Unmanned Systems Technology 022 | XOcean XO-450 l Radar systems l Space vehicles insight l Small Robot l BMPower FCPS l Prismatic HALE UAV l InterDrone 2018 show report l UpVision l Navigation systems

96 Focus | Navigation systems One of them performs relatively typical tasks consistent with the precision accuracy required for general aviation levels of safety. The other would ideally run a receiver autonomous integrity monitoring (RAIM) algorithm, which generates and compares multiple GPS position fixes using redundant signals. The RAIM processor then performs a statistical function to pinpoint a faulty satellite signal. From those readings, a horizontal protection level can be more easily established. At least five satellites must be available to the vehicle antenna for RAIM algorithms to function and detect a fault, while six are required to exclude that fault. For autonomous road vehicles operating in cities, for example, it might be more beneficial to continue using existing systems that have been programmed to work amid skyscrapers and tunnels, tolerating and excluding the known and associated errors. For medium to large UASs in aircraft- dense environments, however – which have been known to integrate as many as five GNSS receivers for autopilot, payload, transponder and redundancy – a dual-processor RAIM GNSS receiver could be the more SWaP-efficient option. In addition to detecting false or misleading signals, and establishing an integrity containment radius around reported positions by cross-checking one another, such receivers can also calculate other critical statistics for ADS-B Out systems, such as positioning accuracy and velocity data. The spread of standards in integrity monitoring, corrections services and multi-constellation capability can only be expected to continue over the next few years. That will have the effect of improving unmanned navigation performance across the most challenging operating environments. Acknowledgements The author would like to thank Joe Carey from Trimble, Christian Ramsey and Ryan Braun from uAvionix, Alexis Guinamard from SBG Systems, Bruno Bougard from Septentrio, Walt Johnson from Inertial Sense, Jakub Maslikowski from VectorNav, Anthony Cole from Swift Navigation, and Miguel Ángel de Frutos from UAV Navigation for their help with researching this article. October/November 2018 | Unmanned Systems Technology AUSTRALIA Advanced Navigation +61 29 099 3800 www.advancednavigation.com.au BELGIUM Septentrio +32 16 30 08 00 www.septentrio.com CANADA Tallysman +1 613 591 3131 www.tallysman.com CHINA ComNav Technologies +86 21 6405 6796 www.comnavtech.com TersusGNSS +86 21 5080 3061 www.tersus-gnss.com FRANCE SBG Systems +33 1 80 88 45 00 www.sbg-systems.com JAPAN Topcon +81 3 3966 3141 www.topconpositioning.com SPAIN UAV Navigation +34 91 657 2723 www.uavnavigation.com USA Hemisphere GNSS +1 480 348 6380 www.hemispheregnss.com Honeywell Aerospace +1 602 365 3099 www.aerospace.honeywell.com Inertial Sense +1 801 610 6771 www.inertialsense.com Linx Technologies +1 541 471 6256 www.linxtechnologies.com Maxim Integrated +1 408 601 1000 www.maximintegrated.com Novatel +1 403 295 4500 www.novatel.com Swift Navigation +1 415 829 2499 www.swiftnav.com Trimble +1 877 728 7623 www.trimble.com UTC Aerospace Systems – Cloud Cap Technology +1 541 387 2120 www.cloudcaptech.com UAvionix +1 844 827 2372 www.uavionix.com VectorNav +1 512 772 3615 www.vectornav.com Some suppliers of GNSS navigation systems