Research On The Fast Acquisition Method Of Beidou Satellite Signals

The rapid expansion of Beidou’s modulation and applications has made the user terminals integrated with adaptive and multi-mode reception functions become a key development area of Beidou applications.Signal acquisition,as the key core of user terminal receivers,has also become a research hot spot.This thesis proposes acquisition methods respectively,according to the characteristics of traditional B1 I and new system B1 C satellite navigation signals,aiming to improve the efficiency of satellite navigation and solve the problems of large computation and high-power consumption in the signal acquisition stage.The main research contents of this paper are summarized as follows:(1)The concept of the Beidou receiver signal acquisition module was researched,simulated the PRN of the Beidou B1 I and the B1 C signal and its correlations,calculated the largest doppler frequency of the satellite of Beidou to a static state receiver,analyzed the principles,advantages and disadvantages of commonly used traditional signal and new system signal acquisition methods.(2)The rapid acquisition method for the traditional B1 I navigation signal was researched.The B1 I intermediate frequency signal simulation model was established with Simulink,and the fast acquisition method combined with data segmentation,frequency compensation and SFT was designed.By analyzing and determineing the parameters of capturing,the proposed capture method is used to compare with the time domain correlation,FFT and SFT acquisition methods using the simulation data.The results show that when the number of downsampling factor and the number of data blocks are over 1,the proposed acquisition method’s effiency is faster than the FFT and SFT acquisition method.(3)The unambiguous fast acquisition method for the new system B1 C navigation signal was researched.Established a B1 C intermediate frequency signal simulation model using Simulink.According to the characteristics of the B1 C signal and signal acquisition equipment’s limit,the unambiguous fast acquisition method combined with PCF and circular shift was proposed.Setting the parameters of capturing,the proposed acquisition method is used to compare with the FFT,ASPe CT and Filtered acquisition methods using the simulation data.The results show that the proposed method can suppress the correlation edge peak effectively and the effiency also increases more than 25% of the ASPe CT and the Filtered acquisition method.(4)The capture performance of the proposed acquisition methods of the B1 I and B1 C signals in the daily real environment is researched.Using OProfile to monitor the consumption of proposed acquisition methods.The capture efficiency will increase with the finer doppler frequency search.In the environment of the maximum dynamic is 140 km/h,the daily adaptability of the proposed capture methods were evaluated,and the results showed that the two proposed methods can work well.