| 摘要 |
<P>PROBLEM TO BE SOLVED: To enable a terminal device and a geomagnetic environment determination program to restrain influence of disturbing magnetism around a point of observation and thereby to prevent the reliability of autonomous positioning from deteriorating. <P>SOLUTION: A terminal device comprises a geomagnetism detector that detects geomagnetism in triaxial directions orthogonal to one another; an acceleration detector that detects accelerations in triaxial directions; a vertical component calculator that calculates a vertical component resulting from projection of a geomagnetic vector in a vertical direction, the vector representing geomagnetism based on the detected geomagnetism and accelerations; a dispersion calculator that calculates dispersion of the calculated vertical component in a given length of time; and a geomagnetism likelihood determiner that determines a geomagnetism likelihood representing the reliability of the geomagnetism on the basis of comparison of the dispersion and a threshold and outputs the likelihood. <P>COPYRIGHT: (C)2013,JPO&INPIT |
