The Realization Of Four Level Signal Baseband Modulation And The Direct Mode Protocol On DMR

With the continuous development of private mobile communication system, the technology standard develops from analog to digital standard rapidly. Now, many kinds of private mobile communication technology standard exist. Because DMR(Mobile Radio Digital) standard technology is simpler, lower cost, higher frequency spectrum utilization, etc., manufacturers are particularly concerned about this standard.This paper studies the realization of DMR protocol and the four level baseband modulation mainly. Firstly, the DMR protocol, the four level baseband modulation, call response protocol and transmission signaling coding technology are introduced. Secondly, it gives the four level baseband modulation technology which includes integer interpolation technique and the baseband pulse shaping filter technology and makes a simulation on baseband pulse shaping filter. The DSP realization of the four level baseband modulation and its performance are presented, consequently design scheme of shaping filter is confirmed. In addition, it designs modulation model program based on OMAP-L138 chip and tests baseband simplex experiment of transmitter. Finally, this paper analyzes call response protocol and designs transmission signaling whose code/decode procedure is explained. Super frame transmission program including signaling code/decode, the state transition of DSP and ARM in the calling process and the DSP program of call response protocol are designed. After that, this paper makes an experiment on super frame transmission and call response and the result of the test is realized.