Base-Band Signal Processing Techniques For BDS Software Receiver

BeiDou navigation satellite System (BDS), which is independently researched and developed by China, has the ability of global positioning, navigating and timing services. As the concept of Location Based Service (LBS) gradually known by the public, a variety of embedded navigation products which use position information to provide services are developed in the market and have brought great convenience to people. In this paper, we first focus on base-band signal processing techniques of BDS Software Receiver. Then, an improved signal acquisition algorithm of BDS is presented. Furthermore, the parallel signal tracking is implemented by using the multi-core parallel processing technology, which can optimize the performance of the BDS software receiver. Our work can provide related theory and technique of the software receiver which can perform in different modes and different frequencies.The main contents of this paper are as follows:(1) A BDS software receiver platform, which has the ability of signal simulation, acquisition, tracking, demodulation and position computation, is implemented with C# language.(2) In order to solve the NH code transition problem in Channel I signal in B1 Band (known as B1I signal), an improved algorithm based on parallel acquisition is proposed and simulated. Experimental results show that the improved algorithm can effectively avoid the transition problem caused by the NH code and navigation data, and therefore avoid the related problems caused by transition. The reliability and applicability of the algorithm are improved and successful capture rates of GEO, MEO/IGSO satellites increase respectively from 62%,83% to about 98%.(3) In order to solve the software receiver time delay problem, a B1I signal tracking processing scheme based on C# language is proposed. Multi-channel parallel tracking is implemented by multi-core parallel processing, which can improve the processing speed and reduce time delay of the receiver. Simulation results show that the proposed method can achieve an acceleration-ratio value more than 1.5 and the processing time of tracking signal has been effectively reduced.