Design And Implementation Of Police Digital Trunking Communication System

Seen From the development of digital communication system, the digital cluster communication industry is in the initial stage of development. The most direct problem is that the cost of cluster system and terminal equipment is relatively high, maintenance, upgrade and expansion. In order to break through the monopoly of foreign technology, reduce the cost of terminal equipment, and better protect information security, research and design the professional cluster communication system with Chinese characteristics, has far-reaching significance to the development of our country’s cluster communication.First, this paper from two aspects of technology and economy, the police trunking system were feasibility study, the user number of research and communication, in order to meet the needs of users, the police digital trunking standard channel using interval 12.5KHz. Each of the frequency division for two slot, the frequency utilization rate than MPT1327 analog cluster can improve the 4 times, pure code rate should be lower than the 16kb/S, codec delay should be controlled within 10 milliseconds.Secondly, this paper analyzes the requirements of the call control module, voice processing module, routing and forwarding module, link detection and control module, channel resource management module, resource management module six functional module design and detailed design, determine the specific function of the system.Next, based on the collected on the basis of traditional standards of digital trunking system, the thesis introduces PDT(Police Digital Trunking System) digital trunking communication system using the standard protocol. Compared to PDT and traditional trunking communication system, the police digital trunking communication with spectrum utilization rate is high, the signal fading ability, good secrecy, high stability. The paper analyzes and studies the heartbeat detection algorithm and the flow control algorithm and the call establishment priority algorithm.Finally, this paper uses the method of white box and black box method to test the main functional modules of the system, the test results basically reached the protocol requirements of PDT system. Response time needs to be further improved.The system has been applied to the cluster communication manufacturer in China. The standard of international standards of mature technology for reference and innovation design integrate professional communication experience, reduces the cost of equipment, and solves the foreign technology blockade, Promote the development of digital communication in China.