The Research Of IF Digital Receiver Technology Based On DPMR Protocol

According to the letter not letter [2002]127,[2002]10and［2009］666which is issued by Radio Administration of the Ministry of InformationIndustry and the dPMR protocol which is launched by the EuropeanTelecommunications Standards Alliance (ETSI) for civilian digital radio,this paper designed the IF digital receiver of900M system based ondPMR protocol. The dPMR protocol is on the infancy stage in China,therefore, researching the system has its practical significance. The IFdigital receiver module of the system has researched under the noise andthe Doppler effect. Major research works are as follows:Firstly, with the development of wireless communications anddigital signal processing techniques, the IF digital receiver module basedon software radio technology is applied to the system. Digitaldown-conversion technology is an important part of the IF digital receivertechnology, the paper has researched the digital down-conversion modelof the traditional Software Radio. An improved digital down-conversionmodel is used for solving the problem which is that the half-band filtercould not extract2Mtimes in the traditional digital down-conversiontechnology. Then, the research of traditional analog phase-locked loop theory isto deduce the structure of the digital phase-locked loop. This paperstudies several PLL algorithms, compares the PLL algorithm based on thecostas loop, and the designs digital PLL loop filter. NCO is achieved bythe look-up table algorithm. And then this paper studies the basic functionof FLL, and designs the loop filter for FLL. Comparing several automaticfrequency tracking algorithms is to identify the optimal algorithm of FLL.The noise immunity and the anti-Doppler effect performance of PLL andFLL is analyzed and compared, and the paper has designed an improvedsecond-order FLL secondary second-order PLL carrier synchronizationmodel, and given results of simulations.Finally, according to dPMR protocol, four kinds of complex ad hocnetwork call model with call management approach are researched fordifferent occasions. Under the premise of Specific signal indicators andthe coexistence of noise and the Doppler effect, two improved IF digitalreceiver model is simulated by matlab, and realized by C languageprogram, and adopted on base station functional prototype.