I. Introduction
The Galileo High Accuracy Service (HAS) is a Galileo service meant to provide high accuracy Precise Point Positioning (PPP) corrections free of charge to its users. HAS was initially conceived to provide satellite bandwidth for commercial PPP providers, but in 2018 the European Commission (EC) decided to make it available to the public in order to promote public benefits of Global Navigation Satellite System (GNSS), particularly in domains with a potentially high societal impact such as the surveying, precision agriculture, and automotive sector [1].