Research And Implementation Of Physical Layer For Police Digital Trunking Terminal

PDT(Police Digital Trunking)system uses domestic encryption algorithms,owns independent intellectual property rights.It has the characteristics of interconnection,wide coverage and low cost.It is a command and dispatch system,which is a smooth transition from domestic police analog trunking system to digital trunking system.The police digital trunking terminal is one of the necessary equipments for the police digital trunking system.The physical layer of the police digital trunking terminal implements modulation,demodulation,synchronization and channel codec functions.The key technologies of the physical layer directly affect the performances of the terminal.Therefore,the research and implementation of the physical layer for the terminal is of great significance.Based on the review of the research status of physical layer for digital trunking terminals at home and abroad,the physical layer of the police digital trunking terminal is studied and implemented.The main works of this thesis are listed as follows:1.The architecture of police digital trunking terminal protocol stack and physical layer protocol are analyzed.The structure of the physical layer for the terminal is proposed.The functional modules of the physical layer for the terminal are divided.The compositions and basic functions of the hardware platform for the A6 terminal are analyzed.2.A functional architecture of the physical layer for the police digital trunking terminal is proposed.The interface of the physical layer for the terminal is defined.The buffer of the physical layer for the terminal is designed.According to the principles of modulation and demodulation,synchronization and channel codec,the modulation and demodulation module,synchronization module and channel codec module are designed.The Matlab simulation software is used to verify the key technologies of the physical layer for the police digital trunking terminal.3.A software architecture of the physical layer for the police digital trunking terminal based on A6 platform is proposed.In the Cygwin development environment and A6 terminal hardware platform,the modulation and demodulation module,synchronization module and channel codec module of the physical layer for the police digital trunking terminal are developed by using C language and SMC state machine.The modulation and demodulation,synchronization and channel codec functions of the physical layer for the police digital trunking terminal are realized in TMO mode.RMO mode and DMO mode.4.The functions of each module and the performances of the physical layer were tested by using Cool Watcher and 3920 integrated tester.The test results demonstrate that the modulation and demodulation,synchronization and channel codec modules realize the functions of the physical layer for the police digital trunking terminal,and the performances of the physical layer meet the performance requirements of the physical layer for the police digital trunking terminal.