Citizens' band radio

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Image:CBRadioKracoJuly82004A.jpg Citizens' Band radio (CB) is, in the United States, a system of short distance radio communication between individuals on a selection of 40 channels within the single 27 MHz (11 meter) band. The CB radio service should not be confused with FRS, GMRS or amateur radio. CB does not (in most countries) require a license and unlike amateur radio, CB may be used for commercial communication. Similar personal radio services exist in other countries, with varying requirements for licencing and differing technical standards.

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Scope

The Citizens' Band radio service in the United States is one of several personal radio services regulated by the FCC. These services began in 1945 to permit citizens a short-distance radio band for personal communication (e.g. radio controlled models, family communications, individual businesses). Originally CB was located in the 460-470 MHz UHF band. There were two classes of CB, A and B. Class B radios had simpler technical requirements but were limited to a smaller range of frequencies.

At the time, the technology wasnt advanced enough to make a UHF radio practical for the average consumer. So, in 1958 the Class D CB service was opened at 27 MHz and this is what is popularly known as CB. Previously, this was a government band (primary allocation to US Forest service, military, etc.) with a secondary allocation for the amateur radio service.

Most of the 460-470 MHz band was reassigned for business and public safety uses, but Class A CB is the ancestor of the present General Mobile Radio Service GMRS. Class B, in the same vein, 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 made in 1973 to create a Class E CB service at 220 MHz, but this was opposed by amateur radio organizations and others. There are several other classes of personal radio services for specialized purposes such as remote control devices.

While parts of this article are specific to the United States, several countries have similar radio services. While they may be known by other names, they often use similar frequencies (26 to 28 MHz), and have similar uses. Licenses may or may not be required but eligibility is generally simple.

On the other hand, some foreign personal radio services, such as the European PMR446 and the Austrialian UHF CB are more similar to the American FRS or GMRS services than the CB service, and so are not covered in this article.

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History

In the 1960s the service was popular for small trade businesses (e.g. electricians, plumbers, carpenters) and transportation services (e.g. taxi and trucking firms). "10 codes" originally used in the public service (e.g. police, fire, ambulance) and land mobile service were used for short acknowledgements. With the advancement of solid-state technology (transistors replacing tubes) in the 1970s, the weight, size and cost of the radios decreased. US truckers were at the head of the boom. Many CB clubs were formed and a special CB slang language evolved. The prominent use of CB radios in mid- and late-1970s films (see list below), television shows such as The Dukes of Hazzard (debuted 1979), and in popular novelty songs such as C.W. McCall's "Convoy" (1976) helped to establish the radios as a nationwide craze in the mid-1970s.

Originally CB did require a license and the use of a call sign but when the CB craze was at its peak, many people ignored this requirement and used made up nicknames or "handles". The use of handles instead of call signs is related to the common practice of using the radios to warn other drivers of speed traps during the time when the United States dropped the national speed limit to 55 mph (90 km/h) beginning in 1974 in response to the 1973 hike in oil prices. The FCC recommended the use of ten-codes and these were used, often in a shortened form, but also many slang terms were developed.

The low cost and simple operation of CB equipment gave access to a communications medium that was previously only available to specialists. The "boom" in CB usage in the 1970s bears several similarities to the advent of the Internet in the 1990s. The many restrictions on the authorized use of CB radio led to widespread disregard of the regulations, most notably in antenna height, distance restriction for communications, licensing and the use of call signs, and allowable transmitter power. Eventually the license requirement was dropped entirely.

The early CB radios sold for mobile use in the US had no more than 23 channels, controlled by plug-in quartz crystals. Almost all were AM only, although single sideband was also allowed. In 1977, an additional 17 channels were added for a total of 40 channels, to relieve some of the overcrowding on the original 23 channels. Channel 9 was reserved for emergency use. Channel 19 became the most popular channel, especially among truck drivers.

In 1973, various groups petitioned the FCC for an allocation of frequencies near 220 MHz for a new "Class E" Citizen's Band service. This was opposed by amateur radio organizations as well as other government agencies and commercial users who desired this allocation for their own usage. While the "Class E" initiative was not successful in the 1970s, the Reagan Administration’s sponsored some of these requirements for the development of the Family Radio Service, General Mobile Radio Service and Multi-Use Radio Service. These services fulfilled a majority of the requirements (e.g. eliminate some of the interference and skip that existed on the shortwave frequencies) proposed by the petitioners in 1973. Today these radios are quiet, affordable and readily accessible.

Throughout the 1970s and early 1980s a phenomenon was developing over the CB radio. Similar to the Internet chat rooms a quarter century later, the CB allowed people to get to know one another in a quasi-anonymous manner. Many movies and stories about CBers and the culture on-the-air developed.

In more recent years CB has lost much of its original appeal due to the advancement of technologies and changing values. Some of this rapid development includes: mobile phones, the Internet, and Family Radio Service. The changing radio wave propagation for long-distance communications, due to the 11 year Sunspot cycle is always a factor for these frequencies. Broadband over Power Lines (BPL) initiatves advocated by EarthLink and some power companies for Internet access offer a new challenge to CB. Because power lines are not designed to prevent radiation of RF energy (no shielding like coaxial cables), BPL represents a potential significant interference source for all radio services using BPL frequency ranges - which includes the Citizens Band 27 MHz allocation.

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CB Radio today

CB is still a popular hobby in many countries though its utility as a method of communication among the general public has diminished, due to developments such as mobile phones. CB radio is still a near-universal method of communication among semi truck drivers in America and also remains very popular in rural areas with farmers and hunters, plus sometimes even acting as a sort of "party line" phone system in deep-rural areas too far in the boonies to have phone lines. Commercial drivers use CB to communicate to other truck drivers directions, traffic problems, and other things of importance. Though any channel (except Channel 9, reserved for emergency use) can be used, Channel 19 remains the most popular among truck drivers.

Legitimate, short-range use of CB radio is sometimes made difficult by uncooperative users or illegal high-power transmitters, which are capable of being heard hundreds of miles (km) away. In the United States, the vast number of users and the low financing of the regulatory body mean that the regulations are only actively enforced against the most severe interfering stations, which makes legitimate operations on the Citizen's band unreliable. Other services, such as Multi-Use Radio Service in the VHF band or FRS and GMRS in the UHF band, exist now to provide the reliable short-range communication service originally envisioned for the Citizen's Band.

The maximum legal CB power output level is four watts for AM and 12 watts (peak envelope power or "PEP") for single side band, as measured at the antenna connection on the back of the radio. More powerful external "linear" amplifiers are commonly and illegally used.

Citizens' Band radios in the United States use frequencies near 27 MHz. During periods of peak sunspot activity, even low-powered transmitters can sometimes be heard for hundreds or even thousands of miles. This "skip" activity, in which signals which bounce off the ionosphere, contributes to interference on CB frequencies. Working "skip" is illegal in the United States, since it contradicts the short-range intended use of the service, though the regulation is widely ignored.

Many radio hobbyists operate illegitimately in the so-called "free band", using either Citizens' Band equipment that has been modified for extended frequency range and higher power, or else amateur radio equipment operated outside the assigned amateur 10 meter band. Such operations are not part of the legally authorized Citizen's Band service and should not be called "CB". Out-of-band operations may interfere with licenced, public safety, commercial, or military users of these frequencies. Illegal transmitters may not meet good engineering practice for harmonic distortion or "splatter", and resulting interference to licenced radio spectrum users will often attract the attention of regulating authorities.

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CB Usage in the United States

Image:CBRadioAntennaJuly2004A.jpg In the United States Citizens' Band (CB) radio service is intended to be a private two-way voice communication service for use in personal and business activities of the general public. Its communications range is from one to five miles. The Citizens' Band radio services are described in part 95 of the Federal Communications Commission's (FCC) and is defined as a personal radio service.

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Eligibility

There are no age, citizenship or license requirements to operate a CB radio in the United States. You may operate on any of the authorized 40 CB channels, however channel 9 is used only for emergency communications or for traveler assistance. Usage of all channels is on a shared basis. Foreign governments and their representatives are not eligible to operate a citizens' band radio station within the United States.

You may operate your station anywhere within the United States, its territories and possessions. You may also operate your US station anywhere in the world except within the territorial limits of areas where radio services are regulated by another agency; such as the United States Department of Defense or of any foreign government.

You must use an FCC certified transmitter. No modifications are allowed to your equipment. Equipment output power is limited to 4 watts for AM transmitters and 12 watts PEP (peak envelope power) for single sideband (SSB) transmitters. There are no restrictions on size or type of antennas, except the antenna must not be more than 20 feet above the highest point of the structure it is mounted to and may not be more than 60 feet above the ground.

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Channel Assignments

To simplify selection of an operating frequency, the Citizens' Band radio spectrum is divided into 40 numbered radio frequency channels from 26.965 to 27.405 MHz, with channels generally spaced 10 kHz apart. Channel numbers are not strictly sequential with frequency; there are gaps for frequencies used by radio-controlled devices.

Furthermore, there is a gap between Channel 22 and Channel 23 (which was later filled by Channels 24 and 25) for historical reasons. Before CB was in existence, there was an Amateur 11-meter band from 26.96 to 27.23 MHz, and a frequency for radio-controlled devices at 27.255 MHz. The 11-meter band became CB Channels 1 to 22, and the radio control frequency was shared with Channel 23.

In Europe, the CEPT adopted the North American channel assignments, except that FM is used instead of AM. Some member countries permit additional modes and frequencies.

Before CEPT, most of the member countries used some subset of the 40 USA channels. The United Kingdom, on the other hand, originally had 40 unique 27 Mhz channels, known as the 27/81 Bandplan. See CB radio in the United Kingdom. With the CEPT channels added, the UK now has 80 channels. Germany also has 40 unique channels for a total of 80.

Australia now has the 40 North American channels, though previously it had only approved the use of the first 22 channels. On the other hand, New Zealand and Japan have unique allocations that dont correspond to any other country's.

The frequencies for the 40 North American/CEPT channels are as follows: 

Channel     Frequency
 
Channel 01   26.965 MHz
Channel 02   26.975 MHz
Channel 03   26.985 MHz
 
Channel 04   27.005 MHz
Channel 05   27.015 MHz
Channel 06   27.025 MHz
Channel 07   27.035 MHz
 
Channel 08   27.055 MHz
Channel 09   27.065 MHz  (emergency channel)
Channel 10   27.075 MHz
Channel 11   27.085 MHz  (unofficial general calling channel)
 
Channel 12   27.105 MHz
Channel 13   27.115 MHz
Channel 14   27.125 MHz
Channel 15   27.135 MHz
 
Channel 16   27.155 MHz
Channel 17   27.165 MHz  (unofficial traffic report channel)
Channel 18   27.175 MHz
Channel 19   27.185 MHz  (unofficial trucker's channel)
 
Channel 20   27.205 MHz
Channel 21   27.215 MHz
Channel 22   27.225 MHz
Channel 23   27.255 MHz
Channel 24   27.235 MHz
Channel 25   27.245 MHz
Channel 26   27.265 MHz
Channel 27   27.275 MHz
Channel 28   27.285 MHz
Channel 29   27.295 MHz
Channel 30   27.305 MHz
Channel 31   27.315 MHz
Channel 32   27.325 MHz
Channel 33   27.335 MHz
Channel 34   27.345 MHz
Channel 35   27.355 MHz
Channel 36   27.365 MHz
Channel 37   27.375 MHz
Channel 38   27.385 MHz  (lsb, national calling frequency)
Channel 39   27.395 MHz
Channel 40   27.405 MHz

The frequency allocation list is supplied by the FCC (Federal Communications Commission) from Part 95 - Subpart D - Rules for CB Service Citizens Band (CB) Radio Service.

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Remote Control

Remote control channels
3A 26.995 MHz
7A 27.045 MHz
11A 27.095 MHz
15A 27.145 MHz
19A 27.195 MHz

There is also a Class C Citizens Band service for radio-controlled devices; no voice transmissions are permitted. It has six channels in the 27 MHz band. Five are unused 10 kHz assignments between channels 3/4, 7/8, 11/12, 15/16 and 19/20, and the sixth is shared with Channel 23. Radio control transmitters may use up to 4 watts on the first five channels and 25 watts on the last, 27.255 MHz. Some in-house paging systems, and car alarms with a paging feature, also use these frequencies, especially 27.255 where more power is permitted.

The 27 Mhz Class C channels are not officially numbered. R/C enthusiasts usually designate them by color, and fly different-colored flags from the antenna to show who is on which channel. On the other hand, some CB operators illegally use these channels for voice communications, and usually refer to them by the closest voice channel below them, ex. "3A", "7A", etc.

Because of interference from CB radios, legal or otherwise, the noise level, and the limited number of channels, most "serious" hobby remote control vehicles operate on other bands. Interference is especially important for model aircraft where it presents a safety issue.

The Class C service has 50 channels just for model aircraft in the 72.0-73.0 MHz range, and 30 more channels for surface models such as cars and boats in the 75.4-76.0 MHz range. 0.75 watts is allowed on these numbered channels. Licensed amateur radio operators also have their own R/C channels around 50 and 53 MHz.

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Part 15 and ISM Devices

Most toy R/C cars operate on the 27 MHz R/C channels, especially 27.145 MHz. But most of these devices run far less than 4 watts and do not operate under the Class C CB service. Instead, they operate under the FCC's Part 15 rules, which allows a wide variety of low powered devices to use the frequencies from 26.96 to 27.28 MHz, which covers CB Channels 1 through 27.

Some other of these toys operate on the 49 MHz Part 15 channels, and often a pair of cars will be sold with one on 27.145 and one on 49.860 to avoid interference. This allows less selective, and therefore less expensive, receivers to be used than if they were using channels in the same band.

In the days when CB required a license, some low-powered or toy walkie-talkies were exempt because they operated within Part 15. More recently in the 1990's, low-powered handhelds using FM voice on the radio-control channels were also sold to operate legally under Part 15.

Another class of devices operating in the 27 MHz band are ISM ( Industial, Scientific and Medical ) devices regulated by the FCC's Part 18 rules. Induction welding of plastics, and some types of diathermy machines commonly operate in this range. These devices are centered around 27.12 MHz with a tolerance of ±163 kHz, that is, 26.957 to 27.283 MHz.

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Shooting Skip

Although CB radio was only intended to be a short range communications service, the frequencies on which it operates have some very interesting propagation characteristics. All frequencies in the HF spectrum (3–30 MHz) are able to be refracted by the existence of highly charged particles in the ionosphere. This bouncing of a signal off the ionosphere is called skywave propagation or "shooting skip". With the ability to shoot skip, CBers have been able to communicate thousands of miles, sometimes around the world. The ability of the ionosphere to refract signals back to work is caused by the sun and the amount of ionization possible is related to the 11-year sunspot cycle. In times of high sunspot activity the band can remain "open" to much of the world for long periods of time. In years of low sunspot activity it may not be possible to shoot skip at all.

It is recorded that, before CB radio arose, the Afrika Korps in North Africa in WWII used 27 MHz for battlefield communications, thinking that it could only be heard locally; but skip was strong at the time, and the messages were routinely monitored in the United Kingdom.

Finally, It should be noted that under Part 95, Subpart D of the FCC rules it is illegal to engage in, or attempt to engage in communications with any station more than 250 kilometers (155.3 miles) from your location, thereby making it practically impossible for CB operators who wish to shoot skip to remain in compliance with FCC regulations. The intent behind this restriction is typically regarded as an effort to keep CB as an inherently local service.

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Freebanding and Export Radios

Operation on frequencies above ("uppers") or below ("lowers") the established citizens band is referred to as "freebanding" or "outbanding". Many perceive these frequencies just below the CB band, or between the CB band and the amateur radio 10-meter band to be quiet and under-utilized.

This is done with modified CB equipment, modified 10-meter ham radios, foreign CB radios that may offer different channels, or with radios which are purportedly sold for export.

Unlike modified amateur radios which are frequency-agile, export CB's are channelized. Frequency selection on these "export radios", however, resembles that of modified CB's more than any foreign frequency plan. They typically have a knob and display that reads up to channel 40, but include an extra "band" selector that shifts all 40 channels above or below the band, plus a "+10 KHz" button to reach the model control 'A' channels. These radios may have 6 or even 12 bands, establishing a set of quasi-CB channels on all sorts of unauthorized frequencies. The bands are typically lettered, with the normal CB band in the middle.

For example, a freebander with an export radio who wants to use 27.635 Mhz would choose Channel 19 ( 27.185 ) and then shift the radio up one band ( + 0.450 ). The operator may have to do quite a bit of arithmetic to know which frequency he is actually operating on, though more expensive radios include a frequency counter.

Even well-meaning ( but illegal ) operations can end up on frequencies which are very much in use. For instance, Channel 19, 2 bands up, becomes 28.085 MHz, which is in a Morse code-only part of the 10-meter ham band.

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Regulation and Enforcement

Actions against violations of FCC regulations have been minimal in the past. This has often been cited as the reason for many of the problems that have plagued the Citizens' band radio service in the past.

In recent years, the FCC has had a renewed interest in taking enforcement actions against freebanding, the sale and use of illegally modified radios and linear amplifiers. Usually, the FCC will issue a request for information explaining actions found to be in violation of the commissions rules and regulations. Responding in a timely manner to such a request usually results in a "quick and painless" resolution which in most cases does not result in a fine, but merely a cease and desist order. Failure to respond to the commission's letters of inquiry will commonly result in the issuing of a $10,000 fine and in rem seizure of the equipment used, and suspension of licences in other FCC regulated services.

Many actions have been taken in recent years against the so-called freebanders operating illegally between 26 and 30 MHz. This segment includes military, government allocations (26 MHz - 28 MHz) not assigned to the Citizens Band service as well as the Amateur radio 10-meter band (28 - 30 MHz). Actions have also been taken against retailers in the United States for selling linear amplifiers and non-type approved equipment in violation of the commission's rules.

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CB in popular culture

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Famous CBers

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CB in movies

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CB radio in music

Quickly establishing itself as 1976's biggest fad, CB radio appears in several of the year's biggest hits. All of these charted on both the US pop and country music charts that year:

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International use

Similar services exist in other countries around the world (see for example CB radio in the United Kingdom and Australian UHF CB-equivalent). Technical standards, power levels, and frequencies are different so North American CB equipment may not comply with European regulations, and vice versa. Often other radio services will use FM instead of AM or SSB.

A gray market trade in imported CB gear does exist in many countries. In many instances, sale or ownership of foreign-specification CB gear is not illegal, but the actual use of it is. With the FCC's minimal enforcement of its rules regarding CB radio, enthusiasts in the USA often use "export" radios, or possibly European FM CB gear to get away from the overcrowded AM channels. American AM gear has also been exported to Europe.

In Canada, the "General Radio Service" has the identical frequencies and modes as the United States "Citizen's band", and no special provisions are required for either Canadians or Americans using CB gear while travelling across the border.

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See also

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External links

it:CB (radio) ja:市民ラジオ no:Privatradio

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