Introducing Ambiguity Resolution in Web-hosted Global Multi-GNSS Precise Positioning with Trimble RTX-PP

In the middle of 2011 Trimble introduced the CenterPoint RTX real-time positioning service providing centimeter accurate positions for real-time applications. This service relies on the generation of precise orbit and clock information for GPS and GLONASS satellites in real-time. Support for the first Japanese QZSS satellite was recently added to the system. While existing PPP systems are available via web access today, the RTX-PP is unique with respect to the support of QZSS signals, the ability to resolve carrier phase ambiguities and the associated convergence performance. The CenterPoint RTX service is providing real-time precise GNSS positioning for specific markets such as Precision Agriculture, Survey and Machine Control. The delivery of corrections for the receivers in the field occurs either via satellite link or internet connection. This paper introduces the new Trimble RTX Post-Processing (RTX-PP) service which is running in the cloud providing absolute position estimates in the well-defined reference frame ITRF2008 using GPS, GLONASS and QZSS observations. The service is available as a web service as well as through a variety of Trimble office software products. The achievable horizontal and vertical accuracy level of RTX-PP can be better than one centimeter with one day of measurement data. Since the convergence time of the solution is well below one hour, however, the delivered horizontal positioning accuracy is typically better than 2 centimeters after only one hour. The paper presents the technology behind RTX-PP and discusses the different applications the service addresses. These include but are not limited to the establishment of precise reference frames with a well-defined datum; especially in areas without sufficient infrastructure, monitoring of the positions of GNSS reference stations for quality assurance purposes and tectonic motion and monitoring of deformation and subsidence. Time series of position estimates will be presented to demonstrate the achievable accuracy in a variety of scenarios, including static and kinematic cases.