Current Use
CB was the only practical two-way radio system for the individual consumer, and served several subsets of users such as truck drivers, radio hobbyists, and those in need of short-range radio communications. While some 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 relatively long aerial and tend to propagate poorly indoors, discourage the use of handheld radios. Many users of handheld radios (families, hunters and hikers) have moved on to 49 MHz and the UHF Family Radio Service; those needing a simple radio for professional use (e.g., tradesmen) have moved on to "dot-color" business radios.
CB is still popular among long-haul truck drivers to communicate directions, traffic problems and other relevant matters. The unofficial "travelers channel" in most of the world is channel 19; in Australia it is channel 8 (27.055 MHz) and UHF channel 40 (477.400 MHz). In Russia it is channel 15 (in addition to traditional "emergency" 9 and "truckers" 19 channels) and in Greece it is channel 13, both AM. These frequencies may have evolved because tuned circuits (particularly antennas) work best in the middle of the band; the frequency for channel 19 (not channel 20) is the center of the 40-channel US band and other things being equal, signals will be transmitted and heard the farthest. Since less standardization exists in Europe, CB there is more associated with hobbyists than with truckers.
Legal (short-range) use of CB radio is sometimes impeded by users of illegal high-power transmitters, which can be heard hundreds of miles away. The other problem with short-range CB use in propagation; during long-range "skip" conditions local signals are inaudible while distant signals boom in as if they were local. In the United States, the number of users and low enforcement financing by the Federal Communications Commission mean that only the worst offenders are sanctioned, which makes legitimate operation on the Citizens' Band unreliable. Most offenders are not caught for interfering with other CB users; often, their self-modified equipment generates harmonics and spurs which cause interference to services outside the Citizens' Band and to consumer equipment.
The maximum legal CB power output level in the U.S. is 4 watts for AM (unmodulated carrier; modulation can be four times the carrier power, or 16 watts PEP) and 12 watts PEP for SSB, as measured at the transmitter antenna connection. However, external linear amplifiers are often used illegally. During 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, although the use of high-power amplifiers continued. Late in 2006, the FCC amended the regulation to exclude only 26 to 28 MHz to facilitate amateur 10-meter operation. Lax enforcement enables manufacturers of illegal linear amplifiers to openly advertise their products; many CB dealers include these amplifiers in their catalogs.
Read more about this topic: Citizens Band Radio
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