Research And Realization Of DMR Terminal Baseband Transmission Technology

Trunked Radio System is growing rapidly today, due to its unique scheduling and group calling function, and characteristic of quick call, it has played a tremendous role in special communication field. During the development of mobile communication technology, trunking system is transferring from analog to digital system. DMR (Digital Mobile Radio) is the latest Digital Trunking Communication System standard proposed by the international organization ETSI, the modulation method of which is 4FSK.The paper mainly studies DSP algorithm implementation of DMR baseband transmission technology. The paper outlines the physical and the data link layer protocol, interpolation and extraction, digital filtering technology, frequency demodulation technology, which are related to DMR baseband transmission.It gives the DSP algorithm implementation, mainly including pulse shaping filter design, the origination of 4FSK baseband four level modulated signal in transmitter, sampling and judgment of 4FSK baseband demodulated signal in receiver. For judgment, the paper proposes an algorithm for adaptive threshold. In addition, the paper gives simplex and duplex real-time DSP program on TMS320VC5510. Finally, on the hardware platform of baseband circuit board and baseband plus rf circuit board, respectively achieved baseband transmission and wireless transmission of simplex and duplex voice transmission and error performance testing.