MOBILE OBJECT POSITIONING SYSTEM

A mobile object positioning system includes a GPS signal receiver for receiving positioning radio signals from a plurality of satellites, calculating a present location of a mobile object in accordance with the positioning radio signal and outputting present location data at each of a plurality of calculating times. An electronic controller is provided for updating the present location data at each calculating time, storing the present location data, estimating an error of the present location data in accordance with the positioning radio signals and outputting error data at each estimating time. A vehicle velocity sensor is disposed on the mobile object for detecting the velocity of the moving mobile object and outputting a mobile velocity signal. The electronic controller determines a stationary condition of the mobile object in accordance with the mobile velocity signal and prohibits updating the present location data when a stationary condition of the mobile object is determined and a value of the error data at a present estimating time is larger than that at a last previous estimating time.