Citizens' band radio

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, MURS or amateur radio. Similar personal radio services exist in other countries, with varying requirements for licensing and differing technical standards. In many countries, CB does not require a license and unlike amateur radio, it may be used for commercial communication.

Contents 1 Scope 2 History 2.1 Australia 3 CB Radio today 4 CB Usage in the United States 4.1 Eligibility 4.2 Channel Assignments 4.3 Remote Control 4.4 Part 15 and ISM Devices 4.5 Shooting Skip, Skywave 4.6 Freebanding and Export Radios 4.7 Adjacent Radio Services 4.8 Regulation and Enforcement 5 CB Usage Worldwide 6 CB Antennas

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 wasn't 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 Australian UHF CB are more similar to the American FRS or GMRS services than the CB service, and so are not covered in this article.

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 America from the mid-1970s to the early 1980s.

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 and in Britain in the early 1980s 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.

Originally, there were only 23 CB channels in the U.S.; 40-channel radios did not come along until 1977. In the 1960s, channels 1-8 and 15-22 were reserved for "intrastation" communications among units under the same license, while the other channels (9-14 and 23) could be used for "interstation" calls to other licenses.

In the early 1970s, channel 9 became reserved for emergency use. Channel 10 was used for highway communications, and channel 11 was used as a general calling channel. Later, channel 19 became the preferred highway channel in most areas, as it did not have the adjacent-channel interference problems with channel 9.

Until the late 1970s when synthesized radios appeared, CB radios were controlled by plug-in quartz crystals. Almost all were AM only, though there were a few single sideband sets in the early days.

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 early on, 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 Britain, some people were using CB radio illegally in the 1970s, a craze which suddenly peaked in 1980, leading to legalisation on 2 November 1981. However, in the summer of 1981 the British government were still saying that CB would never be legalised on 27 MHz. The government wanted a uhf frequency around 860 MHz named 'Open Channel' instead. Eventually 40 channels at 27 MHz, plus 20 channels on 934 MHz were legalised. Both allocations used frequencies unique to the UK; the 934 MHz allocation was later withdrawn in 1998. CB's inventor Al Gross made the first legal British CB call, from Trafalgar Square, London. CB was so popular in the UK by 1982 that it was featured in a Coronation Street storyline - fame indeed!

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.

Australia

In Australia, Citizens Band radio had its beginnings in the 1960s when small numbers of American branded 1-watt “walkie-talkies” started to become available from a handful of outlets. In those days, households were required to hold licenses to operate a TV set, but no such licenses were available to the general public for the use of 27 MHz band radios.

By the early 1970s CB radio began to gather pace as bigger and better transceivers appeared on the market. Designed for in-car installation, these units began to be sold from well recognized and specialist retail outlets. As the popularity of CB radio grew in cities such as Melbourne and Sydney, the 27.240 MHz calling frequency became congested at times and users were forced to find other less popular channels to have conversations and to organize an ‘eyeball’ (meeting).

By 1974, the transceiver of choice was the American designed Midland 23-channel, 5-watt transceiver with upper and lower single sideband (SSB). The Lafayette and Tandy/Realistic brands were also popular. These higher-powered units, when coupled with high-gain antennas and linear amplifiers, often sent out spurious RF emissions which attracted unwanted attentions. The Federal Postmaster-General (PMG Department) was solely responsible for Australian radio spectrum management and radio licensing since the end of World War 2. For the 27 MHz/11-metre band however, the only persons who could legally operate transceivers were licensed radio amateurs who had passed a technical examination, and most had nothing but contempt for the persons operating illegally on the 11-metre band. A small team of radio inspectors began covert surveillance of the “radio pirates” (as they were known) using the 27 MHz band in major Australian cities. They built a database of regular, or nuisance users, particularly those using the higher-powered transceivers, or those boasting of the use of home made linear amplifiers. Radio inspectors, most of who were licensed radio amateurs, had extraordinary powers in those days and it was not uncommon to hear of or meet CB operators who had been on the receiving end of a visit from overly zealous inspectors with a search warrant. Such visits often resulted in the forced entry of houses and rooms, a confiscation of all equipment, (illegal or otherwise), and a summons to appear in court for various breaches of the ‘wireless telegraphy’ laws and regulations in force at the time. Running battles and cat and mouse-like games developed as radio pirates tried to keep one step ahead of inspectors. Some pirates developed elaborate hiding places in their homes or cars for their equipment. Various State polices forces were mainly ignorant of the illegality of the use of CB radios since it was a Federal jurisdiction issue. CB radios or giveaway antennas were however viewed suspiciously by some individual police who saw them as a means to warn other drivers of speed traps established by the police. Unsure of the legal position, they usually took no further action if they found a CB radio fitted in a car.

By the mid-seventies, a number of CB clubs had developed around Australia including the KT (Kangaroo Territory) Club, the GL Club and Delta Whisky Club, all of whom assigned call-sign numbers to radio pirates interested in ‘joining’ the club. The exchange of QSL cards become popular (like with the licensed radio amateurs), and if atmospheric and sunspot activity was suitable, long-distance ‘skip’ communications could be achieved between pirates thousands of kilometres apart. As the popularity of CB continued to grow, pressure began to be applied to the Federal Government to permit the legal use of the 27 MHz band

The GL Club in the Gippsland region in the State of Victoria was particularly active with representations being made to locally based Federal politicians. In February 1975 an informal but widely CB-advertised convention was held in a hall on the outskirts of the town of Morwell, and a newly formed lobby group known as the Australian Citizens Radio Movement began life. Its primary aim was to get CB radio legalized.

On 1 July 1977, after more than two years of relentless pressure from public lobby groups, interstate truck drivers, rural fire brigades and volunteer emergency service units, the Federal Government finally legalized CB radio on 27 MHz with an initial allocation of 18 channels. Not surprisingly, the radio inspectors who had so zealously attempted to protect the airways prior to this time imposed industrial bans because they opposed the new laws. Hence the initial flood of license applications were slow in being processed. In 1980 a total of 40 channels was approved for 27 MHz band and it was aligned with the 40 channels used in the USA. From the outset, the Government attempted to regulate CB radio with license fees and call-signs etc, but some years later abandoned this approach.

After peaking in the 1970s and early 1980s, the use of 27 MHz CB in Australia has fallen dramatically in the last decade. The later introduction of UHF CB Radio and the proliferation of cheap, compact handheld and portable transceivers have been a part of the reason. But other emerging technologies such as e-mail, IRC chat, mobile phones/SMS, and the Internet have played a role by providing people with many choices of communication.

Over the years there have been repeated attempts by the Federal Department of Communications to close down the 27 MHz band. To date, these attempts have failed in the face of opposition.

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 and Internet chat rooms and IM. 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. Channel 19 is the most commonly used for this purpose, to the point that some radios even have a dedicated button to bring up channel 19. In some areas of the U.S., different channels are customarily used on highways running North-South versus East-West, and sometimes even for specific roads. Other channels regionally used for this purpose include 10, 17, and 21.

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 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", (which is often referred to as 11 meters, similar to how hams refer to their bands by the approximate wavelengths) 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 licensed, 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 licensed radio spectrum users will often attract the attention of regulating authorities.

In its heyday in the 1970s, you were likely to find CB Channel 9 monitored by parties who could relay messages to the authorities, or even directly monitored by the authorities themselves. However, with the popularity of cellular phones, support for Channel 9 as an emergency channel has largely vanished. If you are in dire need of help on the road and your only communications tool is a CB radio, you are much more likely to find help on Channel 19.

CB Usage in the United States

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.

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.

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.

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
 
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
Channel 18   27.175 MHz
Channel 19   27.185 MHz  (unofficial highway channel)
 
Channel 20   27.205 MHz
Channel 21   27.215 MHz
Channel 22   27.225 MHz
Channel 23   27.255 MHz  (Note frequencies not in ascending order}
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.

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 radio-controlled models 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.

Part 15 and ISM Devices

Most toy R/C cars and most wireless keyboards and mice 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 allow 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.

Broadband over Power Lines (BPL) technology uses a wide range of HF frequencies to transmit data, including the CB frequencies. There is some potential for interference, as power lines were never specifically designed to shield radio frequencies. RF leakage from BPL is regulated 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.

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.

Skywave

Skywave is the propagation of radio waves bent (refracted) back to the Earth's surface by the ionosphere. As a result of skywave propagation, a nighttime broadcast signal from a distant AM broadcasting or shortwave radio station (or rarely, a TV station) can sometimes be heard as clearly as local stations. Most long-distance HF radio communication (between 3 and 30 MHz) is a result of skywave propagation. For decades Amateur radio operators, limited to lower transmit power than commercial radio, have taken advantage of skywave for distance or DX communication.

Role of the ionosphere
The ionosphere is a region of the upper atmosphere, where neutral air is ionized by solar photons and cosmic rays. When radio waves reach the ionosphere at a shallow angle, they are partly reflected by the surface. The ionosphere can also be similar to a prism refracting light; different frequencies are "bent" by different amounts.

Much as the surface of the ocean interacts with the wind, the condition of the ionosphere is constantly changing due to interaction with incoming radiation. When signals have "bounced" off this irregular surface, they may fade in and out and have the "phasing", "flanging" or "fluttery" character familiar to listeners of shortwave music broadcasts.

Depending on the transmitting antenna, the signals may reach the ionosphere at a steep angle (vertical incidence) and be reflected almost straight down. Alternately the antenna may "aim" the signal at the horizon; the signal reaches the ionosphere at a shallow angle and returns to earth at a great distance.

Under some conditions, the Earth's surface (ground or water) may reflect the incoming wave back toward the ionosphere again. As a result, like a rock "skipping" across water, the wave may actually "bounce" or "skip" between the earth and ionosphere several times. This phenomenon is known as "skip" or multihop propagation. Signals of only a few watts can sometimes be received thousands of miles away as a result.

Other considerations
Signals with frequencies above about 30 MHz (VHF and UHF for example) are progressively not returned to the Earth's surface, because they penetrate the ionosphere. (This includes most communications with spacecraft and satellites.) Exceptions include rare occasions of E-skip, when FM and TV signals are reflected. Skywave may be disrupted during geomagnetic storms.

Low to mid frequencies below approximately 10 MHz (longer than 30 meters), including broadcasts in the mediumwave and shortwave bands (and to some extent longwave), travel most efficiently by skywave at night. Frequencies above 10 MHz (shorter than 30 meters) travel better during the day. Frequencies lower than 3 kHz have a wavelength longer than the distance between the Earth and the ionosphere. The Maximum usable frequency for skywave propagation is strongly influenced by sunspot number.

Because the lower-altitude layers (the E-layer in particular) of the ionosphere largely disappear at night, the refractive layer of the ionosphere is much higher above the surface at night. This leads to an increase in the "skip" or "hop" distance of the skywave at night.

 

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 American 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 'A' through 'F', with the normal CB band as 'D'.

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. Licensed amateurs typically regard this activity as an intrusion, and have been known to record, locate, and report such transmissions.

Freeband operators have been known to use modified amateur radios that are capable of transmitting on the 11 meter CB band after modification. In newer amateur radios this modification is usually as simple as removing a single part, while in older amateur radios it is often more difficult. Some examples of amateur radios that popularly used on "freeband" are the Kenwood 440, Kenwood 520, and the Yaesu FT-101. However, these are classic examples and today one can hear many different types of amateur radios on 11 meter freeband. It is illegal in the United States to transmit on the 11 meter band with an amateur radio under normal, non-life threatening instances.

Adjacent Radio Services

The Business Radio Service has several channels just above the Citizen's Band, at 27.430, 27.450, 27.470, 27.490, 27.510, and 27.530 MHz.

The federal government has the frequencies from 27.540 up to 28.000. Many civilian agencies use, or used to use, the frequencies 27.575 and 27.585 for low-power use.

The 10 meter ham band runs from 28.000 to 29.700 MHz.

Below the Citizen's Band, the U.S. military has the frequencies from 26.480 to 26.960.

The Civil Air Patrol has 26.620, though it now uses mostly VHF frequencies. Years ago, CAP volunteers with crystal-controlled CBs would put this frequency in their radios. Now, this frequency is all but abandoned as VHF radios are now easier to come by than crystal-controlled CBs.

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 licenses in other FCC regulated services.

Today's actions of illegal CBer's are usually not cared about by the FCC. They will only go after people who disrupt important radiocommunications, or are reported by people who are having trouble with neighbors who have over-powered CB's. It usually interferes with broadcast television.

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.

CB Usage Worldwide

Similar radio services exist in other countries around the world. Frequencies, power levels, and modes ( such as FM, AM and SSB ) may vary from country to country, and usage of foreign equipment may be illegal.

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.

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 at 26 MHz for a total of 80.

In the United Kingdom though CB is virtually devoid of activity, a licence is still required, though may soon be withdrawn, but the UK-only frequencies may themselves be withdrawn in 2010 and reassigned to the Community Audio Distribution System service.

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 don't correspond to any other country's.

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.

Using radios outside their intended market can be dangerous as well as illegal. For example, the British frequencies clash with a radio system used by ambulance services in Ukraine.

CB Antennas

As 27 MHz is a relatively long wavelength for mobile communications, the choice of antenna has a considerable impact on the performance of a CB radio.

One common mobile antenna is a quarter-wave vertical whip. This is roughly nine feet tall and mounted low on the vehicle body, and often has a spring and ball mount.

Where a nine-foot whip would be impractical, shorter antennas include loading coils to make the antenna electrically longer than it actually is. The loading coil may be on the bottom, middle, or top of the antenna, while some antennas are wound in a continuously loaded helix.

Many truckers use two co-phased antennas mounted on their mirrors. This arrangement provides some directivity toward the front and back of the truck, that is, up and down the highway.

Another specialty mobile antenna is the continuously-loaded half-wave antenna. These do not require a ground plane, and are often used on fiberglass vehicles such as snowmobiles or boats.

Handheld CB's often use either a telescoping center-loaded whip, or a continuously-loaded "rubber ducky" antenna.

Base CB antennas may be vertical for omnidirectional coverage, or directional "beam" antennas may be used to direct communications to a particular region.