Patent ID: 6865394

Claim:
A positioning method of calculating a position of a receiver according to propagation delay time of signals from a plurality of wireless transmitters, comprising: a first step of detecting a signal from each of the wireless transmitters, obtaining a position of each of the wireless transmitters from which the signal is detected, measuring propagation delay time of the signal from each of the wireless transmitters, and calculating a position of the receiver and a standard deviation about measuring distance error associated with the measurement of the propagation delay time; a second step of calculating a positioning error of the receiver according to the position of each of the wireless transmitters and the position of the receiver and the standard deviation calculated in said first step; a third step of determining, according to the positioning error of the receiver calculated in said second step, wireless transmitters in directions nearer to a direction in which the positioning error is large; and a fourth step of re-detecting signals from the wireless transmitters in directions nearer to a direction in which the positioning error is large determined in said third step and thereby re-calculating the position of the receiver.