Nottingham smartphone GNSS Raw to RINEX (NSGRX) Converter: a new smartphone data converter: principles, methodology and experimental evaluation

With the widespread availability of Android’s raw GNSS API, there is a growing demand for reliable tools that convert smartphone GNSS logs into standard RINEX files for post processing. Existing solutions often omit observables, mislabel frequencies, or provide unstable outputs, limiting their use in high-precision applications. This paper introduces the Nottingham Smartphone GNSS Raw to RINEX (NSGRX) converter, a novel Python-based GUI application that overcomes these limitations by producing complete, standards-compliant RINEX files. NSGRX supports GPS, Galileo, GLONASS, and BeiDou dual frequency observations without external dependencies and generates precise pseudorange, carrier phase, and Doppler observables using robust algorithms. In static tests with data from Samsung S23 FE and Xiaomi Mi 11T devices, RINEX files generated by NSGRX achieved fixed solution rates of up to 100% in RTKLIB processing significantly outperforming five existing converters. Importantly, the results show that observation quality (pseudorange, carrier phase) has a greater impact on ambiguity resolution than the number of satellites tracked. Among the converters evaluated in this study, NSGRX was the only tool that consistently generated complete and stable dual frequency RINEX files while preserving the available GNSS observations and associated quality indicators, which contributed to substantially higher ambiguity fix rates in subsequent RTKLIB processing.