MnCORS VRS users over the past few weeks have been notified of the new server and mount points for logging into for MnCORS RTN in the state of Minnesota. This new server is running the latest Trimble Pivot VRS software and provides a much more stable, and in some cases, more precise platform for VRS surveying.
One of the biggest changes is that on the old server, the corrections were derived from the 2007 positions, and then computed to both the 1996 and the 2011 adjusted values. On the new Pivot platform, the corrections are now derived from the 2011 position, and are computed back for the 1996 and the 2007 adjusted values. Because of this, users will see a slight difference in coordinates when comparing values from the old server to the new.
We have fielded many calls and emails asking about the types of accuracies that can be expected from the server change, and what effect it will have on existing projects. We decided it would be good to run a field test on two known, published MnDOT points using all of the mount points and their associated Geoid models. This test was performed by measuring each point twice with their respective Mount Point/Adjustment at different times of the day. No field calibrations were done, and each measurement was at least 30 seconds long. Below is a summary of our results. The matrix can also be downloaded HERE.
Please keep in mind that these results are for information purposes only, and actual user results will most likely vary across the state. However, for the most part, we are seeing that the new server seems to be more consistent and precise.
MnDOT plans to keep the old server up and running until the end of the year. Our suggestion is that users have dial-in settings and survey styles for both the old and new servers. This will allow users to finish projects with the old system, and start new projects with the new system. We have created a Tech Talk Video on how to do this.
As with any surveying, especially with VRS, it is up to you in the field to use proper procedures and practices to get the most accuracy out of your system. A site calibration may be required to fit local control. See the MnCORS FAQ’s for more information. Also, routine activities such as keeping up with firmware updates in the receivers, software updates for the field controllers, and ensuring your equipment is in good working order and level bubbles are adjusted, are also important things to consider.