**Appendix B. Ambiguity Fixing Case Study**

Since ambiguity fixing is essential to achieve highest accuracy results and RTKLIB offers several methods, a brief sensitivity study was conducted utilizing the continuous, instantaneous and fix-and-hold RTKLIB options with the same geodetic-grade antenna type on both, rover and base station (LEIAR25.R3 LEIT). For the sensitivity case study, one day of data from the highest quality antenna, LEIAR25.R3 LEIT was used. The continuous mode estimates phase biases over many epochs. It provides less outliers but when erroneous data are fed into the EKF it may remain over several epochs. The instantaneous method estimates integer ambiguities without constraining the previous (successful) fixes epoch-by-epoch. Fix-and-hold works similar to the Continuous AR, but tightly constrains the validated carrier-phase bias parameters in the next EKF update step. Further details can be obtained from the RTKLIB manual [37]. The results of the RTKLIB processing scheme are shown in Table A1. With 99.69% and 99.70% fixed solutions on L1 and L2 or only 2700 and 1614 float satellite observations on L1 and L2, the fix-and-hold solution performed best in our scenario.


