The Application Of Chaotic Spread Spectrum Sequence In Burst Communication

Spread spectrum communication is one of the core information transmission technologies in digital communication.Spread spectrum communication technology is widely used in military communication because of its ability to resist interference and intercept threats and information concealment and multiple access communication.The communication mode in the burst mode uses the mode of direct expansion and communication,and the information time is short and the sending time is random at every time it is sent.This makes it difficult to intercept the enemy and improve the security of the communication.Therefore,it is often used in military communication But the burst signal in order to correctly receive the signal must be captured,tracking the establishment of synchronization information,due to the special nature of the burst mode of communication,it need to complete a short period of time to capture and tracking process,while the spread code The performance requirements of the larger,which the synchronization algorithm and the choice of spread code put forward higher requirements.In this paper,the technical index of the system is introduced.According to this index,the chaotic sequence is selected as the spread spectrum sequence,verified by MATLAB simulation algorithm based on weighted cascade chaotic sequence with high security,large quantity,excellent balance,self correlation and cross-correlation performance good,then in order to select the superior performance of cascade chaotic sequence by setting each performance index,excluding the performance does not meet the single sequence,and then put forward the burst spread spectrum communication system scheme.Then use the simulation analyse on the performance of spread spectrum use the shaping filter;theoretical research and MATLAB simulation in burst signal acquisition algorithm and carrier and pseudo code tracking algorithm,the main work of the receiver is acquisition tracking and demodulation with matched fast filter correlation to estimate the signal frequency and code phase,the accurate estimation of Doppler frequency using FFT algorithm.At the same time using lead lag loop to get more accurate calculation of loop code phase,after compensating the frequency offset and delay using algorithm in the transmission process,using the differential demodulation.Then based on the design of simulation verification scheme,FPGA technology is used to realize the hardware of the burst spread spectrum communication system.Through the ISE development environment,the hardware is simulated by the simulation software ModelSim to make it meet the timing Requirements,followed by the use of signal source noise oscillograph and other equipment on the hardware function and performance testing,through the test system performance and good work stability,verify that the chaotic burst spread spectrum communication system can be applied in practice.Finally,the paper makes a summary,and puts forward the shortcomings and deficiencies of this paper.Finally,the paper summarizes the whole paper,and puts forward the shortcomings and deficiencies of this paper.