Low-cost GNSS receiver in RTK positioning under the standard ISO-17123-8: A feasible option in geomatics

Abstract

GNSS positioning is nowadays applied for surveying and other geomatic applications. Although dual-frequency GNSS receivers are widely used, low-cost single-frequency receivers have been relegated to navigation applications. However, their advantages make them optimum candidates for positioning applications in many scientific areas. To know the precision limits of these measuring systems, the evaluation of the uncertainty of measurement results obtained by them is required. For that, it is recommended to apply standard operating procedures (SOP). The International Organization for Standardization (ISO) published the standard ISO 17123-8 aimed at specifying field procedures to be adopted when determining and evaluating the precision of GNSS field measuring systems in real-time kinematic (RTK). Using this standard, we evaluate the positioning performance of two GNSS receivers, the geodetic dual-frequency Leica GS10 with AS10 antenna using a network RTK solution, and the low-cost single-frequency u-blox NEO-M8P using a single-base RTK solution. Considering the different sources of uncertainty and their influence quantities, the combined uncertainty budget for the dual-frequency receiver gives combined standard uncertainties on the horizontal position at the order of ±2.5 mm and close to ±4.5 mm for the vertical coordinate. In the case of the low-cost receiver, the combined standard uncertainties are close to ±5.5 mm for the horizontal position and ±11 mm for heights. The results indicate that just as the geodetic receiver satisfies the horizontal and vertical sub-centimetric precision limits established for high precision applications, the low-cost receiver can achieve a competitive positioning performance to survey-grade receivers in real-time positioning for short baselines.