Then according to the voidness of GPS satellites in different position, the effect on navigation accuracy of GPS (that is GDOP) is studied.The validity of voidness strategy is proved by simulation.

• 首先分析了GPS卫星对特定区域的覆盖情况，然后针对不同位置的GPS卫星失效，考察对GPS导航精度即目标区域GDOP值的影响，并通过仿真予以验证。