Purpose: To understand how to arrange RTK corrections for an INS with included RTK.
Last Updated: July 2020
For Using Physical Base Station
To receive the observation data of a remote base station at the rover receiver of the INS and get the RTK solution, the user can use the STRSVR tool from the RTKLIB package.
Note: RTKLIB is an open source program package for GNSS positioning. RTKLIB can be downloaded via the following link http://www.rtklib.com/. STRSVR tool is provided by Inertial Labs along with the software and documentation.
Below shows the scheme of the STRSVR used for receiving the RTK solution from the base station at the receiver of the INS.
To configure the output streams, select the stream type from the drop-down list at “ (1) Output”, “(2) Output”, or “(3) Output”.
After input and output streams are specified the “Start” button should be pressed to start communication. For details on STRSVR use, please see RTKLIB Manual: http://www.rtklib.com/rtklib_document.htm.
For Using Virtual Base Station
For users using correctional data from a virtual base station instead of a physical base station, their virtual base station will require an initial position sent from the rover as a GPGGA message. This will ensure that the calculated RTCM corrections properly account for the rovers current position in relationship to the virtual base station. The RTK correction tool noted above, STRSVR, works only for correction provided from a physical base station, so it does not work for this scenario.
Instead, the user should go to the “Device options” menu of the INS GUI, navigate to the “GNSS receiver” tab, and select select “AUTO” in the GNSS Correction section as shown below.
When configured to “AUTO” the GNSS receiver of the INS is configured to automatically output GPGGA messages from COM3 of the INS that should then be sent to the virtual base station.
The user can use the tool provided by the any RTK correction provider or the free NTRIP Client by Lefebure that can be downloaded from the link below.
http://lefebure.com/software/ntripclient/
The Lefebure Client will connect to the NTRIP Caster over the Internet, send RTCM correctional data, and send that data to a serial port on the rover.