Patent ID: 7961146
Filing Date: 2011-06-14
Classification: G01S

Abstract:
1. A positioning method in a positioning device that calculates a location of the positioning device by executing Kalman filtering, comprising: acquiring a satellite signal from a positioning satellite; predicting a state vector including a velocity component of the positioning device, and error covariance of the state vector; correcting the velocity component using a difference between a measured value and a predicted value of the reception signal frequency from the positioning satellite; determining accuracy of the corrected velocity component based on the error covariance; setting a velocity condition based on the determined accuracy, the setting the velocity condition including setting a threshold value of the velocity lower, as the determined accuracy becomes higher; judging a moving state of the positioning device by comparing the corrected velocity component and the threshold value of the velocity condition; changing a filter characteristic of the Kalman filtering based on the judged moving state; and calculating the location by executing the Kalman filtering with the filter characteristic after being changed.