Earlier studies on Locus' new Loran technology demonstrated that Loran signals can be received in urban/indoor environments where GPS is unavailable, but additional development was needed to utilize Loran's advantages in these applications. Nevertheless, it is clear that a combination of technologies will be needed to meet US Army needs for handheld positioning and navigation systems. Locus has advanced its Loran technology, but for Loran to function as a sensor within an integrated navigation, positioning, and communication system, receiver size and power requirements must be reduced. Under an Army program, Multispectral Solutions, Inc. (MSSI) is developing an ultra wideband (UWB) range measurement radio system to determine the location of all nodes in an urban or indoor environment. Integration with GPS and Loran will ultimately be required to provide a reference datum. Locus, Inc. Phase I SBIR program will define the necessary development steps to enable use of Loran as an alternate sensor within an UWB system. The Phase I program investigates three key areas regarding size and power consumption of the existing Loran technology: antenna, signal acquisition chain, and receiver board. In addition, Locus will review UWB interface requirements with MSSI, and incorporate those requirements into the Phase II program