FPGA Implementation Of Wireless Data Transmission System Based On DQPSK

DQPSK modulation and demodulation technology has excellent anti-noise performance and high spectrum utilization,and it overcomes the shortcomings of phase ambiguity.Therefore,it has a wide range of applications in high-speed satellite communication and high-complexity cluster communication.Based on the requirements of a digital transmission simulator project,a wireless data transmission system based on DQPSK and DSSS-DQPSK is designed and implemented on the FPGA hardware platform.The research content has important theoretical and practical value.Firstly,it designs and implements the FPGA system,which is based on DQPSK mode,and then it analyzes some core modules such as modulation and demodulation,differential codes,shaping filtering,frequency offset estimation,carrier synchronization and bit synchronization.After that,it shows the RTL diagram and some core codes of these modues.In order to verify the feasibility and effectiveness of the system,it finishs the VIVADO simulation and gives relative results.Secondly,it designs and implements the DSSS-DQPSK system based on FPGA.Then it analyzes The PN code generation,multi-rate transmission,pseudo-code capture and pseudo-code tracking module in detail.The RTL diagram and core codes of these core module are given.After that,the feasibility and effectiveness of the system is verified by VIVADO simulation results.In addition,in the pseudo-code tracking module,the improved pseudo-code tracking loop structure is proposed and implemented for the difficulty of debugging of the original classic early-morning gate pseudo-code tracking loop scheme,and its reliability and effectiveness is verified by VIVADO simulation results.Finally,an adaptive threshold voltage scheme is proposed and implemented in order to solve the problem of the difficulty in pseudo-code capture caused by fixed threshold under different channel conditions.Finally,in order to facilitate the setting of the working mode,data collection and calculation drawing of the wireless data transmission system,it designs a host computer by serial port communication,which is based on Java language.The host computer has the advantages of simple and convenient operation,at the same time,people can easily understand the results of the system from it.In addition,it conducts on-site functional testing and various indicators testing of the wireless data transmission system to verify the effectiveness,stability and reliability of the whole system functions.