Abstract: A system, device and method for assisting navigation are disclosed. The system comprises at least one positioning support device and a personal portable wireless user device. The positioning support device is operable to be placed near a navigation feature and to communicate appropriate navigational information, including absolute position and relative position with respect to a navigational feature. The user device is operable to receive the navigational information and communicate it to a user. The method operates to permit users to independently navigate local, overland or underwater areas and is especially useful for persons who whose vision may be impaired.

Abstract: A communication and position locating system (2) suitable for air traffic control is described. Multiple satellites (40) are provided in two geosynchronous constellations. One constellation (e.g., 4 satellites) has a first closed ground track (14). The other (e.g., 2 satellites (161, 182)) has a different ground track (18) or is geostationary, located outside of the first ground track (14). Geolocation information is transmitted by the satellites (40) to aircraft (28) and ground stations (26) so that aircraft (28) can determine their current position. A pseudo range correction map is provided to the aircraft (28) by the base stations (26) to permit differential geolocation measurements. The satellites (40) include communication transceivers (80) so that aircraft (28) can communicate voice and data to other aircraft (28) and to the ground stations (26, 30, 32) and automatically report their position to air traffic control centers (30), e.g., via the satellites (40).