Requirement on the Timing Accuracy of Satellite-Ground Joint Positioning and Inter-Node Time Synchronization

The establishment and improvement of Global Satellite Navigation System (GNSS) has been able to meet the requirements of ordinary users for positioning and navigation. However, the system also has its obvious shortcomings such as susceptibly to interference or spoofing, and because of the spatial geometry distribution, it is difficult to continuously meet the needs of high-precision users. So we pay attention to a kind of satellite-ground joint positioning system along with pseudolites. The contributions are the time synchronization technology between multiple nodes and the accuracy requirement of satellite-ground timing. The conclusions include that the precision of time synchronization can be improved to the nanosecond level by using two-way time measurement at signal level. The requirement of node timing accuracy is mainly affected by the standard deviation of User Equivalent Range Error (UERE), the number of nodes and the Position Dilution of Precision (PDOP) before and after adding pseudolite nodes. Blinding increasing the number of nodes may not improve the positioning accuracy, but will put forward higher requirement for the timing accuracy of the nodes.