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CB - English abbreviation of «Citizens’ Band» -"citizens’ band". This abbreviation is taken for the meaning of “unlicensed”, available to ordinary user in the radio range of 27 MHz. The usage of this range, depending on the country, is minimally regulated by the rules for conducting local communications, or not regulated at all.
Radio facilities of this range look like wearable, portable or stationary radio stations, which, as a rule, differ from radio amateurs’ and professional radio stations by having lower prices, less functions (absence of telegraphic mode, single-sideband modulation, repeater shift, tone and code squelch, trunk modules and etc.), more modest specifications, with less level of impact strength and water proofness.
The usage of CB
Possibilities of using CB communications are very wide. This type of communication facility is quite reliable and available, which helps to connect, for example, store with warehouse, warehouse with transport and so on. CB radio communication can be used at small boats, such as motor boats or yachts. Thereby the range of communication on the water significantly increases.
The most massive use of CB radio communication was found in mobile communication. Radio stations in cars always allow communicating with each other, getting current traffic information, helping to choose a route, also with technical problems and accidents on the road.
The use of handheld CB radio stations is quite problematic, because in the CB range the length of wave is 11 meters, and the length of full quarter-wave antenna is approximately 2, 7 meters. There is a need to shorten CB-handheld antennas geometrically by 10-20 times, what significantly reduces the range of communication.
What is more, foreign portable CB radio set differed from others sufficiently large weight (approximately 500 g), low coefficient of efficiency level of transmission unit during the work on a compact antenna and low efficiency level of amplitude squelch, and as a result economical efficiency and communication range of such radio stations were not high.
According to that almost all such radio stations were removed from the production (in 2010, in Russia, from new handheld CB in the stores of radio communication user could see just Alan-42). At the same time, due to the nature of radio waves’ spread in the range of 27 MHz handheld CB radio stations, during the use in conditions of dense forests and rugged terrain, have tangible advantages over the widespread "license-free" radio stations of higher frequency ranges (LPD 433 MHz, PMR 446 MHz).
By using CB radio, you can contact the fire brigade, police, ambulance, emergency services through special dispatcher services, who will assist you by calling via telephone to the required service. For these purposes, is reserved channel 9C, where always are operating emergency services. But this is practiced just in few Russian cities.
Approximate range of radio communication between typical automobile/stationary and foreign handheld CB radio stations: between basic stations with the use of the reflection from the ionosphere - is almost unlimited, what it is easy to confirm (radio amateur can hear his echo signal that went around the earth), unfortunately, this kind of connection is unstable and depends on the state of the ionosphere. Usually it is able to connect with reporters at a distance no closer than 1500-2000 km.
• Between base stations - 30-80 km;
• between the base station and a car - 15-40 km;
• between the base station and portable - 10.3 km;
• between the automobiles - 5-15 km;
• between the automobile and a portable station - 7.2 km;
• between the portable station - 5.1 km.
In 1945, in the USA was held a Congress regarding civil radio communication, operated on 460 MHz–470 MHz UHF band. This communication was made to meet citizens’ needs in any personal problems, where it is impossible or difficult to use the telephone. Two years later was issued Document 6661, where were fixed the rules of the civil radio communication (CB-Radio) and distinguished two classes of licenses for transmitters - Class A (60 W) and Class B (5 watts). Public reaction to the introduction of classes of licenses and allocated frequency band was not always positive - expensive equipment, communications on VHF in urban conditions between movable objects is unreliable, etc.
Then all attention was paid to 11th-meter (27 MHz) section in the range of short waves, where has been already operated a variety of medical and industrial installations. Short waves can bend around obstacles up to several meters (for example, houses or small irregularities of the relief), they are relatively weakly damped in the forests. All experiments came from enthusiasts, and according to their results, for CB-Radio later was selected a range of 27 MHz.
In 1957 was accepted Document 11994, which introduced a class D of licenses. This class has still been using in the USA. First reaction of radio amateurs to the decision of the Federal radio communication service of the USA was negative due to the increased level of interference on the amateur range of 28 MHz. Simple equipment with broadband super regenerative receivers and unstable transmitters was used during those years.
But soon companies began to produce technically complex, but available equipment. 1959 was a year of key development of CB-Radio. 6000 users were registered, in 1961 - more than 200 000, in January 1977 already 500 000 users! At the moment in the USA and worldwide is registered a huge number of CB-clubs that unites people of interest, in most cases – it is holding of DX-ties and exchange of QSL-cards.
In the USSR the range of 27 MHz was allowed by the Decision of the State Commission of radio frequencies from 30 December 1988 (see "Radio" № 1 for 1991). However, initially CB-equipment in the USSR has a great number of severe limitations. Its power should not exceed 0.5 watts, channels in "zeros" for AM and for FM was allocated 10 special channels with a step ... 12.5 kHz (for example, radio station “Ural-Farmer” met these requirements). Apparently, this was done to make difficulties of "illegal" radio communications between USSR citizens and foreigners. Later equipment’s requirements have been relaxed and were close to the characteristics of real foreign CB-radio stations.
The main ones for CB in the world wide are channels, whose frequency start with 26965 kHz and reaching the grid, multiple of 10 kHz (26,975 kHz, 26,985 kHz, etc.). These channels has symbolic notation from 1th to 40th. Due to increasing number of users in some countries there was an auxiliary grid of frequencies and corresponding new channels. They also have a 10 kHz step, but shifted in frequency relative to the principal by 5 kHz. The first one got the number 51 (26960 kHz), the following - 52 (26970 kHz), and so on.
Later were introduced ranges that extend the number of channels to 200 and in some countries even up to 400. Some modern stations (with a view to shifted grid) support up to 800 channels. In Russia, for private radio communications were allocated channels, which in the world wide are considered to be as complementary, that is, with a shift of 5 kHz. But not all radio stations support extended range.
For the users’ convenience ranges were labeled with letters, the classic marking is, when the main range is denoted by the letter C. The most common is a description of the channel the following form: C9 FM or (C9E FM, C9R FM) - in it: the first letter ("C") denotes the range, etc. ("9") - the channel number for him - an optional designation ("C9R "), major (European) or minor (Russian) grid, and, in the end, - used modulation (" FM ").
Types of modulation
In the CBS are used three types of modulation: AM (amplitude modulation, amplitude modulation), FM (frequency modulation, Eng. FM, frequency modulation) and SSB (single sideband, single sideband modulation). Maximum transmission distance when using the AM and FM is practically identical. The majority of Russian users of CB use FM band, providing the highest quality sound (if the reporter signal is strong enough). Intelligibility on the limited range can be better while using AM, than using FM.
The usage of FM can suppress most types of interference that usually, as a rule, has amplitude character. AM is used (by tradition), long-distance drivers (the largest group of users of CB range, using the radio to AM). SSB is preferable from the view of achieving the maximum range (distance at comparable power output of the transmitter is much higher than AM and FM). The main obstacle of wide spreading of radio stations with SSB - the need for receiving a signal manually fine tune the frequency to achieve the best intelligibility and naturalness of correspondent‘s voice. Not all stations support SSB.
In each region, dispatching service (rescue service or similar according to functions) could be located on its frequency, but the most widely used channel is C9 FM (27065 kHz). Some radio stations even have the quick transition to that channel. Unfortunately, in recent years there is tendency to abandon from the maintenance of emergency communication channel at that range, and most of alert facilities, who had previously worked here - are closed [source is not pointed 224 days].
For the moment most resistant are services of metropolitan cities, namely, "Moscow Rescue Service” in Moscow (27,185 / 19C FM EUR) and “Neva” in St. Petersburg (27.635Mgts). Also known that some traffic police posts on the highway “Moscow - St. Petersburg” continues to observe on a 9 channel [source is not pointed 224 days], despite the fact that the information stands with the text "Rescue Service works in 9C FM» on the road, were changed to small plates about " emergency mobile number 112".
Beside of dispatching services, on CB exist so-called echo repeaters or "parrots". Echo Repeater – is stationary CB radio station, to which is connected repeater accessory and which repeats through the antenna of the repeater passed to her earlier, in the same channel, signal. Due to the large height of antenna’s installation, the repeater receives a signal, even from low-power portable or automobile radio stations in urban areas, and the repeater can be hearable in the same building conditions within a radius of tens of kilometers.
Echo Repeater allows mobile users to communicate, between them tens of miles. The advantage of the echo-repeater comparing with the base dispatcher station - that there is no need to hire permanent employees, who will always be on duty at the “base". Echo repeaters exist in many cities of the CIS countries; they are typically established by clubs of local motorists. For example, in Novosibirsk is the repeater "Hope" at a frequency of 27,635 MHz (channel 19D FM).
At the moment maximum output power of CB radios 10 watts is allowed in Russia, in addition to AM and FM also is allowed SSB. For the usage are also allowed the ranges C and D (26,965 ... 27,405 ... 27,415 kHz and 27,855 kHz). Channel 9 (27 065 kHz) is now formalized as a channel for emergency communications with police and emergency services. In the future, according to liberation of11th-meter range frequencies from official radio stations, users will be given other grids (26515 ... 26955 kHz, 26065 ... 26505 kHz).
Radio stations of this range are quite available for acquisition, but after the acquisition it must be registered. Free registration is made by territorial department at Federal Supervision Agency for Information Technologies and Mass Communication. However, often is required to receive call signal on a paid basis at the local Radio Frequency Center.
CB communication in Ukraine can be used almost freely, without permission. Reference to the decision of the NCRP 23.10.2008 № 1174 under these basic conditions (see Annex 6): - Operating range of frequencies 26960-27410 kHz. (40 channels of the grid C "fives") - Transmitter’s power less than 4 watts.