US Patent 7598856 Navigation aid for low-visibility environments

A navigation system for navigating in low visibility environments includes a portable detection unit which uses position and orientation sensors and/or wireless location to track the position of the portable detection unit relative to some reference location, such as a fire truck. The relative position of the portable detection unit, and thus its user, is then output to a visual display for viewing by the user so that the user may see his/her position in a dark or smoky environment. The system may also include portable beacons which may be left at landmarks so that the relative positions of the landmarks may be seen on the visual display.