The Key Technologies Of The High-Dynamic Carrier Tracking Loop In GNSS Software Receiver

Global Navigation Satellite System(GNSS) is a symbol of space powers, which represents the technological and scientific level and brings tremendous military and economic benefits. The Chinese BeiDou satellite navigation system was announced to be able to initially operate in 27th Dec.2011. The application of the Beidou system brings an important development chance to the research on GNSS receiver. China has carried out a series of incentive policies and measures to encourage the research on relative core technology with independent intellectual property.In order to improve the performance of GNSS receiver, researches have been done in various directions. The paper focuses on the key technology of high-dynamic carrier tracking loop. High-dynamic mainly refers that the receiver has higher velocity and acceleration. In the high-dynamic environment Doppler shift makes the carrier generate large shift, which affects the stability of the carrier tracking loop. Especially when the carrier velocity exceeds the dynamic range of the loop, the receiver cannot work normally.As the high-dynamic receiver is mainly used in the high-end field such as military and space, and the western developed countries restrict on exporting the relative technology to China, lots of research results are remain confidential. Now, China is encouraging the deep research in this field. Therefore, the paper has both theoretical and practical applications.The research consists of the following aspects:(1) We propose the concept of effective operating bandwidth in order to measurably describe the dynamic range of carrier tracking loop. And we find the theoretical upper bound of the effective operating bandwidth in the loop and give the mathematical model of the upper bound. This discovery provides theoretical basis for the allowable maximum Doppler shift transition in the high-dynamic environment.(2) In order to raise the velocity of tracking Doppler shift in the loop, we propose a carrier loop design based on the theory of self-adaptive gain control and we give the corresponding self-adaptive control algorithm. The simulation results prove that the design can maximumly optimize the Doppler shift in different extent, which raise the response speed of the loop. Thus the high-dynamic tracking performance of the loop can be enhanced.(3) We put forward a novel Doppler-Parameter detection algorithm based on short-term iteration and give a new tracking loop design based on the algorithm so as to improve the capability of estimating Doppler shift. The simulation results show that only a few phase error measurements and a classical frequency digital filter are required to estimate the high-order transitions of Doppler shift. As a result, the loop is capable of estimating the short term of the Doppler shift, which achieves tracking carrier in the high-dynamic environment.(4) We give a self-adaptive Kalman filter algorithm by introducing Doppler-Parameter detection algorithm to optimize the traditional Kalman filter and using fuzzy control to self-adaptive adjust the observed noise matrix. It can improve the tracking accuracy and reduce the noise while enhancing the high-dynamic performance. The simulation results prove that the algorithm can optimize the filter for the random noise series and improve the estimation accuracy for each order transition of Doppler shift. Therefore, the tracking performance of the carrier loop in the high-dynamic environment can be improved.Based on the above theoretical research and design, we adopt Spirent GSS8000 simulator and practical GNSS signal to build the software receiver platform. Through a lot of simulation experiments, we get ideal results. This research in this paper provides a theoretical and technical basis for the development of GNSS software receiver with high-dynamic performance.