Citizens band radio (CB radio) is a land mobile radio system, a system allowing short-distance one-to-many bidirectional voice communication among individuals, using two-way radios operating near 27 MHz (or the 11-m wavelength) in the high frequency or shortwave band. Citizens band is distinct from other personal radio service allocations such as FRS, GMRS, MURS, UHF CB and the Amateur Radio Service ("ham" radio). In many countries, CB operation does not require a license and may be used for business or personal communications.

Like many other land mobile radio services, multiple radios in a local area share a single frequency channel, but only one can transmit at a time. The radio is normally in receive mode to receive transmissions of other radios on the channel; when users want to communicate they press a "push to talk" button on their radio, which turns on their transmitter. Users on a channel must take turns transmitting. In the US and Canada, and in the EU and the UK, transmitter power is limited to 4 watts when using AM and FM and 12 W PEP when using SSB.

CB radios using an omni-directional vertical antenna typically have a range of about 5 km to 30 km depending on terrain, for line of sight communication; however, various radio propagation conditions may intermittently allow communication over much greater distances. Base stations however may be connected to a directional Yagi–Uda antenna commonly called a Beam or a Yagi. Yagi–Uda antennae focus the transmitted signal in a particular direction while at the same time minimising the reception of signals coming from the rear of the antenna. Using a Yagi-Uda antenna can increase range substantially because the transmitted signal will travel farther while the rejection of received signals coming from the rear will simultaneously reduce unwanted incoming signals. To use a Yagi-Uda antenna one typically needs to also use a rotator for the antenna mast to turn the antenna to the desired direction much as Television antennas are sometimes turned to maximise TV reception.

Multiple countries have created similar radio services, with varying technical standards and requirements for licensing. While they may be known by other names, such as the General Radio Service in Canada,^[1] they often use similar frequencies (26–28 MHz) and have similar uses, and similar technical standards. Although licenses may be required, eligibility is generally simple. Some countries also have personal radio services in the UHF band, such as the European PMR446 and the Australian UHF CB.

History

United States

Origins

The citizens band radio service originated in the United States as one of several personal radio services regulated by the Federal Communications Commission (FCC). These services began in 1945 to permit citizens a radio band for personal communication (e.g., radio-controlled model airplanes and family and business communications). In 1948, the original CB radios were designed for operation on the 460–470 MHz UHF band.^[2] There were two classes of CB radio: "A" and "B". Class B radios had simpler technical requirements, and were limited to a smaller frequency range. Al Gross established the Citizens Radio Corporation during the late 1940s to manufacture class B handhelds for the general public.^[3]: 13 Originally designed for use by the public sector, the Citizens Radio Corporation sold over 100,000 units, primarily to farmers and the US Coast Guard.^[4]

Ultra-high frequency (UHF) radios, at the time, were neither practical nor affordable for the average consumer. On September 11, 1958^[3]: 14 CB service class D was created on 27 MHz, and this band became what is commonly known today as "Citizens Band". Only 23 channels were available at the time; the first 22 were taken from the former amateur radio service 11-meter band, and channel 23 was shared with radio-controlled devices. Some hobbyists continue to use the designation "11 meters" to refer to the Citizens Band and adjoining frequencies. Part 95 of the Code of Federal Regulations regulates the class D CB service, on the 27 MHz band, since the 1970s and continuing today.^[5] Most of the 460–470 MHz band was reassigned for business and public-safety use; CB Class A is the forerunner of the General Mobile Radio Service (GMRS). CB Class B is a more distant ancestor of the Family Radio Service. The Multi-Use Radio Service is another two-way radio service in the VHF high band. An unsuccessful petition was filed in 1973 to create a CB Class E service at 220 MHz, (part of the amateur radio 1.25-meter band at the time) which was opposed by amateur radio organizations and others.^[6] There are several other classes of personal radio services for specialized purposes (such as remote control devices).

During the 1960s, the service was used by small businesses (e.g., electricians, plumbers, carpenters), truck drivers and radio hobbyists. By the late 1960s, advances in solid-state electronics allowed the weight, size, and cost of the radios to fall, giving the public access to a communications medium previously only available to specialists.^[7] CB clubs were formed; a CB slang language evolved alongside ten-code, similar to those used in emergency services.

1970s popularity

After the 1973 oil crisis, the U.S. government imposed a nationwide 55 mph speed limit, and fuel shortages and rationing were widespread. Drivers (especially commercial truckers) used CB radios to locate service stations with better supplies of fuel, to notify other drivers of speed traps, and to organize blockades and convoys in a 1974 strike protesting the new speed limit and other trucking regulations.^[8] The radios were crucial for independent truckers; many were paid by the mile, and the 55 mph speed limit lowered their productivity.^[7]

Their use spread further into the general population in the US in the middle of the 1970s. Originally, CB (named Citizens Radio by the Federal Communications Commission as of 1972) required the use of a callsign in addition to a purchased license ($20 in the early 1970s, reduced to $4 on March 1, 1975); however, when the CB craze was at its peak many people ignored the requirement and invented their own nicknames (known as "handles"). Lax enforcement of the rules on authorized use of CB radio led to widespread further disregard of the regulations (such as for antenna height, distance communications, licensing, call signs, and transmitter power). Individual licensing came to an end on April 28, 1983.^[9]

The increased use of CB radios in 1970s had made its way into films, television, and music by the late 1970s. Films such as Smokey and the Bandit (1977), Breaker! Breaker! (1977), Citizens Band (a.k.a. Handle with Care) (1977), and Convoy (1978), made heavy reference to the phenomenon, as did television series such as Movin' On (debuted in 1974), The Dukes of Hazzard (debuted in 1979) and the animated series CB Bears (debuted in 1977) helped cement CB radio's status as a nationwide craze in the United States over the mid- to late-1970s. The phenomenon also inspired several popular and country music songs in 1975 and 1976:

• C. W. McCall's novelty song "Convoy" (1975), which climbed to #1 in the Billboard Hot 100 in January 1976, to #2 in the UK Charts during the spring of 1976, and inspiring the 1978 film of the same name. In the UK, BBC Radio One DJs Dave Lee Travis and Paul Burnett covered the song with an altered UK song text, released as "Convoy GB" under the moniker Laurie Lingo & the Dipsticks, chart-peaking at #4 in the spring of 1976.
• Dave Dudley's novelty Country music song Me and ol' CB from 1975, which peaked #10 in the US charts and #8 in Canadian charts.
• "The White Knight", a novelty country music song made famous by Jay Huguely, who — recording as Cledus Maggard & The Citizen's Band — enjoyed a brief run of national popularity with the song when it became popular in 1976.^[10]
• "Colorado Call" by Shad O'Shea & the 18 Wheelers was another early 1976 hit song based on the CB-ing truckers myth, reaching the national US charts.
• "'Round the World with the Rubber Duck" is a sequel to "Convoy", recorded by C.W. McCall. It was released in late spring 1976, and peaked at #1 in the Billboard Bubbling Under Hot 100 charts.
• "One Piece At A Time" by Johnny Cash (1976), peaked in the UK charts at #12 in early summer.
• The Outlaws's country rock song Breaker-Breaker lyrics are capitalizing on the fad. The record peaked at #94 in Billboard's Hot 100 in the spring of 1976.
• "Teddy Bear" by Red Sovine (1976) charted in the UK at #6 in late summer.
• Rod Hart's "C.B. Savage", a gay-themed country novelty song about truckers plagued by a mysterious effeminate CB aficionado.^[11][12]

Betty Ford, the former First Lady of the United States, used the CB handle "First Mama".^[13]

Voice actor Mel Blanc was also an active CB operator, often using "Bugs" or "Daffy" as his handle and talking on the air in the Los Angeles area in one of his many voice characters. He appeared in an interview (with clips having fun talking to children on his home CB radio station) in the NBC Knowledge television episode about CB radio in 1978. Similar to Internet chat rooms a quarter-century later, CB allowed people to get to know one another in a quasi-anonymous manner.

Originally, the U.S. had 23 CB channels; the 40 channel band plan was implemented in 1977. Two more channels between 22 & 23, commonly referred to as 22A & 22B, were available. Several people had 22A, but few had 22B. In the early 1970s Radio Shack sold a "base station" CB radio that contained a crystal for each of the 23 channels, two extra slots existed, and one could order the 22A & 22B crystals for an easy plug-in. Channel 9 was officially reserved for emergency use by the FCC in 1969.^[14]: 12 Channel 10 was originally often used for highway travel communications east of the Mississippi River, and channel 19 west of the Mississippi; channel 19 then became the preferred highway channel in most areas, as it did not have adjacent-channel interference problems with channel 9. Many CBers called channel 19 "the trucker's channel". The FCC originally restricted channel 11 for use as the calling channel.

The original FCC output power limitation for CB radios was "5 watts DC input to the final amplifier stage", which was a reference to the earlier radios equipped with tubes. With solid state radios becoming more common in the 1970s, the FCC revised this specification at the same time the authorized channels were increased to 40. The current specification is simply "4 watts output (AM) or 12 watts output (SSB)" as measured at the antenna connector on the back of the radio. The old specification was often used in false advertising by some manufacturers who would claim their CB radios had "5 watts" long after the specification had changed to 4 watts output. The older 23 channel radios built under the old specifications typically had an output of around 3.5 to 3.8 watts output when measured at the antenna connector. The FCC simply rounded up the old "5 watts DC input to the final amplifier stage" specification to the new "4 watts output as measured at the antenna connector on the back of the radio", resulting in a far simpler and easier specification.

Initially, the FCC intended for CB to be the "poor man's business-band radio", and CB regulations were structured similarly to those regulating the business band radio service. Until 1975,^[14]: 14 only channels 9–14 and 23^[a] could be used for "interstation" calls (to other licensees). Channels 1–8 and 15–22 were reserved for "intrastation" communications (among units with the same license).^[b] After the inter-station/intra-station rule was dropped, channel 11 was reserved as a calling frequency (for the purpose of establishing communications); however, this was withdrawn in 1977.^[14]: 120 During this early period, many CB radios had "inter-station" channels colored on their dials, while the other channels were clear or normally colored.^[c] It was common for a town to adopt an inter-station channel as its "home" channel. This helped prevent overcrowding on channel 11, enabling a CBer to monitor a town's home channel to contact another CBer from that town instead of a making a general call on channel 11.

Boating and the U.S. Coast Guard

Since the price of CB was dropping and VHF Marine Band was still expensive, many boaters installed CB radios. Business caught on to this market, and introduced marine CBs containing a weather band (WX). There was much controversy over whether the Coast Guard should monitor CB radio, but for safety they did so, using Motorola base stations at their search and rescue stations. The Coast Guard stopped this practice in the late 1980s and recommends VHF Marine Band radios for boaters.^[15]

21st-century use

CB has lost much of its original appeal due to development of mobile phones, the internet and the Family Radio Service. Changing radio propagation for long-distance communications due to the 11–year sunspot cycle is a factor at these frequencies. In addition, CB may have become a victim of its own popularity; with millions of users on a finite number of frequencies during the mid-to-late 1970s and early 1980s, channels often were noisy and communication difficult, which reduced interest among hobbyists. Business users (such as tow-truck operators, plumbers, and electricians) moved to the VHF and UHF business band frequencies. The business band requires an FCC license, and usually results in an assignment to a single frequency. The advantages of fewer users sharing a frequency, greater authorized output power, clarity of FM transmission, lack of interference by distant stations due to skip propagation, and consistent communications made the VHF (Very High Frequency) radio an attractive alternative to the overcrowded CB channels.

With these factors in play, CB radio has once again gained popularity in recent years, an uptick not seen since the 90's. Manufacturers report an increase in sales, while social media sites like YouTube show a growing popularity in CB radio content, mainly as a hobby. The technology has also given way to more compact CB radios with far more features afforded in older models.^{[citation needed]}

The FCC restricts channel 9 to emergency communications and roadside assistance.^[16] Most highway travelers monitor channel 19. Truck drivers still use CB, which is an effective means of obtaining information about road construction, accidents and police speed traps.

Australia

History

Before CB was authorized in Australia, hand-held 27-MHz "walkie-talkies" were available, which used several frequencies between the present CB channels, such as 27.240 MHz.^[17][18] By the mid-1970s, hobbyists were experimenting with handheld radios and unauthorized 23 channel American CB radios. At that time in Australia, licensed ham operators and Emergency Services still used the 11 meter band^[19] which was not yet available for CB use. Multiple CB clubs had formed by this time, which assigned call signs to members, exchanged QSL cards, and lobbied for the legalisation of CB. In late 1977, having legalised Australian CB and allowed the import / sale of American and Japanese 23 channel sets, the Federal Government drafted new interim regulations for Australian 18 channel transceivers. The new RB249 regulations came into effect on January 1, 1978, and the last official registration date for 23 channel sets was January 31, 1978. After this date, use of unregistered 23 channel CB sets was deemed illegal and unlicensed sets were no longer eligible to be licensed. The 18 channel band plan used 16 channels of the 23 channel CB radios plus 2 extra channels at 27.095 and 27.195 MHz, to make up the 18 channels. The original channels 1, 2, 3, 4, 10, 21 and 23 were deleted from the 18 channel band plan. So channel 1 on an 18 channel was actually channel 5 on a 23 channel radio. These roughly corresponded to the present channels 5–22, except for the two unique frequencies that are known as 11A (Channel 7 on an 18 channel Australian CB) and 19A (Channel 16 on an 18 channel Australian CB) or remote control frequencies but are no longer part of the Australian 27 MHz CB band since 40 Channels were introduced.^[20] On January 1, 1982, the American 40 channel band plan was adopted.

From the outset, the government attempted to regulate CB radio with license fees and call signs, but eventually they abandoned this approach. Enthusiasts rushed for licences when the doors opened at post offices around Australia in mid-1977 and by the end of the first quarter of 1978 an estimated 200,000 licences were issued (Australia's Population in 1978 was 14.36 million). The regulations called for one licence per CB radio. The price for a licence in 1977 was AU$25 per year (In mid 1977 the Australian Dollar exchange rate was AU$0.90 to US$1.00), a not insubstantial amount for the average Australian wage-earner. Australian CB radio uses AM, USB, and LSB modes (no FM) on 27 MHz, allowed output power being 4 Watts AM and 12 Watts SSB. When UHF CB was first legalised the 27 MHz CB Band was intended to be closed to Australian CBers in 1982 and only the 477 MHz UHF band was to continue, however this did not eventuate. The first 477 MHz CB radio in 1977 was designed and made in Australia by Philips TMC and was a 40 channel CB called the FM320.

Community

The first CB club in Australia was the Charlie Brown Touring Car Club (CBTCC),^[21] which formed in Morwell, Victoria in 1967 and consisted mainly of four-wheel drive enthusiasts. The club used the prefix "GL" (for Gippsland), since "CB" could not be used.^[22] After July 1, 1977, the club changed its name to Citizens Band Two Way Communication Club (CBTCC).^{[citation needed]} Other early clubs were "LV" (Latrobe Valley) and "WB" (named after Wayne Britain). Members of these clubs are still active, and have also become amateur radio operators. Other Australian cities which became CB radio "hotspots" were Seymour, Benalla, Holbrook and Gundagai, all located on the busy Hume Highway between Melbourne and Sydney. Other regional cities such as Bendigo, Mildura, Mount Gambier and Port Augusta, developed lively, colourful CB radio communities.

Competing technologies

With the introduction of UHF CB radios in 1977, many operators used both UHF and HF radios and formed groups to own and operate local FM repeaters. Members of the CBTCC formed what became known as Australian Citizens Radio Movement (ACRM) in the early 1970s; this organization became the voice for legalization of CB radio throughout Australia. After peaking in the 1970s and early 1980s, the use of 27 MHz CB in Australia has fallen dramatically due to the introduction of 477 MHz UHF CB (with FM and repeaters) and the proliferation of cheap, compact handheld UHF transceivers. Technology such as mobile telephones and the internet have provided people with other choices for communications. The Australian government has changed the allocation of channels available for UHF CB Radio from 40 to 80, and doubled the number of repeater channels from 8 to 16.^[23]

27 MHz marine radio

Source:^[24] Several channels are allocated for maritime use in Australia. Australia also permits the use of marine VHF radio. 27 MHz radios have the advantage of not requiring a certificate of proficiency to use,^[25] however they may not be monitored by rescue organisations or larger vessels. VHF radios are recommended by state agencies, such as Marine Safety Victoria and Marine Rescue NSW.^[26][27]

Canada

In Canada, the General Radio Service uses the identical frequencies and modes as the United States citizens band, and no special provisions are required for either Canadians or Americans using CB gear while traveling across the border. The General Radio Service was authorized in 1962. Initially, CB channels 1–3 remained allocated to amateur radio and channel 23 was used by paging services. American CB licensees were initially required to apply for a temporary license to operate in Canada.^[28] In April 1977, the service was expanded to the same 40 channels as the American service.^[29]

Indonesia

In Indonesia, CB radios were first introduced about 1977 when some transceivers were imported illegally from Australia, Japan and the United States. The dates are hard to confirm accurately, but early use was known around large cities such as Jakarta, Bandung, Yogyakarta, Surabaya and Medan. The Indonesian government legalized CB on 6 October 1980 with a decision by the Minister of Communications, the "Ministerial Decree on the Licensing for the Operation of Inter-Citizens Radio Communication". Because many people were already using 40 channel radios prior to legalization, the American band plan (with AM and SSB) was adopted; a VHF band was added in 1994, along with allowing use of the Australian UHF CB channel plan at 476-477 MHz On 10 November 1980, the Indonesian Directorate General of Posts and Telecommunications issued another decree establishing RAPI (Radio Antar Penduduk Indonesia) as the official citizens band radio organization in Indonesia.^[30]

Malaysia

In Malaysia, citizens band radios became legal when the "Notification of Issuance Of Class Assignments" by Communication and Multimedia Malaysia was published on 1 April 2000. Under this class assignment, a CB radio is classified as a "Personal Radio Service device". The frequency band is HF, 26.9650 MHz to 27.4050 MHz (40 channels), power output is 4 watts for AM and FM and 12 watts PEP for SSB. Channel 9 is reserved for emergencies, and channel 11 is a calling channel. On UHF 477 MHz, citizens band PRS radio devices are allowed 5 watts power output on FM on 39 assigned channels spaced at 12.5 kHz intervals from 477.0125 to 477.4875 MHz. Channel 9 is reserved for emergencies, and channel 11 for calling. A short-range simplex radio communications service for recreational use is from 477.5250 to 477.9875 MHz FM mode with 38 channels and a power output of 500 mW. A CB radio or Personal Radio Service Device under Class Assignment does not need an individual license to operate in Malaysia if it adheres to the rules of the Warta Kerajaan Malaysia^[31]

On 1 April 2010 the MCMC (Malaysian Communications and Multimedia Commission) released a new regulation^[32] and later on 2017.^[33] This includes a new UHF PMR 446 MHz allocation: an eight-channel analog Personal Mobile Radio 446 MHz (Analog PMR446) with frequencies from 446.00625 to 446.09375 MHz (12.5 kHz spacing) FM with 0.5 watt power output, and 16 channels for Digital Personal Mobile Radio 446 MHz (Digital PMR 446). Frequencies for Digital PMR 446 are from 446.103125 to 446.196875 MHz with 6.25 kHz channel spacing in 4FSK mode and a power output of 0.5 watt. An unofficial citizens band radio club in Malaysia is the "Malaysia Boleh Citizen Radio Group", known as "Mike Bravo" (Malaysia Boleh).^[34]

United Kingdom

In the UK, a small but growing number of people were illegally using American CB radios during the late 1970s and early 1980s. The prominence of CB radio grew in Britain partly due to the success of novelty songs like C.W. McCall's "Convoy" and Laurie Lingo & The Dipsticks’ "Convoy GB" in 1976 (both of which were Top 5 hits). By 1980, CB radio was becoming a popular pastime in Britain; as late as the summer of 1981 the British government was still saying that CB would never be legalized on 27 MHz, proposing a UHF service around 860 MHz called "Open Channel" instead. However, in November 1981 (after high-profile public demonstrations) 40 frequencies unique to the UK, known as the 27/81 Bandplan using FM were allocated at 27 MHz plus 20 channels on 934 MHz (934.0125–934.9625 MHz with 50 kHz spacing). CB's inventor, Al Gross, made the ceremonial first legal British CB call from Trafalgar Square in London.

The maximum power allowable on the MPT 1320 27/81 system was 4 watts (in common with the American system), although initially radios were equipped to reduce output power by 10 dB (to 0.4 watts) if the antenna was mounted more than 7 meters (23') above ground level. The power-reduction switch is also useful in reducing TV interference. MPT 1320 also restricted antennas to a maximum length of 1.5 meters (5'), with base loading being the only type permitted for 27 MHz operation. Over the next several years antenna regulations were relaxed, with antenna length increasing to 1.65 meters (5'5") and centre- or top-loading of the main radiating element permitted. On 1 September 1987 the UK added the usual 40 frequencies (26.965–27.405 MHz) used worldwide, for a total of 80 channels at 27 MHz; antenna regulations were further relaxed, and the 934 MHz band was withdrawn in 1998.

CB radio in the UK was deregulated in December 2006 by the regulatory body Ofcom, and CB radio in the UK is now license-free. The old MPT 1320 27/81 band will continue to be available for the foreseeable future. On 27 June 2014, changes were made by Ofcom to allow the use of AM & SSB modes on CB in the UK legally for the first time. The rules regarding non-approved radios and power levels above 4 Watts on AM/FM and 12 Watts on SSB still apply, despite deregulation. Persons using illegal equipment or accessories still risk prosecution, fines or confiscation of equipment, although this is rarely enforced. AM and SSB on the freeband and amplifier use are common among enthusiasts. Packet radio is legal in the UK, although not widely used. Internet gateway stations are also beginning to appear; although illegal on 27 MHz, these units are connected to other CB stations around the world.

Although the use of CB radios in the UK is limited they are still in use, especially with the farming community, truckers, off-roaders and mini-cab services.^[35] The widely used channel for the Young Farmers' Club is channel 11. The normal calling and truckers' channel is channel 19, although many truck organisations and groups use other channels to avoid abuse.

Frequency allocations

CB radio is not a worldwide, standardized radio service. Each country decides if it wants to authorize such a radio service from its domestic frequency authorizations, and what its standards will be; however, similar radio services exist in many countries. Frequencies, power levels and modes (such as frequency modulation (FM), amplitude modulation (AM), and single-sideband modulation (SSB), often vary from country to country; use of foreign equipment may be illegal. However, many countries have adopted the American channels and their associated frequencies, which is generally in AM mode except some higher channels which are sometimes in SSB mode. In September 2021 the FCC approved the use of FM on CB radio.^[36]

Standard channels

The standard channel numbering is harmonized through the FCC (USA) and the CEPT (Europe).^[d][37]

See also channel assignments for CB use in the United States.

* Channels 3, 7, 11, 15, and 19 have adjacent "hidden" channels (see below); channels 23, 24, and 25 are numbered out-of-order for their frequency allocations in the United States.

Intermediate channels

When looking at the FCC/CEPT channel list there are some channels with a spacing of 20 kHz instead of the regular 10 kHz step. These intermediate frequencies are reserved for the Radio Control Radio Service (RCRS).^[e] The RCRS service is commonly used for remote control of model aircraft and boats. It is an unofficial practice to name these channels by their next lower standard channel number along with a suffix "A" (after). For example, channel "11A" is 27.095 MHz, spaced 10 kHz after standard channel 11 (at 27.085 MHz) is used to provide for part of European railroad's Eurobalise radio communication with trains.

SSB use

This section does not cite any sources. Please help improve this section by adding citations to reliable sources. Unsourced material may be challenged and removed. (October 2015) (Learn how and when to remove this template message)

Single-sideband (SSB) operation involves the selection of either the Lower Side Band (LSB) or the Upper Side Band (USB) mode for transmit and receive. SSB radios also have the standard AM mode for communicating with standard CB radio models. With the original 23 CB channels SSB stations commonly used channel 16, to avoid interference to those using AM (SSB stations are authorized to use 12 watts, as opposed to 4 watts for AM stations) and to more easily locate other SSB stations. With the FCC authorization of 40 channels, SSB operation shifted to channels 36–40. Channel 36 (or 38 for LSB) became the unofficial SSB "calling channels" for stations seeking contacts, with the subsequent conversation moving to channels 37–40. CBers with AM-only radios are asked to not use channels 36 through 40. In return, SSB stations stay off the remaining 35 channels so they could be used by AM stations. This agreement provides interference-free operation for all operators by separating the far more powerful SSB stations from the AM stations. This solution also resolves the confusion created by the false advertising that SSB radios have 120 channels compared to only 40 for AM radios.

While a SSB radio has three possible "modes" (AM, LSB, USB) it can operate in, operation is still limited to the same 40 channels. Some manufacturers tried to sell more radios by claiming that with three different modes possible for each channel, it was the equivalent to 120 channels.^{[citation needed]} Reality is far different: Attempting an SSB conversation while an AM conversation is in progress results in jammed communications for everyone. In general, each channel can only support one AM conversation and no others; if no AM conversation is in progress, two SSB conversations can share one channel without interference if one is in LSB and the other in USB mode. For a particular conversation, everyone must be tuned to the same channel and same mode in order to talk with each other. Starting in October 2021 the FCC has approved FM for CB in the US.

Country-specific variations

The European Conference of Postal and Telecommunications Administrations (CEPT) adopted the North American channel assignments, except channel 23, frequency 27.235 MHz; channel 24, frequency 27.245 MHz; and channel 25, frequency 27.255 MHz.^[37] However, legal CB equipment sold in Europe does follow the North American channel designation. Some member countries permit additional modes and frequencies; for example, Germany has 40 additional channels at 26 MHz for a total of 80. The United Kingdom has an additional 40 channels between 27.60125 and 27.99125 MHz, also making 80 channels in total. Before CEPT, most member countries used a subset of the 40 U.S. channels.

In Russia and Poland, the channels are shifted 5 kHz down; for example, channel 30 is 27.300 MHz.^{[citation needed]} Many operators add a switch to change between the "zeroes" (the Russian/Polish channel assignment) and the "fives" (the international/European assignment). Most contemporary radios built for those markets can do "fives" as well as "zeroes" out of the box. Since roughly 2005–2006, Russia and Poland have adopted use of the standard US channel offset as well as the older channel plan, for two overlapping "grids" of channels.

Russia uses an alphanumeric designation for their CB channel plans, because several "grids" or "bands" of 40 channels each are used, along with both AM and FM mode. Russian CB allocations follow the CB band 26.965–27.405 MHz (designated as band C), as well as 26.515–26.955 MHz (designated as band B) and 27.415–27.855 MHz (designated as band D). Some radios refer to the "mid band" (standard CB band) as "band D" which shifts the letters up one (making 26.515–26.955 MHz "band C" and 27.415–27.855 MHz "band E".

For the convenience of users of the grid were marked by letters. Classic is considered the marking when the main range is designated letter "C". The most common description of the channel is considered to be similar to the following: (C9FM or C9EFM or C9EF or 9EF).

In it:

• the first letter («C») is indicated by a grid that contains a set of 40 channels. If the first letter is not specified, it is considered that it is («C»). For example, (C9EF, 9EF)
• hereinafter ("9") – the channel number. Sometimes less than 10 channels are designated 2 digits. For example, (C9EF, C09EF)
• behind it – an optional designation («E») for "European" or mandatory («R») for "Russian" size frequency nets. For example, (C9EF, C9F, C9RF)
• end – the used modulation («FM») or («F»), («AM») or («A»). e.g. (C9EFM, C9EF, C9EAM, C9EA)

An example of correct designations: C9EF, C9EA, C9RF, C9RA

The 25–30 MHz band (including the CB allocations and frequencies above and below the 26.5–27.860 MHz band) is heavily used for taxi cab and other mobile two-way communications systems in Russia, Ukraine and other former USSR country states.

New Zealand and Japan have unique allocations compared to any other country. New Zealand authorizes use of their New Zealand specific 40 channel 26.330–26.770 MHz frequency plan in addition to the "standard" 40 channel 26.965–27.405 MHz frequency plan for a total of 80 HF CB channels. New Zealand has adopted the Australian UHF CB System as well.^[39]

Japan's CB allocation consists of 8 voice and 2 radio control channels with a maximum power output of 500 mW. AM mode is the only mode permitted and antennas must be non-removable and less than 199 cm (78 inches) long. In Japan, the 26–28 MHz range is allocated to fishery radio services and these frequencies are heavily used for marine communications. Japan's "double side band fishery radio" or "DSB Fishery Radio Service" covers 26.760 MHz-26.944 MHz, 27.016 MHz, and 27.524-27.988 MHz. However, frequencies such as 27.005 MHz AM are widely pirated in Japan with very high power transmitters. This causes interference to the authorized low-power 1 Watt DSB (1 Watt AM) fishery radio service. Instead of 26–27 MHz, Japan has authorized several UHF FM CB-type personal radio services in the 348 MHz, 420–422 MHz and 903–904 MHz bands.

1. 26.968 MHz – Japanese CB Channel 1
2. 26.976 MHz – Japanese CB Channel 2
3. 27.040 MHz – Japanese CB Channel 3
4. 27.080 MHz – Japanese CB Channel 4
5. 27.088 MHz – Japanese CB Channel 5
6. 27.112 MHz – Japanese CB Channel 6
7. 27.120 MHz – Japanese CB Channel 7
8. 27.144 MHz – Japanese CB Channel 8 – Calling Channel

1. 27.048 MHz – Japanese Remote Control R/C Frequency
2. 27.136 MHz – Japanese Remote Control R/C Frequency
3. 27.152 MHz – Japanese Remote Control R/C Frequency

Indonesia has the usual 40 channels at 27 MHz, plus a unique 60-channel allocation from 142.050 to 143.525 MHz.^[40]

In Brazil, CB channels were upgraded from 23 to 60 channels starting in 1979 and again in 1980 to 80 channels ^[pt] (from 26.965 MHz to 27.855 MHz).

CB Radio Channels (ANATEL)

Channel	Frequency	Channel	Frequency
1	26.965	41	27.415
2	26.975	42	27.425
3	26.985	43	27.435
4	27.005	44	27.455
5	27.015	45 Zdroj:https://en.wikipedia.org?pojem=Citizens_band_radio >Text je dostupný pod licencí Creative Commons Uveďte autora – Zachovejte licenci, případně za dalších podmínek. Podrobnosti naleznete na stránce Podmínky užití. Zdroj: Wikipedia.org - čítajte viac o Citizens band radio Navigace: Módní doplňky > Šperkařství Šperky Chytré hodinky Galanterie Hodinářské firmy Hodinky Hodiny Módní doplňky Minerály Pokrývky hlavy Sklářství Zlatníci Zlatnictví Příbuzné výrazy : Řetízek (ozdoba) Šátek Beadweaving Bižuterie Bolo Dřevěný motýlek Deštník Digitálky Fiží Galanterie Hodinky Kšandy Kapesník Korálek Kravata Lanyard Modista Motýlek (oděvní doplněk) Odznak Pléd Placka (odznak) Rukávník Spona na kravatu Sponka do vlasů Tabulky (kolárek) Vějíř Text je dostupný za podmienok Creative Commons Attribution/Share-Alike License 3.0 Unported; prípadne za ďalších podmienok. Podrobnejšie informácie nájdete na stránke Podmienky použitia. Copyright.sk © 2024