SBIR Phase I: Active Radar Multi-Path Mapping for High-Precision Ranging Applications

The broader impact/commercial potential of this Small Business Innovation Research (SBIR) Phase I project derives from the fact that modern Real Time Location Service (RTLS) systems offer the potential to improve the efficiency of warehouses, offices, and hospitals, and to increase the safety of first responders during an emergency. The high-precision radio frequency (RF) ranging technology to be developed in this project is expected to enable new application areas that are out-of-reach with current RTLS systems. The proposed technology is expected to provide an accuracy improvement of three orders of magnitude over current state-of-the-art systems using low-cost of-the-shelf components, while also mitigating common technical problems with RF systems (such as poor performance due to multi-path RF reflections). If successfully developed, the proposed technology could enable the use of high-precision RF ranging for motion tracking, accurate indoor localization, robotics, high-value asset tracking, perimeter security, and accurate first-responder person tracking. This Small Business Innovation Research (SBIR) Phase I project investigates algorithms to mitigate multi-path issues in a novel RF-based RTLS system. RTLS systems rely on robust range estimates between participating nodes. Multi-path reflections are the most significant source of error for these ranging estimates, and reducing their effect has in the past proven difficult. Recent developments in narrow-band 2.4 GHz radios allow millimeter-accurate ranging techniques based on carrier-phase measurements, similar to differential GPS systems. External interference can be minimized by using the phase information of pure carrier tones, and "packetizing" the range measurements by hopping over multiple discrete frequencies. Adding an antenna array and fast switching between the antennas adds further capabilities, as the different antenna phase measurements can be combined into a steerable virtual antenna. This is similar to active radar systems, except that it is done using low-cost of-the-shelf components. By using distance information and virtual antenna angle combined with the different multi-path components, the proposed system is able to map RF reflecting objects, allowing higher-level algorithms to accurately pinpoint the location of a device in a room. The proposed technology offers a potential accuracy improvement of three orders of magnitude over existing methods.