Evaluación del posicionamiento preciso GNSS-NRTK en los límites fronterizos de redes activas regionales en el SW y SE de la Península Ibérica/Testing precise GNSS-NRTK positioning at the limits of regional active networks in SW and SE of the Iberian Peninsula

RTK positioning reduces the effects of orbit errors and ionospheric and tropospheric refraction by forming double-differences between the phase observables. These effects grow with increasing baseline length, however, the use of corrections generated in real-time from an active GNSS network allows the distance-dependent errors to be reduced, increasing the reliability of the system and the accuracy of realtime positioning. In border regions, the accuracy and precision of NRTK positioning tend to degrade at the limits of the network where the rover is not surrounded by reference stations and the NRTK corrections are extrapolated. The coherence between the reference frames propagated to the users by neighboring active networks should be also checked. In this study, the test results of post-processed and simultaneous NRTK positioning at test points located in the border areas between Portugal and the Community of Andalusia and between the autonomous communities of the Region of Murcia and the Valencian Community, in the SW and SE of the Iberian Peninsula respectively, are presented in order to analyze the real-time services offered. The analysis is based on four GNSS regional active networks present in these border areas: RENEP, RAP, REGAM and ERVA networks. The results confirm that it is possible to achieve centimetre-scale precision and accuracy with NRTK positioning, even in border regions considering extrapolated NRTK solutions in the limits analyzed.