Posicionamento por ponto preciso em tempo real para receptores GPS de simples frequência: um estudo de caso sobre a América Latina com foco em veículos agrícolas conectados

Abstract

Global Navigation Satellite Systems (GNSS) can be used in various areas of knowledge, such as locating people and vehicles, precision agriculture or even defense systems and air traffic control. Currently, there are several positioning techniques that can be applied to such systems, each with its own particularities and limitations. Therefore, it is relevant to study alternative techniques that seek to improve positioning accuracy, such as the Precise Point Positioning (PPP) technique, which was originally created for post-processed applications (PP-PPP) based on dual receivers. frequency (DF), but which can currently be used in real-time applications (RT-PPP) based on single frequency (SF) receivers. The use of SF receivers reduces the implementation cost in relation to solutions that use DF receivers, however this technique requires that corrections be applied to the observables of a GNSS receiver in order to individually mitigate the components of the so-called “common mode errors” (CME ). Such RT-PPP corrections are provided by

specialized agencies, such as the International GNSS Service (IGS), the Facultad de Ciencias As- tronómicas y Geofísas (FCAG), of the Universidad Nacional de La Plata (UNLP), the Bundesamt

für Kartographie und Geodäsie (BKG), among others. Therefore, the objective of the present work is to investigate the format in which each correction is generated, as well as to define suitable algorithms for implementing a submetric positioning solution via SF RT-PPP using particularly the Global Positioning System (GPS). To achieve this objective, this work begins with a review of the literature in the area of GNSS, comprising the characterization of positioning methods, followed by an analysis of aspects related to the nature of the RT-PPP corrections provided by IGS and FCAG-UNLP, as well as the need to apply additional corrections to the RT-PPP solution. Real-time stationary GPS data is then collected from high-quality receivers via the BKG Ntrip Client (BNC), designed by BKG, as well as IGS RT-PPP corrections. In parallel, ionospheric corrections made available by the FCAG-UNLP server are also collected. After data collection and computational simulations, experimental tests are proposed in order to evaluate the performance of the estimation techniques investigated in relation to: (a) the entire region covered by the current ionospheric correction service provided by FCAG-UNLP, the namely, Latin America, extending to the Caribbean and the Antarctic Peninsula; (b) dynamic conditions of the receiver, collected from tests with urban and agricultural vehicles in motion; (c) different empirical tropospheric compensation models and different mask angles for visible satellites; and (d) compliance with various positioning requirements applicable to connected vehicles. As the main contribution of this dissertation, it is shown that the RT-PPP solution with GPS SF receivers based on ionospheric products from FCAG-UNLP, tropospheric model from University of New Brunswick (UNB3), and mask angle of 16 degrees, provides better positioning accuracy, especially in the horizontal channel, when compared to the corresponding solution based exclusively on IGS products.