Abstract
The recent development of the smartphone Global Navigation Satellite System (GNSS) chipsets, such as Broadcom BCM47755 and Qualcomm Snapdragon 855 embedded, makes instantaneous and cm level real-time kinematic (RTK) positioning possible with Android-based smartphones. In this contribution we investigate the instantaneous single-baseline RTK performance of Samsung Galaxy S20 and Google Pixel 4 (GP4) smartphones with such chipsets, while making use of dual-frequency L1 + L5 Global Positioning System (GPS), E1 + E5a Galileo, L1 + L5 Quasi-Zenith Satellite System (QZSS) and B1 BeiDou Navigation Satellite System (BDS) code and phase observations in Dunedin, New Zealand. The effects of locating the smartphones in an upright and lying down position were evaluated, and we show that the choice of smartphone configuration can affect the positioning performance even in a zero-baseline setup. In particular, we found non-zero mean and linear trends in the double-differenced carrier-phase residuals for one of the smartphone models when lying down, which become absent when in an upright position. This implies that the two assessed smartphones have different antenna gain pattern and antenna sensitivity to interferences. Finally, we demonstrate, for the first time, a near hundred percent (98.7% to 99.9%) instantaneous RTK integer least-squares success rate for one of the smartphone models and cm level positioning precision while using short-baseline experiments with internal and external antennas, respectively.
Highlights
The use of survey-grade Global Navigation Satellite System (GNSS) receivers and antennas has traditionally been the only solution to achieve fast and high precision positioning
To further investigate the problematic period for the S20 smartphones in the zerobaseline setup between epoch 13,800 and 25,000, we show in Figure 7a the corresponding L1 Global Positioning System (GPS) and L1 Quasi-Zenith Satellite System (QZSS) DD phase residuals with the smartphones in a lying down position in the left column and in an upright position in the right column
We studied the single-baseline real-time kinematic (RTK) performance while having the smartphones upright and in a lying down position, in a zerobaseline and short-baseline setup, respectively
Summary
The use of survey-grade Global Navigation Satellite System (GNSS) receivers and antennas has traditionally been the only solution to achieve fast and high precision positioning. A few other recent studies [12,13] have further suggested that cm level positioning precision can be achieved in a short-baseline model while using the smartphone internal antennas and a Kalman filter to link parameters in time (multi-epoch model). As a part of our analysis, we will explicitly investigate two setup configurations, namely having the smartphones in an (i) upright and (ii) lying down position, while tracking GNSS signals from both external and internal antennas. The instantaneous smartphone RTK positioning performance is assessed, and the characteristics of the double-differenced (DD) carrier-phase and code residuals are analysed while having the smartphones in an upright and lying down position In this process we will compare the formal and empirical positioning confidence ellipses and intervals, and analyse whether the data follow a normal distribution. An elevation weighting sine-function was used, as employed in RTKlib v2.4.3 [24]
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