Precise Point Positioning (PPP) using Low-Cost and Ultra-Low-Cost GNSS Receivers

Abstract

Few decimetre to metre level accuracy is possible using the cellphone grade GNSS hardware. Current low-cost and ultra-low-cost (cellphone) GNSS receivers have no dual-frequency observables to form linear combination, in-order to account for the ionospheric delay. Global Ionospheric Maps (GIM) are used to mitigate the ionospheric error. Signal-to-noise ratio (C/N0) of cellphone antenna is on average 7.5 dB-Hz low compared to the geodetic-grade antenna which depicts that the quality of the raw observations from cellphone GNSS hardware is of low quality compared to the raw observables from geodetic-grade and u-blox hardware. Raw measurement analysis (C/N0) and post-fit residuals show that signal from cellphones are more prone to multipath compared to signals from geodetic-grade and u-blox receivers. The primary reason for multipath is circular polarized antenna in the cellphones. Irregular gain pattern and poor multipath suppression of cellphone antenna is also the primary reason for the slow convergence of Precise Point Positioning (PPP) solution compared to PPP solution with geodetic-grade hardware. Positioning results from cellphone processing are inferior to the geodetic-grade hardware. However, horizontal and vertical RMS of 37 cm and 51 cm, respectively, is achieved using cellphone.