Research Of Capture And Tracking Method For Satellite Navigation Signals On Basis Of The TDDM Modulation

Satellite navigation technology is the technology that using navigation satellite system giving navigation and positioning services for users of land, sea, air and space. It has a wide application in different fields, and has constantly developing with the progress of science and technology and social demand. The traditional satellite navigation signal used BPSK modulation signal. It makes the system of civil and military signals overlapping each other together, and cause frequencies interfere with each other in low signal anti-jamming, and the confidentiality was low. In these cases, a new generation of satellite navigation signal research becomes particularly urgent.New satellite navigation signal achieved spectrum separation, and keep good anti-interference performance with the condition of achieving spectrum sharing. Currently, Binary Offset Carrier (BOC) modulation signal was selected which can meet the above conditions. In order to increase the confidentiality of information, and improve the signal capture tracking precision, Time Division Data Modulation signals based on BOC signal and BPSK signal has become new options of new generation navigation signals. TDDM signal is the focus of this study.In this paper, TDDM-BPSK signal and TDDM-BOC signal based on TDDM modulation are the research objects. It discusses and researches the characteristics of new generation navigation signals, and researches capture and tracking methods. For TDDM-BPSK signal, capture method on the basis of the traditional FFT method, increasing the TDDM branch and the comparison of ordinary pseudo-code branch. odd-even split method is used according to the characteristics of the odd-even modulation. TDDM-BOC signal has characteristics of TDDM modulation and multimodal features on autocorrelation of BOC signal. So we need to considering the two characteristics. In this paper, I used three capture methods, improved FFT method, main lobe superposition method, fractal and reconstitution method. I used the odd-even split method for tracking loop. This research made the subcarrier of BOC signal as a alone loop, to remove subcarrier effects on tracking. These methods are studied the feasibility and validity in theory in the process of TDDMsignal synchronization. The technology researches will provide theoretical reference for development of our BD navigation receiver in the future. These studies also have a great practical significance.