UHF CB and its frequency band deployment

　　HF CB is a category licensed citizen band radio service in the UHF 477 MHz frequency band authorized by the governments of Australia, New Zealand, Vanuatu, and Malaysia. UHF CB provides 77 channels, of which 32 channels (16 outputs, 16 inputs) are allocated to relay stations. It is conceptually similar to the Universal Mobile Radio Service in the United States.

　　Equipment and License

　　The user device design is similar to commercial land mobile two-way radios, but the maximum legal output power is 5 watts. External antennas are allowed, with commercially manufactured antennas having a gain of up to 12 dB. Allow the use of handheld transceivers (handheld walkie talkies) with a transmission power of 500 mW to 5 W (fully legal power), which are relatively inexpensive compared to full-size transceivers. The operation of this frequency band is limited to F3E and G3E modes (FM or PM for analog voice calls), except for channels 22 and 23, which are only data modes.

　　Class license refers to users not needing to apply for a license or pay a license fee; However, they must comply with the regulations of the category license.

　　Repeater

　　Repeaters extend their transmission range by using antennas located at high altitudes (usually mountaintops, high-rise buildings, or radio towers) to receive and automatically rebroadcast transmissions. Sometimes, a transmission range of over 100 kilometers (60 miles) can be achieved through the use of repeaters. The repeater is located on channels 1-8 and 41-48, and the duplex button should be pressed to access the repeater.

　　Typical fixed wireless access

　　1. User Unit: Receive wireless signals from base stations, demodulate and decode them to restore analog audio signals, and send them to user terminals (such as telephones, fax machines, data modems, etc.). It is a wireless transceiver carried by users or fixed in a certain location, divided into fixed, mobile, and portable types, providing users with standard interfaces for terminals such as telephones, fax machines, data modems, etc., and can also be integrated with terminals. It is connected to the base station through a wireless interface and transparently transmits the services and functions that the switch can provide to end users. It can be divided into single user units and multi-user units.

　　2. Base station: A base station is a wireless transceiver device controlled by a controller that serves a small community and provides a wireless channel with user units through a wireless interface; A wireless base station is usually a multi-channel wireless transceiver located in a central position, with a transmission range called a "cell" (omnidirectional antenna) or a "sector" (directional antenna), and a coverage range ranging from several hundred meters to tens of kilometers.

　　3. Base station controller: also known as central office or wireless port controller, its function is to provide interfaces with base stations, networks, and operation and maintenance centers, provide wireless channel control and base station monitoring functions, and complete the transfer with switches. It determines the circuit allocation for each user and monitors the performance of the system. The transmission network between the base station and the controller can be selected based on factors such as user distribution, geographical environment, and loop reliability to form star shaped, tree shaped, or ring shaped transmission networks, using twisted pair cables, fiber optics, or digital microwave transmission systems.

　　4. Network Management Center: Manage the entire fixed wireless access system. Its functions include configuration management, fault management, performance management, security management, and billing management.

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