Citizens' Band (CB) radio is, in many countries, a system of short-distance, simplex radio communications between individuals on a selection of 40 channels within the 27 MHz (11 meter) band. The CB radio service should not be confused with FRS, GMRS, MURS, or amateur ("ham") 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. CB Radio is most commonly used amongst truck drivers and a great deal of slang such as "Bear/Bear Cave" (meaning police officer/police station) and "alligator" (meaning blown tire on the road/side of road) can be heard.
In the US the FCC has a general rule that during an emergency (read to protect life or property) you may utilize any operating mode, any frequency and any power level that you believe will bring assistance. Until then:
- Communications (or attempts to communicate) with stations over 250 km (155.3 miles) away are prohibited.
- Single side band (SSB) transmissions are authorized up to 12 watts Peak Envelope Power (PEP), while AM transmissions are permitted up to four watts carrier power.
- You must use an FCC-certified CB unit in the United States. FCC-certified CB units have an FCC-certified label placed by the manufacturer.
- Users must never talk with another station for more than 5 minutes continuously, and must wait at least one minute before starting another communication.
- You may not raise the power output of your CB unit, attach any type of power amplifier, or modify the unit internally.
Selecting a Radio
In addition to the general rules of selecting a radio you should also look for the following:
- SSB at 12w
- AM has 2 sidebands which contain the exact same information, as well as a carrier. SSB removes the carrier (50% of the energy) and one sideband (25% of the energy) this makes it MUCH more efficient at the same power output. In addition you get 12w of output, 4 times more. This is like having 1600% more transmission ability than you would otherwise have.
- SSB transmissions can "hide" from AM only receivers, you can have twice as many conversations using SSB than you can with AM in the same RF spectrum.
- Selectable power output
- By getting a selectable power output, you can turn the power down when you do not need to reach anyone very far away. This can save batteries, it can also prevent others hearing your transmission that you did not intend.
- removable antenna
- By having a removable antenna you can install a better one when you have the capability. For example if you have a handheld unit, you can use a larger, better radiating one at base camp, and install a field use one when wandering around. A better antenna can easily double your effective radiated power (ERP) and this does not violate the FCC rules to use it now. See homebrew antennas for more information on what you can make that is portable.