Ground-Based Ultrawideband Multistatic Positioning System for VTOL Guidance and GPS Integrity Monitoring

Prototypes of a Ground based Ultrawideband Multistatic Positioning System will be built and tested. The system allows position determination of an aircraft using ground nodes that transmit very accurately timed (subnanosecond) short pulses and only propagation time differences are used to determine aircraft position. Two variants are Comms Mode (which uses an active node on the cooperating aircraft) and Radar Mode (which assumes no extra hardware on the aircraft). The advantage of Comms Mode is that its link budget is based on a 1/r^2 propagation loss so it is easy to achieve the required range coverage to 1000rsquo; altitude above a Take Off and Land area (TOLA); and that all processing for position determination can be done locally within the aircraft. The advantage of the Radar Mode is that it can detect non-cooperating aircraft in the service volume, but then has to transmit the position information to the aircraft by some other means. Radar Mode also suffers from the fact that the radar equation propagation loss is 1/r^4, limiting effective range at the low RF power levels desired.Phase II will begin by developing the hardware, firmware and software for a COTS based Comms Mode prototype. Five nodes will be built and tested on the ground and in flight. The work performed in Phase I to determine operating frequencies, waveforms, pulse coding, positioning algorithms will be realized in working hardware that will be tested. Phase II will also further develop Radar mode operation using same hardware by using multiple pulses and a coherent receiver architecture, though this will be at higher risk than Comms Mode. Flight testing will be carried out with two second generation GUMPS nodes that will be built using custom hardware in a low size, weight and power configuration. These will be based on the preliminary design from Phase I. A three-month flight test program will employ the second generation hardware on a commercial helicopter with ground nodes at its home base.TBD