Design And Implementation Of A Missile-borne Spread Spectrum Communication System Based On AD9361

Spread spectrum technology has been widely used due to its excellent confidentiality and anti-interference.However,a high dynamic change of Doppler frequency will be caused by the rapid change of speed and motion trajectory.In the case of high dynamic conditions,the spread spectrum signal is difficult to be captured quickly.Therefore,it has high value to study the acquisition of spread spectrum signal with high-dynamic features.Based on a projectile firing correct system,a set of spread spectrum communication system which can be loaded in artillery shell has designed in this paper.The main work includes the following:(1)Research and improvement of high dynamic capture tracking algorithm:This paper studies the fast acquisition and tracking algorithm for high-dynamic Doppler frequency offset.Three acquisition algorithms are studied,and the improved FFT frequency offset estimation algorithm which has better anti-interference performance has deeply analyzed.Then the high dynamic tracking algorithm for high dynamic conditions has studied,and the analysis of the tracking loop has completed.(2)Hardware design and implementation of missile-borne digital transmission ratio:In order to work in the specific environment,the hardware design and implementation of the missile-borne digital transmission ratio has completed.It has the characteristics of miniaturization and low power consumption.Also,this set has the advantages to bear high overload,and it can also work in the environment with high or low temperature.(3)Software design and implementation of spread spectrum communication system:Based on the FPGA platform,the software implementation of the modulation part and the demodulation part are realized.Then,the function-verification of the communication system is completed on the Modelsim simulation platform.In the later stage,debugging,testing and verification of the system has completed in the hardware.And the result proves that the function of the system has completed.(4)System debugging and experiment :The communication system is finally coordinated with other sub-components in the projectile firing correct system,such as the missile computer,Beidou navigation,display software,etc.And the performance verification of the system is completed in Chaohu,Anhui.The experimental results meet the design requirements of the system.