Over time, several countries have created similar radio services, with varying requirements for licensing and differing technical standards. While they may be known by other names, such as General Radio Service in Canada, they often use similar frequencies (26 to 28 MHz), and have similar uses, and similar difficulties with antennas and propagation. Licenses may be required, but eligibility is generally simple.
Some countries have personal radio services in the UHF band, such as the European PMR446 and the Australian UHF CB.
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 models, family communications, individual businesses). In 1948, the original "Class D" CB Radios were to be operated on the 460 MHz–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. Al Gross, inventor of the walkie-talkie, started Citizen's Radio Corp. in the late 1940s to merchandise Class B handhelds for the general public.
Ultra-high frequency, or UHF, radios, at the time, were neither practical nor affordable for the average consumer. In 1958, the Class D CB service was moved to 27 MHz, and this band became what is popularly known as CB. There were only 23 channels at the time; the first 22 were taken from what used to be an Amateur 11-meter band, while 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 regulated the Class D CB service, on the 27 MHz band, as of the 1970s.
Most of the 460 MHz–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, 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.
In the 1960s, the service was popular with small trade businesses (e.g., electricians, plumbers, carpenters), as well as truck drivers and radio hobbyists. By the late 60s the advancement of solid-state electronics allowed the weight, size, and cost of the radios to decrease, giving the general public access to a communications medium that had previously been only available to specialists. Many CB clubs were formed, and a special CB slang language evolved, used alongside 10-codes similar to those used in the emergency services.
CB Radio today
CB was once the only practical two-way radio system for the individual consumer, and as such served several distinct types of users such as truck drivers, radio hobbyists, and those who needed a short-range radio for particular tasks. While some of these users have moved on to other radio services, CB is still a popular hobby in many countries.
The 27-MHz-frequencies used by CB, which require a long aerial antenna and tend to propagate poorly indoors, tend to discourage use of handheld radios. Many consumer users of handheld radios (e.g. family use, hunters, hikers) have moved on to 49 MHz and then to the UHF Family Radio Service, while many who need a simple radio for professional use (e.g. tradesmen) have moved on to "dot-color" business radios.
On the other hand, CB is still popular among long-haul truck drivers to communicate directions, traffic problems, and other things of importance. Truckers are known to tune to the unofficial "travelers channel," which is channel 19 (Australia it is channel 8 - 27.055 MHz and UHF ch. 40 - 477.400 MHz; in Russia it is channel 15 in AM modulation). This has long been the case in the United States, but less so in Europe where until recently conflicting regulations made it impossible for the same radio to be used across Europe. As a result, CB in Europe became more associated with hobbyists than with truckers.
Legitimate, short-range use of CB radio is sometimes made difficult by users of 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.
The maximum legal CB power output level in the U.S. is four watts for AM and 12 watts (peak envelope power or "PEP") for SSB, as measured at the antenna connection on the back of the radio. However, illegal external linear amplifiers are frequently used. In the 1970s the FCC banned the sale of linear amplifiers capable of operation from 24 to 35 MHz to discourage their use on the CB band, though the use of high power amplifiers by lawless pirate operators continued. Late in 2006 the FCC amended the regulation to only exclude 26 to 28 MHz. Extremely lax enforcement of these regulations by the FCC has led to manufacturers of illegal linear amplifiers openly advertising their products for sale, and many CB dealers carry these and other amplifiers in their product lines and include them in catalogs.
