CroCoord v1.0—An Android Application for Nearly Real-Time 3D PPP Multi-frequency Multi-GNSS Static Surveying Using Smartphones

The hardware of new-generation smartphones enables navigation, positioning and surveying (NPS) using Global Navigation Satellite Systems (GNSS). Moreover, unprecedented progress has been made in the last few years related to the accuracy and reliability of smartphone NPS giving three significant changes: (1) accessing raw code and carrier GNSS measurements; (2) collecting multi-frequency measurements and; (3) collecting measurements from multiple global satellite navigation constellations (GPS, GLONASS, Galileo, BeiDou-3). We developed CroCoord v1.0—an Android application for nearly real time PPP multi-GNSS static positioning and surveying. An application offers increased accuracy compared to other solutions given by smartphone applications, as it uses PPP GNSS post-processing method to correct collected multi-frequency multi-GNSS measurements for several sources of errors, including ephemeris, ionosphere, troposphere, satellite clocks, etc. The positional accuracy of static surveying using smartphones (including also our application) was tested on one control test site with three GNSS processing methods (SPP, PPP, and DGNSS). The positional accuracy of CroCoord in PPP mode is below 1 m and may even reach 0.5 m for an observation period longer than 1 h. The positional accuracy of CroCoord is higher for 65% compared to the accuracy obtained by default processing routines of android smartphone. Furtherly, the combination of smartphone and permanent GNSS station data (a network-DGNSS mode) reached the possibility to obtain the accuracy of 9 cm for 2-h static session. Our results confirm the enormous potential of smartphone multi-frequency multi-GNSS measurements in all civilian and professional applications which have benefits from increased positional accuracy.