Validation of a European High Accuracy GNSS Service for Cadastral Surveying Applications

Abstract

The European Union H2020 grant project “GISCAD-OV” (Galileo Improved Services for Cadastral Augmentation Development On-field Validation) involves the whole cadastral surveying value chain. The project’s purpose is to design, develop and validate an innovative and cost-effective high accuracy service for cadastral surveying applications, based on GPS + Galileo E6 High Accuracy Service (HAS) and Precise Point Positioning - Ambiguity Resolution (PPP-AR) quick position solution convergence techniques. The focus of this paper is validation of the GNSS positioning. The validation objective involves independent assessment using PPP-AR user processing of real-time GNSS geodetic measurements and corrections for a variety of scenarios. These scenarios include the use of either global or local orbit, clock, bias, atmospheric corrections; or a mixture of both. The global corrections are generated through a global network of receivers, as is typically done for PPP. The local ones are corrections from a Network Real Time Kinematic (NRTK) solution. The scenarios also include the use of early Galileo HAS test signals. Global product results indicate, on average, 10 cm positioning within six minutes at 2-sigma when tested with a significant set of global stations, which can be improved to instantaneous convergence with additional frequencies. Using local corrections in the PPP engine – not seen in literature to-date, results in, on average, 2.5 cm positioning instantaneously at 2-sigma when tested with a large set of European stations within country-wide networks. Similar results are attained with mixed global and local corrections. Galileo HAS test signals are still limited, but preliminary data indicate that the HAS targets are attainable: 20 cm horizontally and 40 cm vertically at 2-sigma. This validation work demonstrates that centimetre-level positioning, required for cadastral surveying, is possible with appropriate corrections and PPP-AR processing. This validation within the wider GISCAD-OV project has the potential to support a wide array of high-accuracy applications.