Research On Acquisition And Detection Technology Of Deep Space Communication Signal

As mankind continues to explore space,the space field has become a hot spot for many countries to contend with.In order to ensure the smooth progress of deep space exploration activities,normal communication between the aircraft and the Earth have become important.Because of the interference that the signal suffers,the signal is easily submerged in the noise.As a key technology,the high dynamic and low SNR signal acquisition in deep space communications is currently a hot topic of scholars.This thesis focuses on the acquisition and detection of deep space communication signal.Firstly,the channel characteristics and the channel factors that cause high dynamic and low SNR of deep space communication signal are introduced.The Doppler effect and signal delay issues are mainly analyzed.Then,three kinds of traditional deep space communication signal acquisition and detection methods are analyzed.Finally,the common performance indicators are analyzed.Secondly,the signal acquisition algorithm based on FFT is studied.This algorithm reduces the number of FFT operations by using the combination of partial matched filter and FFT,and solves the problem of long acquisition time caused by using FFT alone.For this algorithm,there is a problem that the frequency offset estimation accuracy is low,combined with the idea of FFT zero filling and the idea of adding window functions,an improved signal acquisition algorithm is proposed.Combining the spectral correlation function with the ability to concentrate frequency and power,an improved algorithm based on spectral correlation was proposed.Thirdly,considering the high dynamic characteristics of deep space communication signal,the Doppler frequency change rate of the signal is considered.The theory of signal acquisition algorithm based on MFT is analyzed,and the performance of the algorithm is simulated and analyzed.For this algorithm,the time complexity is too high to meet the fast acquisition requirements for deep space communication signal.Therefore,combined with the advantages of delay autocorrelation algorithm,an improved algorithm based on delay autocorrelation is proposed,which reduces the auto multiplication of MFT algorithm.The process reduces the algorithm complexity.Finally,the characteristics of the frequency domain of PN codes are analyzed,and segment code phase correlation is used to simplify the signal acquisition process.By using FFT operation,the time domain problem of signal acquisition is converted into a frequency domain problem,which greatly reduces the computational complexity of the algorithm.For the insufficiencies of the traditional code-phase correlation algorithm,the traditional algorithm is partially improved.Through the simulation and comparison analysis,the tolerance of the improved signal-to-noise ratio is greatly increased.