Positioning system utilizing GPS satellites

摘要

A positioning system is disclosed in which a rate of change DELTA DELTA f in a Doppler shift DELTA f of the radio wave transmitted from a GPS satellite is detected in order to determine whether or not an extraordinary radio wave as caused by a multi-path or the like is being received, and a GPS satellite from which an extraordinary radio wave is received is excluded from a group of GPS satellites which are utilized in a positioning calculation. A difference DELTA f between a signal frequency f0 transmitted from a GPS satellite and a signal frequency fR receiver is calculated, and a rate of change DELTA DELTA f in the difference DELTA f is also calculated. The position of a receiver is calculated on the basis of information transmitted from a plurality of GPS satellites for which the rate of change DELTA DELTA f is equal to or less than a first threshold value, or DELTA DELTA f