Cooperative Handheld Location Device Using Signals of Opportunity

We propose to develop a cooperative handheld location device (CHLD) using signals of opportunity (SOOP) to complement and substitute GPS wherever the latter becomes unavailable. Examples of signals of opportunity include the field and/or segment sync codes in digital radio transmissions (e.g., digital TV signals). The proposed cooperative positioning concept includes differential ranges between cooperative devices to the same SOOP source and the relative ranges between the cooperative devices. The cooperation among networked location devices not only allows them to choose the most appropriate positioning mechanism but also provides them with additional measurements to reduce the number of SOOP otherwise required. In addition to data exchange, the radio link between two cooperative devices also allows for estimation of their clock offset and relative ranging. In Phase I, the proposed concepts will be formulated, analyzed, and simulated in computer for performance prediction and engineering tradeoff. The Phase I approach will be translated into hardware/software prototyping in Phase II for testing and demonstration. BENEFIT: When successful, the proposed research will produce a cooperative handheld location device where GPS is not available. This will have great potentials in many military, homeland security, and commercial applications alike for positioning and navigation in urban and indoor environments.