GNSS-RTK v0.7 retrospective

[gwbres]

Before upgrading to a new, more performant and more sophisticated library, let's retrospect on the performances obtained until then.

Static surveying

GNSS-RTK exhibits very good performances but is limited to static navigation.
The new Nyx-Space V4 framework allows results better than ever.
We support SPP and CPP techniques, true PPP is not yet supported, due to both core library and application limitations.

Here is a snippet from MOJN and Esbjerg SFDI GNSS reference stations static surveying, using GNSS-RTK lib + RINEX-Cli applications.
Red dot was obtained by profesionnal calibration of the GNSS reference marker. Black dot is the final solution obtained by our library.

Evolution of the navigation solution against averaging time.

Until V0.7 we can see that the tool operates correctly under static use case. The navigation filter behaves correctly but needs long term averaging and reaches a natural maximum that remains stable. The approach phase is rather long, considering it consumes about 25% of a day.

3D projection :

The Filter convergence is even more obvious in time domain

Surveying & stations calibration

GNSS-RTK has become a true surveying tool, in the sense it can operate without apriori knowledge, and is therefore, compatible with RTK reference stations calibration

Application to Precise Timing

Starting from late 2023, RINEX-Cli + GNSS-RTK + CGGTTS allows solving precise Temporal product in the form of CGGTTS solutions. It is the same solution as previously demonstrated, but reworked and respecting the CGGTTS specifications and requirements.

This is the so called REFSYS or simply GPST resolved by the RINEX-Cli + GNSS-RTK + CGGTTS combination:

The navigation filter approach is more extreme, both induced by the CGGTTS sensitivity and probably a few errors in its implementation that needs to be corrected. This confirms the correctness of GNSS-RTK, as we can see that the solution is the same of that given Constellation while solving with individual satellites. The +/- 1ns theoretical precision is emphasized.

RTK

True Real Time Kinematics is not supported yet, I'm still working on concluding the SPP/PPP algorithm. RTK is much more simple so, once this topic is concluded, we will rapidly unlock this new option