GNSS receivers and corrections: evaluation and application in precision agriculture

This thesis was carried out following an internship at Wirail. The core business of this company is the development of control units for the telemetry of moving vehicles. The control units I worked on are equipped with modems for internet connection, a microcontroller, a touchscreen display, and a GNSS receiver. Given the rapid evolution of precision agriculture, the aim of the thesis is to assess the quality of the GNSS receiver. The one installed in the control unit is a GNSS receiver capable of operating in SBAS (differential) mode, achieving an accuracy of 1 meter. However, today there are receivers that implement different correction techniques, reaching centimeter-level accuracy. In the first part of the thesis, possible alternative solutions are explored. The alternatives are between the RTK system and the PPP system. The former requires a fixed base that must be precisely located, which will serve as the reference for calculating errors. The latter replaces the fixed base with a network of pre-installed bases, from which corrections can be received. The advantage of the second solution is that corrections can be received via an internet connection without necessarily having a base nearby. On the other hand, having a base close to the work area allows for better accuracy. This thesis evaluates the performance of a solution based on the PPP system. The evaluation of the PPP mode was carried out using an evaluation board. Static and dynamic tests were conducted to analyze the performance of the GNSS receiver. The corrections were obtained by connecting to the SPIN3 GNSS network: a free service available in Piemonte, Lombardia, and Valle d’Aosta. Given the favorable outcome of the tests, the new GNSS receiver was installed in the control unit. At this point, two applications were developed to assist the operator in performing precision tasks. The first aims to monitor operations to be performed at the end of the row. The second helps the operator follow a predefined straight path.