Ultrawideband Multistatic Positioning System

E. Heidhausen
University Research Foundation,
United States

Keywords: PNT, GPS, Multistatic, Positioning, Localization, A2AD, Autonomy


This effort is nearing a Phase II NASA, Ames SBIR completion. In support of Advanced Aviation Mobility (AAM), there is a requirement to provide positioning accuracy to air vehicles with both a VTOL and "Perched VTOL" takeoff and landing capability. Localized positioning via GPS alone has proven potential to be unreliable, denied, or decoyed. This is particularly critical where landing areas, such as Vertiports, plan their operations in complex urban environments that include missions during environmental restrictions such as fog, smoke, rain, and snow. To further complicate the need for safe mission execution is the desire to transition from human piloted control to full automation. The use of an ultrawideband mulitstatic system includes the distribution of four or more fixed RF transceivers (ground/landing platform mounted) around the landing area. These self-orienting transceivers will communicate with airborne transceivers (one per vehicle). Upon approach to a landing site, the vehicle transmits an interrogation pulse cueing the ground nodes to sequentially transmit a single nanosecond pulse. There is a 100msec delay between each transmitted pulse within the ground node array. FPGA processing determines the transmitted pulse timing which is compared among the timing of all ground nodes via; time-distance of arrival or, time-of-arrival that determines relative positioning to the ground nodes. If the ground nodes are surveyed, a Lat./Long./Elev. reference is available. Positioning updates ae provided at 10 samples per second. Tailored high gain repositionable antennas can accommodate links for both a pure vertical and low glide slope angle "Perched" approach to landing. Tested accuracies using two different suite designs have yielded 1.5" and 3.5" repeatable positioning within the last 10 feet. Connectivity ranges have exceeded 1000' and 100' between the two designs. The shorter-range variant was tested in order to provide UAV based retail package delivery drones with a GPS denied positioning alternative enabling all weather, alignment of the drone/package to their delivery mailboxes. Our effort has both commercial and DoD applications. It can be configured for expeditionary use such as to establish a landing zone on a highway median during foul weather for emergency medical vertical recovery. On scene personnel would walk the landing zone and distribute nodes at the outer boarders. This positioning system requires additional R&D before commercialization. A final size could be as small as 1/2 of a tennis ball. We have flown the UAV node on a 249g Mavic mini without any attempt to improve packaging size. Our overall technical approach has applications for near real time relative positioning of ships in harbors, construction equipment, personnel, swarming vehicles, autonomous recovery aboard a "mothership", and is likely to have the potential to be implemented utilizing existing 5G networks rather than the current nodes.