radio

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