## 5 Conclusions  
A novel weighting and exclusion function has been proposed and demonstrated using real data collected within the framework of the FANTASTIC project. The technique uses the RHCP and LHCP components of a 2 pol antenna. Depending on the difference between the strength of these two components, the technique either excludes or weighs the measurements. We have demonstrated the detection of NLOS and the improvement of removing these signals from the PVT computation. For the first time, we have assessed the effects of this exclusion into the RTK phase-based positioning. In general, we can conclude that exclusion is beneficial for RTK positioning because the RMS 3D error is reduced. It is worth noting, though, that this improvement is dependent on the scenario. Actually, the improvement depends on the NLOS propagation (i.e., small or large delay) and the quality of the remaining signals and user-satellite geometry. It is for the above reason that, as indicated by the obtained results, the exclusion function is very useful in urban environments or those environments  
Figure 17: Relative frequency of the phase error measurements as a function of the RHCP to LHCP ratio.  
with large delay NLOS propagation and/or scenarios in which most signals have good visibility and there are few signals with severe multipath. So, the improvements gained with the exclusion function come from the exclusion of NLOS measures, this is something that cannot be achieved with traditional mitigation techniques [1; 2], therefore the large improvements experienced in the urban scenario.  
As already stated, the results presented in this paper, show the application of the concept of 2 pol exclusion into RTK positioning. This is in contrast to [12], which applies a weighting function with a 2 pol antenna for precise point positioning. We have also proposed a weighting function with a good fitting between the used model and the measured data. Notwithstanding, this fitting was not translated into a valuable improvement of the PVT solution. The reason is that in RTK phased-based positioning the phase measurements used for the PVT computation are accurate measurements with similar errors (of the order of few cm). Then, the weights provided by the weighting function will be similar, thus the effects on the PVT solution will be negligible. In summary, we have proposed a novel technique to mitigate the effects of multipath into the PVT solution. The technique can be easily implemented in any receiver with a two-antenna input feed, allowing the use of a 2 pol antenna. This is in contrast to traditional techniques, which are usually too complex to be implemented in practice. Moreover, the proposed technique is useful for dynamic scenarios without needing any additional component such as maps or cameras. This is an advantage with respect to those contributions proposing site-dependent techniques. Finally, regarding multi-antenna solutions (best candidates nowadays), our contribution provides an advantage in terms of dimensions. So, the simplicity, robustness, and size of the proposed solution is expected to leverage the application of precise GNSS positioning in many professional applications in which current GNSS accuracy is insufficient.  
Conceptualization, W.D.W.; Data curation, A.T.-C.; Formal analysis, D.E.-R.; Funding acquisition, B.B. and J.-M.S.; Investigation, D.E.-R. and A.T.-C.; Methodology, D.E.-R. and G.S.-G.; Project administration, B.B. and J.-M.S.; Resources, A.P.; Supervision, J.A.L.-S. and G.S.-G.; Validation, W.D.W. Writing--original draft, D.E.-R.; Writing--review and editing, G.S.-G., W.D.W. and A.P.  
This work was partly supported by the Spanish Grant TEC2017-89925-R and by the European GNSS Agency (GSA) under the FANTASTIC project (GSA/GRANT/01/2016) and the APC was funded by the FANTASTIC project.  
The authors would like to thank GMV and Instituto Superiore Mario Boella (ISMB), as part of the consortium that carried out the FANTASTIC project, for their valuable support.  
The authors declare no conflict of interest.