Development Of A Transpoder Telemetry Data Transceiver System Based On PXI Express Platform

Modern missiles,rockets,planes and other aircrafts are constituted by many subsystems,and the wireless telemetry data transmission between the aircraft and the ground station is guaranteed by transponder,which is treated as an important part of the aircraft.Therefore,it is very essential to test the telemetry data transceiving function of transponder before the launch of aircraft.However,every transponder has different communication protocols,and the amount and rate of data transmitted between transponder and ground station are also increasing.As a consequence,higher and higher requirements are put forward for the function and real-time performance of the transponder test system.Due to the poor flexibility and versatility,traditional test instruments and equipments have been unable to meet the comprehensive coverage test of all types of transponders.To sum up,a modular radio frequency hardware platform based on PXIe is used to build a transponder telemetry data transceiver system with good flexibility,versatility and high integration in this project,completing the construction of a communication link with a certain type of transponder,laying the foundation for comprehensive testing.According to the transponder telemetry data transmitting and receiving function and protocol requirements,this paper presents the overall scheme of telemetry data tranceiver system based on PXIe bus.The generation of telemetry data is accomplished by using vector signal generator and FPGA coprocessor,the real-time demodulation of telemetry data is accomplished by using vector signal analyzer,and LabVIEW is used as the software development platform of the system.In the signal transmitting end,the direct digital frequency synthesis technology is used to complete the signal generation in the FPGA,and the vector signal generator is used to realize the signal transmission.In the signal receiving end,this project study the principle and implementation method of polyphase digital down-conversion,completing the design of two key modules,parallel numerical control oscillator and polyphase decimation filter.Moreover,the design and simulation of polyphase digital down-conversion module is accomplished by this paper based on Vivado.In addition to digital down conversion,this paper also research symbol synchronization technology based on Gardner timing error detection at the receiving end,and propose a real-time demodulation method of 2FSK signal based on envelope detection and Gardner symbol synchronization technology,realizing the demodulation of telemetry data in FPGA.Finally,this paper uses Barker code peak detection to complete the frame synchronization of received data and display the results in the host computer.In addition to this,this paper also completes the design of the instruments' control program,realizing the function of the received signal's waveform and spectrum displaying,and the function of real-time data storage.Finally,the signal processing functions of the system's transmitter and receiver are verified through the actual communication with the transponder,and the actual test of the system is completed.The test results show that the system can reliably and effectively complete the task of sending and receiving telemetry data.