| 摘要 |
A navigation system for use on an automobile, for example, has a GPS positioning device for determining a present position thereof from radio waves transmitted from GPS satellites, and a stand alone type positioning device including an direction sensor and a speed sensor, for determining a present position thereof from direction data from the direction sensor and speed data from the speed sensor. A data processor selects data from the GPS positioning device or data from the stand alone type positioning device. The data processor selects the data from the GPS positioning device, and/or corrects a distance corrective coefficient for the speed sensor if a PODP value is equal to or smaller than a predetermined value, if speed data from the GPS positioning device is equal to or greater than a predetermined value, and if the difference between the speed data from the GPS positioning device and the speed data from the stand alone type positioning device is equal to or smaller than a predetermined value, and additionally if the data from the GPS positioning device has been obtained consecutively three times at time intervals each equal to or smaller than a predetermined value, and if the consecutive three data from the GPS positioning device are equal to or smaller than a predetermined value.
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