The Design Of Receiver Front-end Splitter In Trunk Communication

Trunk Communication is a kind of wireless dispatching system, which can share resources, signal channels and services. Trunk communication is mainly used in various fields of control and dispatching, such as, public security, transporter, factory and mining corporation, etc, as well as Point to Multipoint group call module. The system is mainly combined of terminal equipment, base-station and central control station.350MHz frequency band is exclusive usage for the command and dispatching of police affair private network. As the important unit of Trunk communication base-station receiver front-end, the splitter has the feature that can filter the out-band spectrum, keep better front-end noisy, as well as have the function of signal amplification, channel power distribution, which is the key point of Trunk system Packet Dispatching function.Due to the large cover area and difference with the dense deployment of cellular mobile telecommunication network Base Station (BS), Trunked Base Station (TBS) always has high transmission power, then it will easily cause the adjacent channel interference. Therefore, branching unit is requested to have strong restrain ability on transmission frequency signal. The traditional branching unit, usually uses comb linear body structure as pre-selector filter, and uses high quality factor of body structure to get smaller insertion loss and higher out of band rejection. By doing that, although we can get better noise characteristic and restrain ability on transmission frequency, meanwhile there are also other problems, such as large volume, heavy weight, relatively higher price, etc. As the continuous development of Trunked Technique and improvement of networking mode, the overall request for front receiver device, also has continuous improvement, which means not only fits availability, but also meets economical efficiency. The main improvement direction is miniaturization and low cost.The system combination and work principle of the Splitter is presented in this paper. Based on the system analysis, the whole machine criterion is divided into each system component criterion. Then the principle, design method and design outline are mainly proposed. According to adopting reasonable technique style and optimization design, at last, the Trunk splitter with high performance and low cost, will be worked out.