Abstract: To address the limitations of existing satellite selection algorithms for smartphone GNSS pseudorange differential positioning,which include poor adaptability in complex environments and high computational complexity,this paper proposes a novel satellite selection strategy based on the code-minus-carrier observable.The method begins by identifying continuously visible satellites within a predefined time window to form an initial subset.A sliding-window averaging technique is then applied to remove the integer ambiguity component from the code-minus-carrier observations,enabling the construction of a quality evaluation metric.Satellites are subsequently screened using this metric to produce an optimized subset for positioning.Experiments were conducted in both open-sky and obstructed environments using Huawei P40 and Mate40 smartphones.Results demonstrate that in open-sky conditions,the proposed method achieves positioning accuracy comparable to that of full-constellation solutions.Under signal-obstructed conditions,it significantly improves overall positioning accuracy by 20%～25%for the P40 and 30%～47%for the Mate40,relative to the full-constellation approach.The method also exhibits enhanced stability and environmental adaptability in dynamic and challenging scenarios.With its straightforward computational process and ease of implementation,the proposed strategy offers an effective means to improve the accuracy and reliability of smartphone-based GNSS pseudorange differential positioning in complex urban environments.

Key words: satellite selection, smartphone, relative positioning, code-minus-carrier