Design Of Direct Sequence Spread Spectrum Communication System Based On ZYNQ

With the advancement of science and the development of society,people's demand for high-speed video image data transmission services continues to grow.At the same time,more attentions have been focused on the security and reliability of communications.Spread-spectrum communication systems have the advantages of high confidentiality and robust anti-interference capacities.Among them,direct-sequence spread-spectrum communication system has become a research hotspot because of its simple structure and easy implementation.In this technology,the design of the transceiver is the one of the key parts of it.Different from the traditional methods of using FPGA to implement direct sequence spread spectrum transceiver,the thesis uses Xilinx's ZYNQ chip to design the communication system.The direct sequence spread spectrum modulation and despread demodulation are performed on the FPGA of ZYNQ chip.The ARM core and the upper computer exchange data through the UDP protocol.The design of the communication system mainly includes the upper computer programming design,the ZYNQ interface programming design,the baseband programming design,and the RF front-end.The design of the direct sequence spread spectrum communication system based on ZYNQ in the thesis mainly completed the following works:Firstly,completed the design of the upper computer programming with JAVA language:programming design in the transmitting mode and the receiving mode.In the transmitting mode,the software selects the pictures or documents in the computer,then packages them into data packets.In the last,it will send them to the ARM core of the ZYNQ chip.In the receiving mode,our design reassembles the data packets sent by the ZYNQ chip into pictures or documents,and stores them on the computer's data storages.Secondly,completed the design of the interface programming of ZYNQ.The ZYNQ interface programming includes an ARM program and an IP core for serial-to-parallel conversion of data between the ARM core and the FPGA core.Through the IP core designed by myself,data can be transmitted between the ARM core and FPGA core of ZYNQ through Xilinx officialBRAM.Thirdly,completed the design of the baseband programming and the RF front-end: the baseband programming is mainly used to complete the spread spectrum modulation of the original data,despreading and demodulation of the baseband signal.In addition,through the design of the radio frequency front end,not only can achieve the conversion between radio frequency signals and baseband signals,but also can achieve cyclic utilization of the device to save resources.Lastly,tested the communication system: after designed on VIVADO,the ZYNQ programming is downloaded into the board for testing.The system test is divided into sending test part and the receiving test part.In short,it includes the test on the host computer,the test of the baseband programming and the test of the RF front-end.After finishing all the tests above,the system is ready to work.In summary,the thesis uses ZYNQ to design a direct sequence spread-spectrum communication system.After completing the design of upper computer software,ZYNQ interface programming,baseband programming,and the RF front-end,the system was tested thoroughly.The experiment results showed that our system can work correctly.The direct sequence spread-spectrum communication system designed in this thesis can reduce radio frequency components and save resources.Our design of the communication system could be a good reference for future research on similar projects.