What is CB communication
With the development of transportation and communication, some countries have launched a two-way radio communication service for citizens in order to open the common property-radio waves to ordinary citizens. This kind of personal communication in the citizen band is called CB (CiTIzenBand). CB is mostly used for automotive communication , Can provide road conditions, driving directions, to strengthen the relationship between cars when driving, increase driving safety. This is a two-way radio communication service that can be set up without qualification restrictions. According to the country's situation, each country allocates an appropriate frequency for citizen communication. Now take Japan as an example: since June 1961, the country has adopted eight channels in the 26MHz and 27MHz bands as dedicated channels for citizen communications, and at the same time stipulated that the antenna output power should be below 0.5W. Computer and submit an application to the relevant management department to obtain a CB radio station license for radio communications.
Because the civilian radio station in the civilian frequency band is easy to use and can be used by anyone, it is very popular. As of December 1982, there were 260,000 radio stations in civilian bands approved throughout the country. Since the radio station in the civilian frequency band only allocates 8 channel frequencies, it is easy to cause mixed station interference in the city, which is not very practical. Therefore, some users of radio stations have privately modified their transmitters to increase the transmission power or illegally use channels that have not been approved, which has interfered with radio, television and other wireless communications, causing social problems.
In addition to taking tough measures to ban illegal radio stations, the government approved the establishment of a personal (Personal) radio station in December 1982, as a new personal communication method to solve the problems of civilian radio stations in the civilian frequency band in the past.
In lieu of the personal radio station used for civilian radio stations in the past, as long as you purchase a radio transmitter with the technical certification of the Radio Equipment Appraisal Committee of the consortium, anyone can conduct radio calls without being qualified and can also be used as a car radio station.
This personal radio station uses a frequency of 900MHz in the UHF band, the antenna output power is 1-5W, and its talking range: 4-5km in urban areas, 8-10km in suburbs, there are 80 channels, and the radio transmitter can automatically Exploring the idle channels, which can reduce interference from radio stations in the civilian band. The personal radio station can automatically transmit the call signal. Therefore, the radio management department is easy to find illegal radio stations.
When the personal radio station obtains the license, the relevant authority must record the license number on the ROM (only memory) disk, otherwise the radio transmitter cannot be used. This kind of disk helps to identify the transmitter, and the transmitter can also automatically send out its own call signal, so the radio management department can prevent the illegal use of radio.
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