Accuracy Analysis of a Dual Frequency Gnss Smartphone in Yaounde

Abstract: Geodetic receivers are more demanding in cost and operation than low-cost devices, especially smartphone receivers. Low-cost devices usually have lower positioning accuracy and thus limited to Navigation and GIS applications. With the coming of dual frequency (L1/L5) GNSS smartphones, it is important to diagnose whether their accuracy could meet topographic expectations. Xiaomi 12t smartphone is chosen here with the main objective to measure its accuracy in absolute positioning. By so doing, two geodetic pillars were surveyed one after the other with the smartphone in question. The methodology entails 4h of GNSS observation in PPP static mode at both the control points CP1 and CP2 and the raw data logged by the phone was post-processed online at NRCan/CSRS PPP to obtain the phone’s coordinates. The accuracies were evaluated as absolute discrepancies in phone’s coordinates in planimetric dimension and also using the statistical model from CSRS in evaluating the 95% confidence interval. Apart from the east direction at CP1 that showed a severe discrepancy of 7.954m, the average planimetric accuracy observed in the north and up directions at the two control points using both models in error analysis were found to occur within 2m to 3m interval. The general conclusion was that Xiaomi 12t smartphone is not suitable for topometric and geodetic surveys but very suitable for navigation and GIS applications. The following recommendations were proposed; smartphone accuracy analysis in PPP static using a much longer observation time (at least 10h), determination of precise location of smartphone’s Antenna Reference Point, update of Cameroon Geodetic Network to the ITRF20 realization, similar research with two or more smartphones placed in different directions with use of augmentation systems such as SBAS and NTRIP, similar research with post processing done with a software that enables the treatment of L1 and L5 carrier frequencies of the smartphone and also use of a smartphone that captures signals from both the L1 and L2 carrier wave.