Ernest Ofosu Addo, Stefano Caizzone Institute of Communications and Navigation, German Aerospace Center (DLR)

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Satellite navigation has become an indispensable element of modern day life, supporting a wide array of applications in domains ranging from positioning, surveying, and of course, navigation. In recent years, advances in Global Navigation Satellite Systems (GNSS) technology have focused on pushing towards higher precision, targeting subcentimeter accuracy. Reference stations constitute critical elements within the GNSS infrastructure as they provide valuable measurements for monitoring the space segment of the satellite navigation chain. In order to obtain high-quality measurements from these stations, local error sources should be properly characterized and compensated for or minimized. Multipath remains one of the major examples of these error sources. In extreme occurrences, severe multipath can lead to non-usability of GNSS measurements collected from reference station networks, especially in code-dependent applications such as time and frequency transfer. In such cases, expensive post-installation countermeasures may be required. This paper discusses a method for GNSS multipath characterization in challenging installation scenarios, by means of a dual-polarization antenna and its integration in an hybrid measurement-simulation framework. The dual-sense nature of the antenna allows for acquiring auxillary information about the multipath generated by the surrounding objects in the scene and hence a fuller characterization of the multipath conditions is achievable, than what may be acquired using a conventional right-hand circularly polarized (RHCP) reference station antenna. Moreover, the integration of this multipath probe into a digital twin of the real-life installation scenario enables one to predict beforehand, the levels of multipath at the installation point and the effects they induce on GNSS pseudoranges. Thanks to the use of a dual polarized antenna, a plausible range of expected multipath level can be inferred. Validation of the proposed method through field experiments have been reported. Tests with commercial-off-the-shelf geodetic-grade antennas to confirm the efficacy of proposed method have also been shown.