This work assesses the performance of uncalibrated phase delay (UPD) products at different scales in multi-Global Navigation Satellite System (GNSS) precise point positioning ambiguity resolution (PPP-AR). Two sets of wide-lane (WL) and narrow-lane (NL) UPD products were estimated and generated using the Multi-GNSS Experiment global station network and the Heilongjiang regional station network. A systematic evaluation assessed the stability, precision, and impact of these products on positioning performance. The results show that regional UPD products surpass global ones in accuracy and stability, mainly due to denser measurement stations and reduced unmodeled errors, with a notable advantage in NL UPD stability. Conversely, global UPD products demonstrate broader observation coverage and greater applicability, effectively mitigating regional errors and exhibiting superior WL UPD stability. The positioning experiments confirm that both global and regional UPD products enable high-precision PPP-AR positioning within the user domain. However, for regional users, PPP-AR based on regional UPD products delivers superior performance. In single-system mode, the BeiDou Navigation Satellite System (BDS) with regional UPD products achieves an average convergence time of 13.6 min, a 23.6% improvement over the global solution. BDS positioning accuracy is comparable to GPS, with marginally better vertical performance. Furthermore, the integration of multiple systems significantly enhances positioning performance. The GPS, Galileo, and BDS (GEC) combination with regional UPD products reduces the convergence time to 7.3 min, a 24.7% improvement over the global solution. After 15 min of convergence, the horizontal and vertical positioning accuracies reach 3.2 and 3.6 cm, outperforming global UPD accuracies of 4.3 and 4.6 cm. These findings offer critical insights into optimizing high-precision regional positioning services and emphasize the benefits of regional UPD products and multi-GNSS integration.
Xu et al. (Fri,) studied this question.