Research On Long PN Code Fast Direct Acquisition Algorithm Of Beidou Inter-satellite Link

As a global satellite navigation system, beidou is independently worked and developedby China.Among which the inter-satellite link technology represented by inter-satellitemeasurement and inter-satellite communications not only plays an important role inimproving the viability of the navigation satellite constellation, but also figuresdevelopment direction for the next generation global satellite navigation system. Thespread-spectrum communication technology is often employed for physical layer signalsystem among the navigation satellite link. However, it is very challenging to obtain one ofsuch key technology acquisition under that complex environment.This paper aims to study the long PN code and direct acquisition algorithm under thedirect sequence spread spectrum system. Firstly, by analyzing the environmentalcharacteristics and functional requirements among navigation satellite link, it develops adirect sequence spread spectrum system which adopts long PN code. Secondly, on theresearch of direct spread spectrum system principles and characteristics of long PN code,mainly the principle of pseudo-code acquisition algorithm, it lays a foundation for studyinglong PN code acquisition technology. Thirdly, after the analysis and comparison of the longPN code direct acquisition algorithm at home and abroad, it focuses on the two key issueshow to reduce the long code acquisition time and resource consumption. Finally, on thebasis of learning and absorbing domestic and foreign long PN code acquisition technology,according to the features of weak signals, large dynamic, high data rate, and the short-timeburst communication among the navigation satellite link, it proposes a new long PN codedirect acquisition algorithm which is based on FFT. The new algorithm optimizes andimproves the correlation algorithm, search strategy, sampling rate conversion algorithm,signal accumulation algorithm, dynamic compensation algorithm and judgment algorithm.At the end of the paper, theoretical analysis and simulations have verified the validity andaccuracy of the proposed algorithm.