Abstract
Recent developments enable to access raw Global Navigation Satellite System (GNSS) measurements of mobile phones. Initially, researchers using signals gathered by mobile phones for high accuracy surveying were not successful in ambiguity fixing. 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. 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. We collected 3 h of raw static data in separate sessions at a known point location. For two sessions, the mobile phone was mounted vertically and for the third one—horizontally. At the same time, a high-class geodetic receiver was used for L1 and L5 signal comparison purposes. The carrier phase measurements were processed using commercial post-processing software with reference to the closest base station observations located 4 km away. 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. According to the post-processing results, we were able to fix all L1 ambiguities based on Global Positioning System (GPS)-only satellite constellation. In comparison to the fixed reference point position, all three 1 h static session results were at centimeters level of accuracy (1–4 cm). For fast static surveying mode, the best results were obtained for 20 and 30 min sessions, where average accuracy was also at centimeters level.
Highlights
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
Static coordinate results were computed based on carrier phase observations obtained from the OPNT permanent station (4 km away) and compared to the reference position
In the conducted GNSS measurements, a mobile phone was used with the option of data recording
Summary
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. The ability to use additional observations on a second frequency can increase signal availability and enables a higher level of positioning performances and accuracy by simplifying ambiguity fixing using wide-open techniques and corrections of most error sources, introduced mostly by ionospheric refraction This strictly depends on the processing methodology and the current state of the atmosphere. In the case of smartphones, GNSS observations suffer from high measurement noise, atmospheric refractions or multipath, and from anomalies such as duty cycling and gradual accumulation of phase errors Such a problem occurred with GNSS chipsets built in mobile phones, such as the Xiaomi Mi 8 [7,8,9]. This research work demonstrated that it is not possible to fix phase ambiguities and to reach cm-accuracy in real-time, mostly due to the low quality of GNSS raw measurements collected by a mobile phone. RINEX data, we analyzed the signals, the quality of carrier phase observations and single-base results according to according the nearesttoGNSS reference station
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