| 摘要 |
PURPOSE:To take various errors which inherently exist in respective satellites into selection conditions for a satellite to perform highly accurate position measurement with respect to a GPS receiver for obtaining an optimum combination of satellites for highly accurate position measurement in position measurement utilizing GPS satellites. CONSTITUTION:For four satellites arbitrarily selected among satellites observed in the sky, a total of errors obtained in respective parts of a receiver measurement error detecting part 10, an orbit information error reading part 20, an ionized layer delay correction error calculating part 40 and a troposphere delay correction error calculating part 50 is obtained for each satellite. Then when the above relation is utilized in a vector S having the totals as elements, an error vector X for a combination of four satellites is obtained as X=(inverse matrix of H).S. This error vector X is calculated for any combination of four satellites obtained from those in the sky. The error vectors thus obtained are registered in a satellite selection table 85 in the order of magnitudes, and using four satellites of the minimum error vector combination allows highly accurate position measurement. |
