| Trunking Communication System is one of the most rapidly growing special mobile communication systems. It belongs to a group mobile dispatching system for special mobile communication purpose. During the development of mobile communication technology, trunking system is transferring from analog to digital system. DMR is the latest digital mobile communication system which the ETSI is developing. As the new communication system, DMR is engaging more and more concentrations from communication organizations and device providers. First this paper introduces some key technologies of physical layer in DMR system,including 4FSK modulation/ demodulation,synchronization,code/decode,burst format,channel timing,etc. This paper focuses on the theory of 4FSK. After the algorithm verification and simulation based on MATLAB,the 4FSK modulation and demodulation are realized in DSP on a kind of DMR baseband printed circuit board. In addition,the paper discusses the establishment of 2-slot TDMA structure,slot synchronization,real-time data exchange between DSP and MCU/AMBE-2000. Finally, simplex and duplex baseband speech communication are carried out as well as simplex radio communication , and the performance measurement of the whole transmission system is presented . |
PDF Full Text Request