附加电离层延迟约束的实时动态PPP快速重新初始化方法

传统模式下，由于卫星信号中断等原因导致的实时动态PPP重新初始化问题将严重影响PPP的实际应用效果.针对上述问题，本文提出了一种有效的解决思路，首先设计了电离层延迟变化预报模型，并提出预报信息的定权方法，进而将上述预报结果作为虚拟观测值，联合历元间/星间差分观测数据估计得到周跳参数浮点解，并尝试固定，从而实现PPP快速重新初始化.该方法通过实现电离层预报结果权重的自适应确定，改善了参数估计结果的精度，提高了周跳修复成功率及可靠性.利用不同区域和不同时期的大量观测数据分析表明，周跳修复效果与测站位置、太阳活动及中断时长存在密切关系，当中断时间较短（90 s以内）时，均可以获得较高的成功率，平均达到90%以上，由此验证了本方法的有效性；随着中断时长进一步增大，不同地区和太阳活动情形下的修复效果存在显著差异，纬度越低，太阳活动越剧烈，成功率越低.

Instantaneous re-initialization method of real time kinematic PPP by adding ionospheric delay constraints

In the traditional mode, re-initialization in real time kinematic PPP caused by problems such as signal interruption will seriously affect PPP's performance. A novel method is proposed in this paper to solve the problem. Firstly, an ionospheric predicting model and its relevant weighting method is designed, then floating results of cycle slips is estimated by combining the predicted value and epoch/satellite differenced observations. After that, cycle slip fixing is attempted to achieve instantaneous re-initialization of PPP. Through adaptively adjusting the weighting of the ionospheric prediction results, the accuracy of the estimated parameters are improved, together with the success rate and reliability of cycle slip fixing. Analysis results from different distribution and different epochs reveal that the performance of cycle slip fixing is strongly correlated with station position, solar activity and time latency. Using the proposed method, a success rate higher than 90% can be obtained when the time latency is relatively small (<90 s), which proved the effectiveness of the method. However, the performance differs greatly in different regions and solar activities when the time latency increased. The success rate lowers down with decreasing latitude and stronger solar activity.