Absolute Reference Correlation SOLD (ARCSOLD)

ABSTRACT: Q-Track proposes to develop and demonstrate feasibility of a system for absolute localization in GPS-denied environments. A Signals-of-Opportunity Location Device ("SOLD"), previously demonstrated to yield 1m repeatable location indoors, provides the desired"absolute location reference. Q-Track"s proposed SOLD sensor a compact, lightweight tag ultimately costing about $50 in volume also creates"Virtual Landmarks"that allow the system to combine location estimates from multiple users at various times so as to yield improved location estimates. With uncorrelated errors, the location estimate improves approximately as square root n where n is the number of user passes through the Virtual Landmark, converging to the 30cm accuracy with which SOLD defines Virtual Landmarks. We estimate the system is feasible for a 200MHz processor with memory of about 774kB/user/hour. With algorithm optimization and improvements in database management, the algorithm may be made substantially more efficient. Q-Track will field-test how the system improves the accuracy of GPS and other location data. In addition, Q-Track"s approach has the ability to serve as a GPS back-up, providing GPS-quality location estimates (or better) in urban areas where Signals-of-Opportunity are present but GPS signals are unavailable or marginal due to jamming, interference, or line-of-sight blockage. BENEFIT: The proposed effort enables existing location estimate errors to be improved approximately as the square root of n where n is the number of users passing through a Virtual Landmark location up to the approximately 30cm accuracy with which the Virtual Landmark is defined using the Signals-of-Opportunity. Once a sufficient density of Virtual Landmarks have been determined using an expensive, high precision indoor navigation system, further navigation through the area may be accomplished using a compact, lightweight tag device costing about $50 in volume. We believe the accuracy and simplicity of the proposed system will allow Q-Track to unlock the indoor navigation market - ultimately an opportunity likely larger than the $30B outdoor location market served by GPS.