Research And Implementation Of Satellite DSSS Short Burst Fast Demodulation Technology

Small satellite is a research hotspot in today's society and reflects the level of aerospace science and technology in various countries.It has the characteristics of low cost,short development cycle,specific functions and strong resistance to destruction.Short-term burst communication technology has been rapidly developed in military communications with its advantages of concealment,flexibility,and anti-interference,and this small satellite design adopts this communication technology.On the basis of a large number of references,based on a research project of a certain aerospace company,this paper designs a receiver scheme that can achieve fast demodulation of spread spectrum burst signals under low signal-to-noise ratio.An improved PMF-FFT fast acquisition scheme is proposed,which solves the problem of fast acquisition under low signal-to-noise ratio and combines multiple parallel acquisition methods to further shorten the acquisition time.The influence of code phase Doppler and carrier Doppler on the demodulation performance is analyzed with emphasis on longer accumulated time or large Doppler dynamic range.Based on the analysis and simulation of L&R algorithm,kay algorithm and Fitz algorithm,an improved L&R algorithm was implemented to achieve both wide-range and high-precision performance.Finally,the key module engineering implementation scheme is given and implemented by FPCA,which solves the problem of fast demodulation of the spread spectrum signal under the condition of low SNR.In summary,short burst communication technology has high requirements for spread spectrum signal acquisition and carrier synchronization.Therefore,it is very important to design an algorithm that can perform fast demodulation under low SNR conditions.