Method of and apparatus for detecting vehicle speed pulse drop, on-vehicle navigation system, program storage device and computer data signal embodied in carrier wave

摘要

An on-vehicle navigation system is provided with a radio wave positioning apparatus (18) and a vehicle speed sensor (13) for a dead reckoning positioning. A method of detecting a vehicle speed pulse drop of a vehicle speed pulse generated by the vehicle speed sensor is provided with: a first calculation process of calculating a first physical quantity of a predetermined type such as a velocity or the like from radio wave positioning data of the radio wave positioning apparatus; a second calculation process of calculating a second physical quantity of the same type as the first physical quantity from the vehicle speed pulse; and a detection process of detecting the vehicle speed pulse drop by using a contradiction caused between the calculated first physical quantity and the calculated second physical quantity as a detection condition.