一种改进的A-GPS快速定位方法设计

Study on the Design of an Improved A-GPS Fast Positioning Method

在弱信号条件下,GPS定位技术可能因导航电文无法准确获取而导致定位功能不可用或误差较大,通过A-GPS辅助定位技术解算过程可有效减少捕获定位信号耗费的时间和硬件资源。本文针对传统接收机在未能获取完整的接收机钟差条件下,无法进行A-GPS解算的问题,设计了一种包含5个状态变量的AGPS定位算法,算法仅要求接收机时间误差到达秒级,便可在帧同步与位同步之前实现准确定位,可显著提高接收机的TTFF性能。通过对本文算法进行半实物仿真实验表明,该设计算法在接收机无法获得信号完整时间的情况下能正常工作且具有更短的首次定位时间。

Under weak signal conditions,the inability to accurately acquire navigation messages may lead to unusable or grave errors of GPS positioning functions,while A-GPS-assisted positioning can effectively reduce the time and hardware resources consumed in capturing signals.Hence,to address the issue of conventional receivers’inability to perform A-GPS solution when the complete clock difference is unavailable,this thesis tries to design an AGPS positioning algorithm with 5 state variables.The algorithm can achieve accurate positioning before frame synchronization and bit synchronization when the receiver time error reaches the second level,which can greatly enhance the TTFF performance.In the end,the semi-physical simulation of this algorithm verifies that the designed algorithm works properly and has a shorter first positioning time even when the signal integrity time is not available.