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

88 A part from AUVs when operating underwater, autonomous vehicles depend largely on GNSS technology for navigation and localisation, and the reliability of the former is tied directly to improvements in the latter. GNSS provides critical services for unmanned vehicles, aside from merely outputting position readings. Waypoint- guided navigation for survey mission autopilots, georeferencing systems for photogrammetric applications, and reliable coordinate transmissions for transponders in air traffic integration all depend on GNSS receivers. And as demand for the number and precision of GNSS signals grows, so advances in navigation systems are emerging to meet that demand. Ongoing SWaP optimisation in GNSS technologies generally means more linear RF front ends (the circuits between the antenna and the part of the receiver containing the mixers and tracking loops), which makes them less susceptible to out-of-band interference. Also, Europe’s Galileo, China’s BeiDou and the international GPS L5 constellations are poised to enable greater accuracy and fewer position errors than GPS and GLONASS channels. Multi-frequency A multi-frequency GNSS receiver is one that, as its name suggests, tracks at least two signals from satellites on different frequencies – for example, GPS L1 and L5, which operate using 1575.42 MHz and 1176.45 MHz as their respective centre frequencies. Access to L5 satellites provides many advantages for unmanned vehicles. Rory Jackson reports on how new GNSS receiver technologies are meeting the need for more accurate navigation Location, location, location October/November 2018 | Unmanned Systems Technology GNSS receivers increasingly come with several hundred channels and the ability to track signals from three satellite networks at a time (Courtesy of Lockheed Martin)