PPP RTK and inter system biases: the ISB look up table as a means to support multi system PPP RTK
PPP RTK has the potential of benefiting enormously from the integration of multiple GNSS/RNSS systems. However, since unaccounted inter system biases (ISBs) have a direct impact on the integer ambiguity resolution performance, the PPP RTK network and user models need to be flexible enough to accommodate the occurrence of system specific receiver biases. In this contribution we present such undifferenced, multi system PPP RTK full rank models for both network and users. By an application of \mathcal {S}$S system theory, the multi system estimable parameters are presented, thereby identifying how each of the three PPP RTK components are affected by the presence of the system specific biases. As a result different scenarios are described of how these biases can be taken into account. To have users benefit the most, we propose the construction of an ISB look up table. It allows users to search the table for a network receiver of their own type and select the corresponding ISBs, thus effectively realizing their own ISB corrected user model. By applying such corrections, the user model is strengthened and the number of integer estimable user ambiguities is maximized.
Journal of Geodesy