Patent ID: 8035554

Claim:
A device for measuring a position of a mobile station, comprising: first measuring means for measuring the position of the mobile station based on observed data including a carrier phase of signals from satellites using a one-epoch measuring method in which only the observed data is used, independently epoch by epoch, said one-epoch measuring method performing measuring without inheriting an integer ambiguity or an error covariance from the previous epoch; second measuring means for measuring the position of the mobile station using a previous determination result of the position of the mobile station and speed information representative of a speed of the mobile station; third measuring means for measuring the position of the mobile station using solutions of variables derived from previous determination results of the first or second measuring means; and controlling means for selecting one of the respective measuring means which is to execute a respective measuring process as the selected measuring means; and reliability calculating means for calculating reliability of the measurement result for the selected measuring means, wherein when the calculated reliability of the measurement result of the selected measuring means is lower than a predetermined reference value, the controlling means selects another measuring means as the selected measuring unit, the another measuring means executing a respective measuring process as the selected measuring means.