In 2016, an application programming interface was added to the Android operating systems, which enables the access of GNSS raw observations. Since then, an in-depth evaluation of the performance of smartphone GNSS chips is very much simplified. We analyzed the quality of the GNSS observations, especially the carrier phase observations, of the dual-frequency GNSS chip Kirin 980 built into Huawei P30 and other smartphones. More than 80 h of static observations were collected at several locations. The code and carrier phase observations were processed in baseline mode with reference to observations of geodetic-grade equipment. We were able to fix carrier phase ambiguities for GPS L1 observations. Furthermore, we performed an antenna calibration for this frequency, which revealed that the horizontal phase center offsets from the central vertical axis of the smartphone and also the phase center variations do not exceed 1–2 cm. After successful ambiguity fixing, the 3D position errors (standard deviations) are smaller 4 cm after 5 min of static observation session and 2 cm for long observation session.

中文翻译：

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华为P30智能手机的GNSS代码和载波相位观测：质量评估和厘米级精确定位

2016年，在Android操作系统中添加了一个应用程序编程接口，从而可以访问GNSS原始观测值。从那时起，就大大简化了对智能手机GNSS芯片性能的深入评估。我们分析了华为P30和其他智能手机中内置的双频GNSS芯片Kirin 980的GNSS观测质量，尤其是载波相位观测的质量。在多个位置收集了80多个小时的静态观测值。参考基线和大地测量级设备的观测值，以基线模式处理了代码和载波相位观测值。我们能够修复GPS L1观测的载波相位模糊性。此外，我们对此频率进行了天线校准，这表明水平相位中心偏离智能手机的中心垂直轴，并且相位中心变化也不会超过1-2 cm。成功解决歧义之后，静态观察阶段5分钟后3 cm位置误差（标准偏差）减小4 cm，长时间观察阶段3d位置误差（标准偏差）减小2 cm。