Developments on Global Centimeter-level GNSS Positioning with Trimble CenterPoint RTXTM

The first commercial GPS Real-time Kinematic (RTK) positioning products were released in 1993. Since then RTK technology has found its way into a wide variety of application areas and markets including Survey, Machine Control, and Precision Farming. During the last decade several researchers have advocated Precise Point Positioning (PPP) techniques as an alternative to reference station-based RTK. With the PPP technique the GNSS positioning is performed using precise satellite orbit and clock information, rather than corrections from one or more reference stations. Due to its typically long initialization time, efforts have been made by numerous organizations in attempting to improve the productivity of PPP-like solutions. As one of the numerous results of the overall GNSS community initiative, in 2011 Trimble introduced a new technology as a positioning service called CENTERPOINT RTXTM, providing real-time cm-level accuracy without the direct use of a reference station infrastructure. In this paper we will discuss certain aspects of that service, presenting the concepts that are used in order to accomplish certain tasks in the overall system. Furthermore we will present the steps accomplished during the multi-year development of the system, as well as indicate the direction current research work is taking towards new versions of the system.