Research And Base-band Design Of Code-hopping Spread Spectrum System

As a new kind of spread spectrum communication mechanism, code-hopping direct sequence spread spectrum (CH-DSSS) communication has been used to enhance the concealment of communication and the performance of anti-interception. Combining parts of the advantages of DSSS and FH, CH-DSSS communication is an extension of conventional DSSS system on the basis of principles of frequency hopping (FH) communication, and has become a new means of anti-interference in military communications.Recently,with the rapid development of microelectronics and EDA, programmable logic devices represented by CPLD and FPGA have been widely used in digital signal processing. In this thesis, A code-hopping spread spectrum communication baseband system based on the FPGA hardware platform is realized, which involving the principles of spread spectrum communication and FPGA,as well as VHDL and the Quartus II development platform.The aim of the system is to achieve a code-hopping spread spectrum communication baseband system with high integration, strong flexibility and great data processing capability.Firstly, the research status and principles of the CH-DSSS communication are introduced, the mathematical and physical model, signal character, performances of anti-jamming and anti-reconnaissance of CH-DSSS are also analyzed. Secondly, according to the theoretical analysis, the structure of all digital code-hopping spread spectrum baseband system is proposed,including the generation of the code-hopping sequence and the code-hopping pattern, the implement of code-hopping synthesis technology as well as the information code input and spectrum spread. Finally, the design of the baseband spread spectrum signal and the synchronized acquisition circuit is completed with each unit of the system simulated with Quartus II.