March 2023: A paper written by the RNL’s Robert Tenny titled “Robust Navigation for Urban Air Mobility via Tight Coupling of GNSS with Terrestrial Radionavigation and Inertial Sensing” got published in Inside GNSS. “Central to the transportation revolution that will be driven by urban air mobility (UAM) is the problem of robust and secure navigation. Urban environments offer more challenges, such as interference and multipath, when compared to open-sky conditions. As the only positioning system that offers absolutely-referenced meter-level accuracy with global coverage, GNSS will no doubt play a significant role in this revolution. If strengthened against jamming and spoofing, carrier-phase-differential GNSS (CDGNSS), coupled with low-cost inertial sensing, will be nearly sufficient for position, velocity and timing (PVT) needs. But nearly sufficient is insufficient: It is not enough for a UAM PVT solution to offer decimeter-accurate positioning with 99% availability, or even 99.9% availability. UAM will demand that its navigation systems offer decimeter-accurate positioning with integrity risk on the order of 10-7 for a meter-level alert limit and availability with several more 9s than 99.9%.” The publication, selected as the cover story of Inside GNSS+ in March/April 2023, can be found here.