Research On Weak Signal Acquisition In B1 Band For BDS ?

With the increasing demands of positioning under the circumstances of special conditions such as indoor, urban environment, navigation signals between the satellites and the users are affected by multipath effect, shadow fading, noise and some other factors in the transmission process, it is difficult for common BD ? receivers to capture the signals. Hence, weak signal acquisition for BD ? has been the researching focus of navigation and positioning system.This thesis emphases the weak signal acquisition in B1 band for BD ?. Based on the description of BD ? structure, the traditional coherent integration, non-coherent integration and coherent-differential coherent integration are presented in detail. Then the impact of data bit transition on three types of integration is analyzed. The simulation experiments of different algorithms lead to different performance analyses, and the three kinds of algorithms are compared in this thesis.Finally, a modified parallel acquisition method to improve the detection probability of BD ? signal is proposed in this thesis. Based on the non-coherent acquisition algorithm, the algorithm makes some changes to the detection method, and the detection probability of the system is improved. The influence of noise fluctuation on threshold can be avoided without the analysis of noise distribution in real time, but the detection of multiple stores and statistics can also affect the acquisition speed. Through the comparison of simulation experiments, the proposed algorithm can effectively improve the detection probability of weak signals. As a result, this approach yields higher acquisition sensitivity up to 3-4d B-Hz compared to the traditional method.