Method of and apparatus for detecting angular velocity, method of and apparatus for detecting angle, navigation system and computer program therefor

A method of detecting an angle is provided with processes of: setting a bias voltage, as a standard voltage, which is an output voltage outputted from an angular velocity sensor (12) under a predetermined condition; and calculating the angle on the basis of a difference between the output voltage and the set or updated standard voltage. It is further provided with processes of storing time data, which indicate a time of setting or updating the standard voltage, in correspondence with standard voltage data; estimating a value of the bias voltage of the angular velocity sensor at each time between times of setting or updating the standard voltage; and correcting the calculated angle on the basis of a difference between a value of the standard voltage used in the calculation process and the estimated value of the bias voltage.