Abstract
Modern low-cost electronic devices can achieve high precision for global navigation satellite systems (GNSSs) and related applications. Recently, the pseudo-range and carrier phase have been directly obtained from a smartphone to establish a professional-level surveying device. Although promising results have been obtained by linking to an external GNSS antenna, the real-time kinematic (RTK) positioning performance requires further improvement when using the embedded smartphone antenna. We first investigate the observation quality characteristics of the Xiaomi Mi 8 smartphone. The carrier-to-noise-density ratio of L5/E5a signals is below that of L1/E1 signals, and the cycle slip and loss of lock are severe, especially for L5/E5a signals. Therefore, we use an improved stochastic model and ambiguity-resolution strategies to improve the short-baseline RTK positioning accuracy. Experimental results show that the ambiguity fixing rate can reach approximately 90% in 3 h of observations when using the embedded antenna, while the GPS/Galileo/BDS single-frequency combination is more suitable for smartphones. On the other hand, convergence takes 10–30 min, and the RTK positioning accuracy can reach 1 and 2 cm along the horizontal and vertical directions, respectively, if ambiguity is resolved correctly. Moreover, we verify the feasibility of using a mass-produced smartphone for deformation monitoring. Results from a simulated dynamic deformation experiment indicate that a smartphone can recognise deformations as small as 2 cm.
Highlights
With the development of satellite navigation and positioning technologies, users’ demand for global navigation satellite system (GNSS) equipment with accurate positioning has steadily increased
To fully exploit the advantages of smartphone multi-GNSS signals, namely low cost and ease of use, in this paper, we propose the application of smartphones to dynamic deformation monitoring
The results reported above show that the real-time kinematic (RTK) positioning accuracy of a smartphone can reach 1 cm, suggesting its potential for surveying and mapping applications
Summary
With the development of satellite navigation and positioning technologies, users’ demand for global navigation satellite system (GNSS) equipment with accurate positioning has steadily increased. Developing high-precision applications based on low-cost GNSS equipment has become a dominant trend. Compared with professional GNSS equipment, a smartphone has small size, low cost, and ease of use. The main shortcoming of the smartphone GNSS module is its poor positioning accuracy, with the standard single-point positioning precision being typically approximately 10 m on the horizontal plane [2], greatly limiting its use for professional applications. Users can directly access observations including pseudorange, carrier phase, and Doppler observable from a smartphone. Such data accessibility has greatly contributed to the development of high-precision smartphone GNSS modules toward positioning at the decimetre level or even the centimetre level, expanding their adoption in the GNSS market
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