These observations include not only code pseudorange information but also carrier phase and Doppler GNSS measurements using Application Programming Interface (API). Since then, the scientific community has been paying special attention to GNSS raw observations derived from smartphones. When the first Android Nougat 7 was introduced in May 2016, the GNSS observations could be processed by Android-dedicated applications and recorded into a file. Satellite positioning became a common practice in spreading of location-based applications dedicated for mobile devices, such as mobile phones, tablets or portable navigation systems. The Global Navigation Satellite System (GNSS) chipsets built into the latest mobile phones, along with their miniaturization and reduced production costs, are nowadays a main aim of the electronic mass-market. For fast static surveying mode, the best results were obtained for 20 and 30 min sessions, where average accuracy was also at centimeters level.

In comparison to the fixed reference point position, all three 1 h static session results were at centimeters level of accuracy (1–4 cm). According to the post-processing results, we were able to fix all L1 ambiguities based on Global Positioning System (GPS)-only satellite constellation. Additionally, 1 h sessions were divided into 10, 15, 20 and 30 min separate sub-sessions to check the accuracy of the surveying results in fast static mode. The carrier phase measurements were processed using commercial post-processing software with reference to the closest base station observations located 4 km away. At the same time, a high-class geodetic receiver was used for L1 and L5 signal comparison purposes. For two sessions, the mobile phone was mounted vertically and for the third one-horizontally.

We collected 3 h of raw static data in separate sessions at a known point location. Therefore, we decided to check the performance of carrier phase ambiguity fixing and positioning accuracy results of the latest Huawei P30 pro smartphone equipped with a dual-frequency GNSS receiver. Nowadays, GNSS chips, which are built in the latest smartphones, deliver code and primarily carrier phase observations available for detailed analysis in post-processing applications. Initially, researchers using signals gathered by mobile phones for high accuracy surveying were not successful in ambiguity fixing. Recent developments enable to access raw Global Navigation Satellite System (GNSS) measurements of mobile phones.

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