An interruption-free hand-held positioning method and system, carried by a person, includes an inertial measurement unit, a north finder, a velocity producer, a positioning assistant, a navigation processor, a wireless communication device, and a display device and map database. Output signals of the...http://www.google.com/patents/US6415223?utm_source=gb-gplus-sharePatent US6415223 - Interruption-free hand-held positioning method and system thereof
