基于GP2000的GPS软件接收机设计及捕获算法实现

Design of GPS Software Receiver Based on GP2000 and Realization of Acquisition Algorithm

结合GPS（Global Positioning System）信号的下变频过程，设计了一种基于GP2015和GP2021芯片的低成本GPS软件接收机（software GPS receiver）。讨论了捕获算法的信噪比和耗时问题，针对并行码相位捕获算法信噪比低、连贯积分捕获算法耗时长的问题，采用了非连贯积分捕获算法。在信号跟踪算法中，采用锁频环和锁相环相结合的方式。仿真结果表明所选捕获和跟踪算法能够实现信号的捕获、跟踪及导航电文的解调。通过仿真发现现有的捕获算法在改善信噪比时会增加捕获的耗时，为GPS算法的改进提供了一个方向。

According to the process of the down converting of GPS （Global Positioning System） signals, a GPS software receiver based on GP2015 and GP2021 is designed. The Signal to Noise Ratio （SNR） and time expense of acquisition algorithms are discussed. Considering the low SNR of the parallel code phase search acquisition algorithm and the too much time expense of the coherent par- allel cold phase search acquisition algorithm, a noncoherent integration acquisition is proposed. Both Frequency Locked Loop and Phase Locked Loop are used in tracking algorithms. Simulation results show that the proposed acquisition and tracking algorithms can accomplish the acquisition, tracking and demodulating of navigation data. Through simulation, we discover that existing acquisition algorithms will lead to increasing the time expense while improving the SNR, which will provide assistant to improve the GPS algorithms