Capture Algorithm Research Of Baseband Signal In Beidou Receiver

"Beidou-1"Navigation Satellite Test System on regional satellite navigation as the goal established the first satellite radio system of China, which started prelude for China's modernization construction of Compass Global Position System."Beidou-1"system privdes swift positioning, real-time navigation, brief communications and precise timing services, mainly in China and its circumjacent territory, which takes a significant economy and social significance role for meeting the national economy, national defence construction requirement. Baseband signal processing modul is the key of receiver performance, as well as the spread-spectrum code synchronization and tracking is the key technology of it. Researching Beidou PN capture technology is the basis for the work to implement navigation receivers.The thesis's primary mission is capture algorithm research of baseband signal in Beidou receiver. Firstly, the thesis described background to carry out research projects. And then, the thesis introducted navigation principle of "Beidou double-star Positioning" and satellite signal structure, and gave a simulation model of the satellite signal.In the next section, the thesis proposed the Beidou receiver solution of digital baseband processing system, firstly. And then the thesis analyzed carrier-frequency offset estimation algorithm based on separation of carrier and code Phase, elaborately. With this algorithm, it could quickly capture PN code phase and Doppler frequency offset adopting FFT algorithm. FFT for fast convolution correlation and the combination of FFT and circular convolution algorithm can effectively improve the PN code acquisition velocity and precision.Finally, the combination of required detecting probability and false alarm probability of the Beidou receiver, performance in low signal to noise ratio, to improve detection SNR through non-coherent integration and coherent integration. Application of "Binary Accumulation" criteria obtain detecting performance the receiver system required in a lower SNR.In the thesis, I simulated the design scheme and key algorithm of Beidou receiver based on Matlab program, and gave performance analysis and simulation results of the proposed satellite signal acquisition algorithm and signal detection method. Theoretical analysis and simulations shows that the scheme and algorithms are available, and achieved the desired design goals.