On the use of between-baseline differenced and instantaneous RTK positioning while using simultaneous GNSS measurements

The single-baseline real-time kinematic (RTK) model has been used over the past few decades for precise positioning. In this contribution, we investigate the performance of the between-baseline differenced (BD) instantaneous RTK model derived by taking the difference between two simultaneously measured single-baseline RTK positions. The BD RTK model can be more efficient to compute since one only needs to take the difference between three baseline coordinates of the receivers. Comparisons are made between the two models while collecting GPS, BDS, Galileo and QZSS data for baseline lengths ranging from 0 to 29 km. We show that re-estimating the single-baseline and computing the BD RTK solutions will give identical results, as long as the satellite positions in view do not become significantly different. Finally, we demonstrate that the success rate for a long BD RTK baseline can increase in comparison to using single-baseline RTK, provided it is determined from shorter baselines.