Patent ID: 8326363
Filing Date: 2012-12-04
Classification: G01S

Abstract:
1. A portable terminal comprising: a communication unit that transmits/receives a signal modulated by a predetermined modulation method to/from three or more base stations; a storage unit which stores in advance a plurality of propagation models indicating propagation environments of the signal for respective combinations of the base stations and stores in advance position information of the base stations; and a control unit that controls the communication unit and the storage unit; wherein the control unit specifies a propagation model that corresponds to a combination of the base stations among the plurality of propagation models stored in the storage unit based on the signal and calculates communicable distances of the signal based on the corresponding propagation model, calculates circles having the corresponding communicable distances as their radii and having positions of the base stations as their centers, respectively, obtains an overlapping area where the circles overlap one another, and specifies the center position of the overlapping area as the position of the portable terminal.