METHOD AND SYSTEM FOR MEASURING UNDERGROUND POSITION

摘要

PROBLEM TO BE SOLVED: To provide a method and system for measuring an underground position for simultaneously measuring ground three-dimensional coordinates at a plurality of underground positions. SOLUTION: From a plurality of reference positions R on known three-dimensional coordinates above the ground or in the ground, cyclic reference signals fr modulated by identification code strings P of strong autocorrelation but of weak cross correlation are transmitted on a rotating magnetic field 3 of a prescribed carrier frequency fc into the ground 2. A magnetic field measuring instrument 20 is disposed in a prescribed posture S at a measurement position Q in the ground 2, with three or more reception coil element groups 21 being mounted in a prescribed interrelation on the measuring instrument 20, to measure signals fq induced in the respective coil elements 21 by the magnetic field 3. Phasesτof the respective reference signals fr at the measurement position Q are detected based on a correlation between the signals fq in the respective coil elements 21 and the respective code strings P while detecting the directionsθRof the respective reference positions R from phase differencesΔτbetween coil elements of the phasesτof the respective reference signals fr, the prescribed interrelation of the element groups 21, and their postures S. The ground three-dimensional coordinates of the measurement position Q are calculated from the known three-dimensional coordinates and the directionsθRof the respective reference positions R. COPYRIGHT: (C)2006,JPO&NCIPI