New GNSS precise positioning by mobilephones

In Android Release N (“Nougat”), Google introduced APIs giving access to GNSS raw measurements from android smartphones. After this announcement, users will be able to log GNSS raw measurements such as GPS satellite information (C/No, azimuth, elevation if a particular satellite has been used in the PVT), NMEA sentences and PVT solution with the proper time stamp. This can open many possibilities for the single-frequency GNSS receivers, also called low-cost GNSS receiver, integrated in smartphones. An opportunity to do better and complete research with GNSS raw measurements from the single-frequency GNSS receivers can improve the accuracies for smart mobile devices. Tens meters accuracy could be enough for most of daily navigation purposes; however, it could be better to increase it for some particular cases: usages needs higher accuracy (decimeter of accuracy) like navigation for impaired people. In this aspect, mainly, the research investigates assessment of kinematic and short session static accuracies with single frequency low-cost receivers. Additionally, shares what kind of difficulties are faced, how good the results are evaluated, when the single-frequency GNSS receiver raw measurements are processed and analyzed with well know software packages for geodetic post-processing. To explain in detail, in the research, accuracy assessment of relative static point positioning is practiced for U-blox LEA-4T. U-blox is a single-frequency GNSS receiver that measures the pseudoranges with the C/A code only. For the research, U-blox data quality is investigated for short sessions. In this aspect, the research contains the processing and analysis of static positioning for short time periods with U-blox. Besides, RTKLIB has been tested for processing the U-blox data in short static sessions. Then, Samsung Galaxy S8 is studied as low-cost single frequency receiver with kinematic, single point positioning, DGPS and static point positioning approach. In order to log desired data in android smartphone, OruxMap, GNSS Logger, Geo++ RINEX Logger and RinexOn applications are tested. Estimated point positions in real-time by Samsung Galaxy S8 chipset from API Level 23 and estimated point positions by RTKLIB post-processing from API Level 24 are analyzed in detail. One of the major challenges to reach better accuracies in the research comes from short period of time (5 – 10 minutes) surveys; therefore, experiments are performed with short static sessions with mobile devices. For accuracy assessment, one reference network with stop-and-go surveying technique, one reference trajectory with kinematic surveying technique were established surveying them with geodetic receiver Leica GRX1200.

Con Android Release N ("Nougat"), Google ha introdotto API che consentono l'accesso alle misurazioni grezze GNSS dagli smartphone Android. Gli utenti saranno quindi in grado di registrare le misurazioni grezze GNSS, le frasi NMEA e la soluzione PVT con il timestamp corretto. Ciò può aprire molte possibilità per i ricevitori GNSS monofrequenza, chiamati anche ricevitori GNSS a basso costo, integrati negli smartphone. Una ricerca completa sulle osservazioni grezze GNSS dai ricevitori GNSS a frequenza singola può migliorare l'accuratezza dei dispositivi mobili, che attualmente non soddisfa i requisiti di alcune applicazioni di navigazione, come la navigazione per persone con problemi di vista. In questo aspetto, principalmente, la ricerca riguarda la valutazione delle precisioni cinematiche e statico veloci con ricevitori a singola frequenza. Per spiegare in dettaglio, nella ricerca, si è dapprima testato il posizionamento statico con U-blox LEA-4T, un ricevitore GNSS a frequenza singola con antenna esterna. Per la ricerca, la qualità dei dati U-blox è studiata per brevi sessioni. Quindi, il chipset GPS di Samsung Galaxy S8 è stato studiato come esempio di ricevitore a singola frequenza in uno smartphone: per registrare i dati sono stati testati OruxMap, GNSS Logger, Geo ++ RINEX Logger e RinexOn. Le prestazioni del chipset sono state testate per applicazioni di point positioning, differenziale sui codici e differenziale sulle fasi.