The Cni Radio Frequency Integrated Avionics System Technology Research

The integration of electronic system has been the most popular research in theavionics system. Communications, Navigation and Identification(CNI)system palys avital role in avionics system, and the integrated CNI system has important significanceon the development of the entire avionics system integration. To implement theintegration, the concept of ‘Software Radio’ was proposed and to solve the technicalmatters, a standard, modular and open hardware platform was constructed and then itcan use the software to implement all kinds of functions. In the process ofimplementation, RF integration is the major problem which is also the main researchobject in this paper. For the system architecture and key technologies in the integrationof the CNI subsystem, the exploratory research in this paper mainly include thefollowing aspects:1. For the JTIDS, IFF and satellite navigation signals which are in the L-band inCNI system, a method of RF direct bandpass sampling that based on SDR architectureis proposed with referencing the development of high-speed data acquisition technologyand then the feasibility is verified with using the modular instruments based on PXItechnology to build the test system.2. To implement the receive of wideband signal with mixture of strong and weak,a multiple frequencies wideband power equalization is designed for the CNI system tosole the key problem in wideband automatic gain controller(AGC). In this design, theconditional design method has been abandoned and we start with the concept of powerequalizer and also according to the using of the characteristics of electrical tunable filterand the amplitude-frequency characteristics of notch filter, we finally implement theequalization control between the multiple signals.3. For the digital part in the digital AGC system, we implement the DDC with themethod of harmonic subsampling, avoiding the cost of multipliers in the process ofmixing. And also we implement the decimation and filtering with the high-efficientpolyphase structure and distributed arithmetic, effectively reducing the usage ofresources in FPGA. Then we implement the detection with the high-efficient CIC filter and do the optimization and improvement. For the control of front-end, the controlalgorithm is specially designed using the LUT. This design can effectively reduce theresponse time in the AGC loop, and finally we implement this design in the FPGAhardware.4. According to testing the modules in the integrated system, we verify thefeasibility of the program, which prove that it can be realized in the practicalengineering.