Mobile body e.g. aircraft, position and protection limit determining method, involves comparing protection limits for retaining greater limit as valid protection limit for readjusted position

摘要

#CMT# #/CMT# The method involves determining an estimated position of a movable body e.g. aircraft (1), at a time. Difference between satellite data values and values acquired during the time is calculated. The estimated position is readjusted according to acquired data if the difference satisfies a validity test. Another protection limit is calculated on readjusted position based on failure probability undetected by the validity test during the readjustment, and the latter and former limit are compared for retaining greater limit among the two as a valid protection limit for readjusted position. #CMT#USE : #/CMT# Method for determining a position of a movable body e.g. aircraft, and a protection limit around the position from satellite data that is obtained from satellite constellation using global positioning system. #CMT#ADVANTAGE : #/CMT# The method permits to detect defect of the satellite constellation and disturbance connected to environment of the aircraft whose impact on innovation is not detected, thus avoiding problems for the aircraft during flying at low altitude and during landing phase. #CMT#DESCRIPTION OF DRAWINGS : #/CMT# The drawing shows a schematic representation of satellite constellation present above horizon of an aircraft. 1 : Aircraft 2.2- 2.12 : Satellites.