POSITION FINDING APPARATUS

PROBLEM TO BE SOLVED: To provide a position finding apparatus capable of finding the current position with high accuracy and on a real time basis even when a relatively large receiver clock drift occurs.SOLUTION: A position finding apparatus 20 comprises a receive signal analyzer 21 that analyzes receive signals; a receiver clock 22 that provides reception time information to the receive signal analyzer 21; and a Kalman filter 40 that estimates the position of a user, the velocity of the user and the receiver time, wherein the Kalman filter 40 is provided with state predicting means 41 that predicts a state, state estimator 42 that estimates the state and clock abnormal variation detector 43 that detects any abnormal variation in the receiver clock 22, the state predicting means 41 being further provided with a state predictor 41a that predicts a state variable vector of the current epoch on the basis of a state variable vector of one epoch before obtained from the state estimator 42 and a predicted state value corrector 41b that corrects the predicted state value on the basis of the result of detection by the clock abnormal variation detector 43.