Patent ID: 7321420

Claim:
A survey system comprising a target and a surveying instrument that automatically tracks or collimates the target, the target comprising: a direction angle sensor that measures a surveying-instrument direction angle obtained when the target is directed toward the surveying instrument; and a measurement command means for transmitting the surveying-instrument direction angle and a measurement command to the surveying instrument, the surveying instrument comprising: an angle measuring means for measuring a target direction angle that indicates a direction of the target; a measurement means for automatically collimating the target and performing measurement when the measurement command is received; an angular-difference calculating means for calculating an angular difference between the surveying-instrument direction angle and the target direction angle; a target-direction-angle estimating means for calculating an estimated target direction angle from the angular difference calculated at last measurement and from the surveying-instrument direction angle transmitted from the target at present measurement; and a rotation means for directing a body of the surveying instrument in a direction of the estimated target direction angle.