Development Of 2FSK Signal Realtime Modulation And Demodulation System Based On PXI Platform

As the digitization of various types of aircraft continues to increase,the amount of data that needs to be transferred between aircraft and the ground station will continue to increase,and the transmission speed will continue to increase.As a result,the performance and speed requirements for the data processing of aircraft transponders will continue to increase.Therefore,advanced transponder testing is required and the ability of the test system also puts forward higher requirements.Facing modern transponders with complex structure,the traditional test system communication link can hardly meet the real-time requirements,and cannot completely simulate the working process of the transponde r in the aircraft flight process.The transponder cannot be fully tested.Therefore,there is an urgent need for the test system to be able to send uplink control commands in real time,receive the downlink data of the transponder in real time,and establish a real-time high-speed data transmission communication link with the transponder.This project uses a modular radio frequency hardware platform to develop a real-time transceiver system based on the PXI platform,and completes the 2FSK signal modulation and demodulation,which lays the foundation for the subsequent development of universal automatic test systems for multiple types of transponders.In this thesis,with considering the system hardware requirements and software requirements,the system hardware solution based on PXI platform and the software solution based on Lab VIEW virtual instrument are proposed.The system development is mainly divided into two parts: transmit ting link design and receiving link design.This thesis first studies 2FSK modulation method based on peer-to-peer technology between different PXI devices,and the system generates the 2FSK signal through PXIe-5673 E vector signal generator and PXIe-7976 R FPGA coprocessor.Then,this paper researches the real-time processing of 2FSK signal of receiving link,demodulation and synchronization methods,and the system developed on-board FPGA in the Intermediate Frequency Digitizer PXIe-5624 R completes down-conversion signal receiving function based on the PXIe-5668 R vector signal analyzer.Finally,the project designs a host computer application program to achieve the above-mentioned modular instrument control and digital signal processing functions in FPGA.The front panel of the Lab VIEW program has a good human-computer interaction interface,which can display the status of each component of the system.It is convenient for observation,analysis and storage of real-time data signals,completing system development,BER testing and other functions.At the end of this thesis,functional verification is performed on the system transmitting link and receiving link,and the BER test is completed.The results show that the system meets the requirements and can complete the real-time modulation and demodulation of 2FSK signals.