Citizens Band radio

Citizens Band radio. A system of short-distance, two-way radio communication for personal and business use on a set of 40 channels within the 27 MHz band. Established by the Federal Communications Commission in the United States, it became widely popular in the 1970s, particularly among truck drivers and hobbyists. Its use requires no individual license in many countries, operating under specific technical and operational rules to minimize interference.

History

The service was created in 1945 by the Federal Communications Commission, originally as a regulated Class-D service for citizens' personal communication. Early growth was slow until the 1973 oil crisis and the subsequent nationwide 55 mph speed limit increased its utility among truckers for coordinating travel and avoiding law enforcement. This period saw a dramatic rise in popularity, with iconic models like the Cobra 29 and units from Uniden becoming commonplace. The craze peaked in the mid-to-late 1970s, inspiring songs like C.W. McCall's "Convoy" and films such as Sam Peckinpah's "Convoy". While usage declined with the advent of mobile phones and the internet, it remains in use for local coordination, notably during emergencies and in rural areas.

Technical details

Operating in the HF band at 27 MHz, specifically from 26.965 MHz to 27.405 MHz, the system uses amplitude modulation for voice communication, though some regions permit single-sideband modulation for greater range. Standard equipment is limited by regulation to a maximum output of 4 watts for AM and 12 watts PEP for SSB. Antennas are typically vertically polarized whip antennas, with performance heavily dependent on proper installation and ground plane design. The wavelength of approximately 11 meters means propagation can be affected by ionospheric conditions, occasionally allowing "skip" communication over hundreds of miles, which is often considered illegal interference to local communications.

Operation and use

Users communicate on 40 shared channels, with certain channels having established informal purposes; for example, Channel 19 is widely recognized as the primary trucking and travel channel in North America. Basic protocols include listening before transmitting and using standardized "10-code" signals, though plain language is increasingly common. Key applications include communication between truckers on interstate highways, coordination at construction sites, among off-roading enthusiasts in areas like the Moab desert, and by small businesses. It also serves as an important, simple backup during disasters when other networks like the cellular network fail, as seen during events like Hurricane Katrina.

Legal status and regulation

In the United States, the Federal Communications Commission regulates the service under Part 95 of its rules, requiring no individual license but mandating compliance with technical standards. Similar regulatory bodies govern it elsewhere, such as Ofcom in the United Kingdom, the ACMA in Australia, and Innovation, Science and Economic Development Canada. Key restrictions universally prohibit its use for obscenity, broadcasting music, or operating with excessive power. While once plagued by interference from illegally amplified "linear amplifiers," enforcement and the decline in use have mitigated this issue. The International Telecommunication Union provides a framework, but specific channel allocations and power limits can vary significantly between member nations like Germany and Japan.

Cultural impact

The medium had a profound effect on 1970s popular culture, creating a unique lexicon of "CB slang" like "10-4," "breaker breaker," and "Smokey Bear" that entered the mainstream. It was celebrated in country music through hits by C.W. McCall and The Allman Brothers Band, and in film with "Convoy" and "The Dukes of Hazzard". The phenomenon fostered a sense of community and real-time information sharing on the open road, predating modern social networks. Its legacy persists in online forums dedicated to the hobby and in its enduring utility in areas with poor cellular coverage, maintaining a niche but loyal following.

Category:Radio communications