Introduction to Amateur Radio Communication
1. 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.
Second, the difference between CB and amateur radio
In foreign countries, the radio stations used by individuals are divided into two categories: citizens' personal radio stations and amateur radio stations. The use of amateur radio stations requires the qualification of radio professionals, while the use of civilian radio stations, as long as the radio transmitters that have passed the inspection have been purchased, anyone can obtain a license.
The personal radio is a personal communication system that emerged in the 1980s and is also the second CB (civil band) radio. It differs greatly from the original CB in frequency, output power, and antenna.
Personal radio is different from the amateur radio station introduced earlier. Taking Japan as an example, the differences are summarized as follows:
1. Radio license amateur users must pass the national examination to obtain the qualification of amateur radio check-in, or study at the training seminar organized by JARL. After passing the examination, the station must have a radio license. Regardless of the qualification of the personal radio, if you purchase the specified transceiver when you set up the station, you only need to apply to the relevant management department to obtain a readable memory cartridge.
2. The working frequency amateur radio can be used in 3.5, 7, 21, 28, 60, 144, 430MHz and other frequency bands even if it is the fourth-level check-in qualification, and it can freely QSY (replace frequency) in each frequency band.
The personal radio has 80 channels in the 900MHz frequency band, and only one channel is its calling channel. It can perform QSO with the remaining channels, and it is easy to operate. It does not need a knob to select the channel. It is automatically borrowed by the CPU (central processing unit) in the transceiver Channel selection is very convenient.
3. Amateurs who are qualified for amateur radio check-in can use AM, SSB, FM, RTTY, SSTV fax and other equipment.
Personal radios are only allowed to use FM (frequency modulation) phones.
4. The fourth-level amateur radio check-in qualification for transmission power is 10W at most, and it can be used for overseas communication in high frequency bands.
The personal radio is limited to 5W. Although a 50W linear amplifier is commercially available, it is not allowed to be used, otherwise it is illegal.
5. Antenna amateur radio can use any style, any highly augmented antenna, and can be self-made.
Personal radio stations must use antennas that comply with the regulations and must not make their own. The height is not limited, but in the 900MHz UHF band, if the erection is too high, the coaxial cable used as the feeder is too long, but it will cause problems of attenuation and too much loss.
6. The other party's amateur radio can communicate with amateur QSOs all over the world.
Personal radios can only communicate with counterparts in their home country.
7. Communication content Amateur radios cannot be used for profit-making or for third-party communication, and passwords are not allowed in communication.
Personal radio stations can make commercial communications for profit, but password communication is not allowed.
8. Equipment Manufacturing Amateur Radio can assemble the equipment by itself. In order to discuss technical issues, the equipment can be modified.
Personal radios are not allowed to be self-made, they must use the specified type and qualified finished telephones, so they cannot be disassembled at will to expand their communication distance.
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