The Research Of Spread Spectrum Code Rapid Acquistion

With the development of our world aerospace project quickly, satellite navigation position system is becoming a important means of civilian and military activity and is exerting a great effect on the development of our society. Comparing with the traditional DSSS systems, the length of C/A code in beidou project is longer than that of them, which brings us some advantages. however, the longer length of C/A code, the more hardware resource and power it cost.This dissertation commits research on algorithm of C/A code acquisition in satellite navigation position system, and compares the acquisition means of digital differential matched filter (DDMF) with traditional means, and also achieves DDMF with the VHDL language and FPGA platform.To begin with, the dissertation introduces the origin of this project, the content and meanings of its research, and discusses the development of acquisition in inland and oversea. What is more, it also introduces the basic theory and method of acquisition including the character of the m sequence, the Gold sequence, Kasami sequence and some familiar method of acquisition, FFT method, correlated method, matched filter method and all so. it also investigates the technique of DDMF and compares it with other acquisition method. This technique is generally adopted to reduce to the number of multiplication and summation, and the algorithm is better to save unnecessary resource waste. At last the algorithm of DDMF is achieved by the investigation tool of ALTERA company—QUARTUS II and the VHDL language, and its IP core is also achieved which is used not only in the satellite navigation position system ,but also in the long PN code DSSS system. DDMF investigated in the dissertation gives a good way to design the rapid PN code acquisition in the beidou project, and the technology has the definite theory and practice significance.