CB usage in the United States
In the United States, the Citizens' Radio Service, or Citizens' Band (CB), is one of several personal radio services defined by the FCC's Part 95 rules. It is intended to be a two-way voice communication service for use in personal and business activities of the general public, and has a reliable communications range of several miles, though highly dependent on type of radio and antenna.
CB Radio is most frequently used by long-haul truck drivers for everything from relaying information regarding road conditions, the location of speed traps and other travel information, to basic socializing and friendly chatter.
There are no age, citizenship, or license requirements to operate a CB radio in the United States. Operators may use any of the authorized 40 CB channels; however, channel 9 is used only for emergency communications or for traveler assistance. Use of all channels is on a shared basis. However, foreign governments and their representatives are not eligible to use citizens' band radio within the United States.
Operation is permitted anywhere within the United States and its territories or possessions; as well as anywhere in the world except within the territorial limits of areas where radio services are regulated by a foreign government, or another U.S. agency such as the Department of Defense.
Transmitters must be FCC certified and may not be modified, including modifications to increase output power or to transmit on unauthorized frequencies. Output power is limited to 4 watts for AM transmitters and 12 watts peak envelope power for single sideband (SSB) transmitters. The antenna may not be more than 20 feet (6.1 m) above the highest point of the structure it is mounted to, nor more than 60 feet (18.3 m) above the ground.
North American/CEPT frequencies
|CB Channel||Frequency||Typical Use (US)|
|Channel 1||26.965 MHz|
|Channel 2||26.975 MHz|
|Channel 3||26.985 MHz|
|Channel 4||27.005 MHz||4x4 channel|
|Channel 5||27.015 MHz|
|Channel 6||27.025 MHz||many operators using illegal high-power amplifiers|
|Channel 7||27.035 MHz|
|Channel 8||27.055 MHz|
|Channel 9||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||unofficial RV channel|
|Channel 14||27.125 MHz||included crystal on many walkie-talkies|
|Channel 15||27.135 MHz|
|Channel 16||27.155 MHz|
|Channel 17||27.165 MHz||NORTH-SOUTH FREEWAYS TRUCKERS CHANNEL|
|Channel 18||27.175 MHz|
|Channel 19||27.185 MHz||EAST-WEST FREEWAYS TRUCKERS CHANNEL
Notable as being the center frequency of the band, therefore where antennas are most efficient (SWR)
|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||depending on local needs, channels numbered above 30 or 35 are generally used for SSB operation|
|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||unofficial SSB calling channel, LSB mode|
|Channel 39||27.395 MHz|
|Channel 40||27.405 MHz|
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.
Channel 19 is the most commonly used by truck drivers on highways, to the point that some radios even have a dedicated button to bring up channel 19 instantly. In most areas of the U.S., Channel 17 is customarily used on highways running North-South and Channel 19 for highways East-West, and sometimes even for specific roads. Other channels regionally used for this purpose include 10, 17, and 21. Channel 13 is preferred in some areas for marine use and for recreational vehicles.
Several countries reserve a channel for emergency use, for example, channel 9 in the United States. In CB's heyday in the 1970s, channel 9 was monitored by parties who could relay messages to the authorities, or even directly by the authorities themselves. With the popularity of cellular phones, support for Channel 9 as an emergency channel has diminished, though volunteer organizations such as REACT (Radio Emergency Associated Communications Teams), and private individuals still monitor Channel 9 in some (particularly rural) areas.
Among several other services that share the CB frequencies is the 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 as an alternate of the closest voice channel below them (such as 3A, as shown in the table). In CB radios whose channel selector was a multiple-gang rotary switch that presented a binary number to the tuning electronics, it was a common illegal modification to add a toggle switch to modify the low-order bit and thus gain access to intermediate frequencies.
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 MHz.
Part 15 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 R/C 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. However, in 1976, the FCC phased in a shift of these 100 mW devices to the 49 MHz band, with operation on the CB frequencies to cease in 1983. More recently in the 1990s, low-powered handhelds using FM voice on the 27 MHz 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 (Industrial, 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.
Adjacent frequency bands
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[when?], CAP volunteers with crystal-controlled CBs would put this frequency in their radios. Currently VHF military frequencies are more often used, as among other reasons, VHF radios are easier to acquire than crystal-controlled CBs.
|This article needs additional citations for verification. (February 2013)|
||This article contains weasel words: vague phrasing that often accompanies biased or unverifiable information. (February 2013)|
In the past, FCC actions against violations of regulations was minimal. This was often cited as the reason for many of the problems that have plagued[weasel words] the Citizens' Band radio service.
In recent years[when?], the FCC has had a renewed interest in enforcement against "freebanding," the sale and use of illegally modified radios and linear amplifiers.[verification needed] Usually, the FCC issues a notice of apparent liability, a citation of violations of the commission's rules and regulations. If the violator responds in a timely manner to the notice, the resolution usually involves a cease-and-desist order. Failure to respond to the commission may provoke a $10,000 fine, seizure of the equipment used, and suspension of licenses in other FCC-regulated services.[verification needed]
Many actions[vague] have been taken against freebanding operation between 26 and 30 MHz, including those on military and government allocations adjacent to the Citizen's Band, and on the amateur radio 10-meter band (28-29.7 MHz).[verification needed] 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.[verification needed]
- Kneitel, Tom (1988). Tomcat's Big CB Handbook. Commack, NY: CRB Research Books. pp. 203–204. ISBN 0-939780-07-0.
- Chilton Automotive Editorial Department (1977). Chilton's CB Handbook. Radnor, PA: Chilton Book Company. p. 12. ISBN 0-8019-6623-X.
- These Part 15 devices are now regulated by field strength, not transmitter input power.
- Chilton Automotive Editorial Department (1977). Chilton's CB Handbook. Radnor, PA: Chilton Book Company. p. 20. ISBN 0-8019-6623-X.
- Article 5 RR 171 Radio regulations annexed to the International Telecommunication Convention (Atlantic City, 1947)
- Hughes, Gene; Richard Barnett (2000). Police Call, Vol. 1, 2001 edition. Los Angeles: Hollins Radio Data. pp. 277, 384–385, 387. OCLC 46316778.