The Research Of Four Level Signal Baseband Demodulation Technology And Implementation Of DMR Terminal

With the rapid development of digital communication technology, the digital special wireless communication system has been the trend of The Times. In this process, International organizations put forward multiple digital radio protocol standards?Whereas DMR(Digital Mobile Radio) hold an advantage in the digital interphone market,it is put forward by the European Telecommunications Standards Institute(ETSI) as the latest global open special digital wireless communication system standard.This paper mainly studies DMR baseband demodulation technology and implementation in DSP.The article first introduces the development and prospects of special digital wireless communication system.Then presents parts of DMR protocol about baseband transmission and modern digital synchronization technology,gives the synchronization performance indicators,and illustrates the synchronization algorithm adopted by this paper.Secondly, put forward the DMR transceiver baseband demodulation module implementation scheme, then the whole demodulation process is simulated in Matlab, as the same time,the suitable for DMR frame synchronization and bit synchronization algorithm is direct realized in dsp. then introduces the hardware platform and software platform based on L138,on the basis of this platform, the voice processing program,the simplex demodulation module program, duplex transmission profram are developped.Finally, introduces a series of experiments of the DMR transceiver development process, the experimental results show that: the baseband transmission error performance is good, the voice transmission voice is clear.verify the validity of the transmission scheme.