Performance analysis of differential and relative global navigation satellite system position estimation

Abstract

The human being has been concerned with the knowledge of his position on Earth’s surface since the dawn of civilization, whether to map the environment, delimit borders, or assist in the

navigation. With the beginning of the space age and, consequently, the advent of new techno- logies, it was possible to develop positioning and navigation systems with global coverage in a

broad range of accuracy and cost. Agriculture is one of the application fields that benefited from navigation services provided by Global Navigation Satellite Systems (GNSSs), especially the Precision Agriculture (PA), which aims at identifying and treat spatial and temporal diversity in the field to reduce costs and increase production. Precision agriculture is already a reality for large landowners who can use several systems that provide high accuracy positioning services, such as Differential (DGNSS) and Relative (RGNSS) techniques, Real-Time Kinematics (RTK)

positioning techniques or Satellite-Based Augmentation Systems (SBAS). Small and medium- size farmers, in turn, have restricted access to such technologies due to the high cost of the

required equipment and subscriptions. An alternative to the presented problem is to use GNSS receivers of the Brazilian Network for Continuous Monitoring of GNSS (RBMC) as reference stations to compute differential and/or relative position corrections, and then, obtain, at no costs, more accurate position estimates, since RBMC data is freely accessible to the public. The main contribution of this work is a performance analyses of DGNSS and RGNSS approaches, with the objective of achieving position accuracy at a submetric level. An analysis of the spatial and temporal degradation on RGNSS positioning estimates is presented based on real GNSS data collected from stationary high-cost GNSS receivers belonging to RBMC. Experimental results show that submetric horizontal positioning is attainable at 68% of probability (1σ) with

reference stations distanced up to 2100 km and communication latency up to 1500 s. Additi- onal results, considering a moving rover equipped with low-cost GNSS receiver, demonstrate

position accuracy below 1.5 m for baseline distances between receivers of about 1500 km and latency up to 3000 s.