An Improved Method for PPP Time Transfer with Forecast Clock Model and Performance Evaluation

In traditional PPP time transfer, the receiver clock offset is estimated as white noise (WN) and the atomic clock frequency characteristics are ignored, which is challenging to meet the needs of current high precision time-frequency users. To improve the accuracy and frequency stability of the current PPP time transfer method, a PPP time transfer based on the forecast clock (FC) model is proposed in this paper. Relevant experiments were conducted for the model and the experimental results showed that: (1) The selection of sliding window size in the FC model is recommended to be set between 0.5 and 1 h. (2) The time transfer accuracy and frequency stability of the FC model are both improved compared to the WN model. For time transfer accuracy, the FC model is more than 20% better than the WN model; For frequency stability, the FC model not only improves up to 54% compared to the WN model but also improves more than 8% overall, and the short-term and long-term stability is better than IGS final products.