Quality Analysis of Raw GNSS Observation of Google Nexus 9 Smart Tablet Terminal

This paper analyzes and evaluates the quality of the static raw Global Navigation Satellite System (GNSS) observations of Google Nexus 9 tablet in terms of signal-to-noise ratio(SNR), pseudorange residual and phase residual in the open sky. The results show that the SNR of Global Positioning System (GPS), GLONASS observations collected from the tablet is about 10 dBHz lower than normal surveying receiver; pseudorange accuracies of GPS, GLONASS observations are 5.43 m and 11.39 m, phase accuracies are 4.44 mm and 4.99 mm respectively. Compared with the elevation, the SNR is more relevant to the pseudorange residuals and reflects the quality of the observations better. On this basis, a stochastic model of SNR weighting is given and a standard point positioning test is conducted. The positioning precision is 2.74 m in horizontal component and 4.56 m in vertical component which are increased by about 26% compared with the elevation weighted positioning in the open sky.