Design And Implementation Of A Module And Demodulation Module For Wireless Communication Between Vehicle And Ground Of High Speed Maglev Train

As a non-traditional rail transport,high-speed maglev train has been included in the construction of national high-speed transportation system.And in the 13^th Five-Year Plan,600Km/h high-speed maglev transportation project was launched.When the maglev train runs at such a high speed,its operation state is mainly managed by the ground control center.Because there is no mechanical contact during operation,the ground control center communicates with the train by wireless mode.But the control information in the form of digital baseband signal is not suitable for wireless communication.Therefore,it is necessary to convert digital baseband signal into signal form suitable for wireless communication through modulation and demodulation,so as to complete the information exchange between ground control center and train.Modulation module,as the intermediate frequency part of wireless communication system,usually has low working frequency and needs up-conversion circuit.Up-conversion circuit not only increases the complexity of the system,but also introduces additional noise.Demodulation module as the inverse process of modulation module also faces the same problem.With the development of direct frequency conversion technology,the working frequency of modem module becomes higher,the hardware structure is simplified,and the design of modem module faces new challenges and development.In this thesis,a modulation and demodulation module for high-speed maglev train with 38GHz millimeter wave vehicle-ground wireless communication system is designed and implemented.The main research contents are as follows:1.Design and implementation of modulation module.In this thesis,the structure of direct frequency converter transmitter is adopted.Combining the advantages of digital circuit and analog circuit,a modulation module with high IF output frequency,adjustable numerical control and simple hardware structure is designed and implemented.2.Design and implementation of demodulation module.In this thesis,the structure of direct frequency conversion receiver and incoherent demodulation are used to analyze the multi-channel demodulation module,and the single-channel demodulation module is designed and implemented.3.Experimental test.The closed-loop test of the modem module is carried out,and a simple BER test module based on the development platform of FPGA is designed to test the modem module.In addition,the modem module is used as the transmitter and receiver of wireless communication for wireless communication test.