Research On QPSK Spread Spectrum Receiver And FPGA Realization

Spread spectrum communication has always been the frontier technology of the rapid development in the information age.With its many advantages in the field of communication,people have widely applied this technology from military-level applications to personal business expansion.Software defined radio technology is a way to realize the function of hardware platform by software programming.Upgrading software can solve the problem of hardware updating and make complex engineering easier.This paper systematically combines spread spectrum communication with software defined radio,realizes direct sequence spread spectrum communication system,and makes the design closer to science and technology life.In this paper,a spread spectrum communication system which can receive and transmit information is designed according to software defined radio technology.For the code synchronization module,it mainly includes the scheme design of code capture and code tracking,the simulation of MATLAB and the implementation of FPGA.At the same time,it proposes a serial capture method based on the traditional method and improved piecewise sum of squares.In addition,the information source is designed to group frames,the FIR filter is used for shaping filtering,the QPSK spread spectrum signal is modulated and demodulated,the FIR filter is used for matching filtering,the Gardner algorithm is used to complete bit synchronization and the final frame synchronization module.In this paper,the main modules are implemented on FPGA and simulated with ModelSim.The results of hardware debugging are verified with Chipscope online logic analyzer.