Has real time precise point positioning finally hit prime time for surveying applications? The answer is a qualified yes from Gavin Schrock, PLS, Editor of xyHt.
From his article in the August 2019 issue of xyHt.
The dream of being able to achieve survey-grade (2cm horizontal and 5cm vertical) GNSS-derived positions without post-processing, a base, network, radio, or cell service does sound quite appealing. This dream has, slowly over time, become very real—but with certain qualifiers—and unexpected additional functionality for broader applications.
Seven years ago, in a two-part feature, we did a deep dive into the science and state of real-time precision point positioning (RT-PPP). We also speculated on whether such an approach to high-precision GNSS could eventually become a successor to RTK and network RTK (NRTK). We even went as far as predicting that RT-PPP would reach survey-grade performance levels within 5 to10 years, especially in the form of commercial RT-PPP services like CenterPoint RTX.
Equal – Behind – Ahead
We were both right and wrong. Today’s RT-PPP is most certainly survey grade—on par with RTK and NTRK for most applications, slightly behind for other applications—but it also enables you to do things that you could not do with any other high-precision GNSS positioning technology.
A reputed Chinese proverb goes, “People criticize a picture with their ear.” I fell into that trap seven years ago in our feature on RT-PPP, “After RTK” (June 2012: bit.ly/2XlPCIw). An attempt at directly comparing to RTK and NRTK was missing a key point: It is not a matter of better or worse, but different. It is in those differences that the true strengths of RT-PPP can be found.
In 2012 we also examined the early evolution of a commercial RT-PPP service (commercial R&D has made some of the greatest gains for PPP applications and services). In this article, we pick up where we left off in examining that service: Trimble’s CenterPoint RTX. This is not an endorsement of this particular service, as there are several other fine RT-PPP services out there. But because we started years ago looking at this service and its utility for survey-grade uses it makes sense to look at the advancement since then.
Within the RTX family of services there are several different products (based on precision tiers for different applications). Their survey-grade service is called “CenterPoint RTX”; from here forward we will refer to that trademarked service simply as “RTX.”
For the complete article click here.
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