Research On Modulation Technology For Digital Multimode Radio In Aeronautical Communications

With the rapid development of China's civil aviation industry,the problem of low localization ratio of civil aviation communication equipment is becoming increasingly serious.The high purchase cost of imported equipment and the hidden danger of security without independent intellectual property rights have seriously affected the healthy development of China's civil aviation industry.In recent years,with the vigorous support of national policies,domestic civil aviation communication equipment manufacturers have gradually improved especially domestic ground-to-air communication equipment,whether in function or reliability,has been greatly improved.However,domestic civil equipment is difficult to compare with imported equipment in terms of function and technology,and most of them are still at the level of analog equipment.In addition,most of the domestic civil equipment has the defects of single modulation function and difficult function improvement,which can't meet the needs of the new generation of civil aviation ground-to-air communications.In this paper,a design scheme of digital multimode modulation unit based on DSP and DDS is proposed to solve the problems in modulation function of the above-mentioned domestic ground-to-air communication equipment,which is intended to realize a new generation of civil applications.The multimode modulation function of ground to air communication equipment.Through the theoretical study and simulation of the required modulation mode,this paper discusses the four main modulation modes and their difficulties.In practical engineering,the multi-mode modulation scheme is realized,and the feasibility of the scheme is verified according to the actual results of the equipment.The main contents of this paper can be summarized as follows:1.According to the business requirement of the new generation ground-to-air communication of civil aviation,the function requirement of civil aviation to ground-to-air communication equipment is determined,that is,one equipment is needed to be compatible with four modulation modes at the same time.Through the theoretical research and software simulation of the four modulation modes,a scheme for realizing multi-mode modulation equipment by switching modulation mode through software is determined.2.Hardware work: According to the selected scheme for device selection,to achieve voice processing,single-chip processing,digital modulation,PLL,mixing and VGA,power conversion circuit schematic design,and PCB plotted;3.Software work: ARM,DSP,DDS,ADC,DAC,VGA and other chip driver and application programming,mainly including a variety of communication associations.Discussion,peripheral configuration,and software programming implementation of the most important digital modulation function;4.Debugging and testing work: The welding,software and hardware debugging,function testing and index testing of PCB are completed.The test results show that the proposed scheme can meet the engineering design requirements.