The Research Of Efficient Direct Acquisition Methods Based On The New Generation Satellite Navigation Signals

Satellite Navigation System was began to rise in the 20th century 70s, which based on the orbit of a satellite constellation, its basic function was to provide real-time and accuratly three-dimensional position, three-dimensional velocity and time parameter information for the sea, land, air and space users around the day. With the rapid development of the modern navigation satellites, it was widely used in the military and civilian fields, resulting in bands crowded, the signal spectrum interferenced from each other, confidentiality reduced. The new generation of navigation signals beautifully solutioned to this problem, such as the U.S. military M code signal and E1 band signal of the European Galileo system all used by BOC (Binary Offset Carrier) modulation scheme. In order to enhance confidentiality, also advanced TDDM (Time Division Data Modulation) spread spectrum mechanism etc. BOC modulated signal's power spectrum had split spectral characteristics, achieved spectral separation, reduced the signal mutual interference; its correlation function was steeper than the traditional way of BPSK, and increased multipath resolution capability. TDDM modulation technique used data signal and no data modulation time division data signals, which improved tracking accuracy.The new generation of navigation signals were applied, the traditional synchronization technology has been unabled to meet its development. Therefore, the synchronization acquisition technologies of the new features signals get more and more attention. Toward the new generation of navigation signals, domestic and foreign advanced a number of acquisition methods, such as double sideband algorithm, single sideband algorithm, Fishman&Betz algorithm, BPSK-like algorithm etc. However, those algorithms had shortcoming for acquisition multi-peaks, signal energy loss greatly, hardware resources required higher etc. Therefore, presenting a kind acquisition method both to maintain accuracy, also improve the speed and timeliness become very important.The BOC and TDDM modulation technology was studied depthly in the paper. Division for its modulation characteristics of the spectrum and autocorrelation function characteristics of multi-peak, through the existing acquisition technologies were studied depthly, two suitable for BOC signal's main lobe fold and main lobe selection optimum algorithm are proposed. TDDM spread spectrum of the BOC and PSK signal characteristics similar to the BOC and PSK signal characteristics is utilized, TDDM spread spectrum of the BOC signal's main lobe fold and main lobe selection optimum algorithm and TDDM spread spectrum of the PSK signal's algorithm are proposed. On the basis of the research, those acquisition algorithms are modeled and designed, through the testing platform, the algorithm for system implementation and testing, compared performance with existing algorithms, and then the acquisition algorithm verified correctness and effectiveness. Finally based on FPGA the BOC signal acquisition algorithms'key modules——data processing module and circle related module are designed for hardware.