Theoretical analysis of Walker constellation coverage to area target

To solve the problem of Walker constellation's continuous coverage on zonal target or global target,agroup of judgment theorem was put forward,and a method for solving the problem was given.Firstly,the symmetry of Walker constellation was used to get the minimum period of time which need to be analyzed.Then according to the topological relations of the satellites sub-traces,a division of the earth surface was found,and the minimum area that need to be analyzed was gotten.And then,a necessary condition and a sufficient condition of the minimum area's coverage were brought forward.At last,a necessary and sufficient condition for continuous single coverage and N-level coverage was given.The simulation results show that this method has accurate calculation result and high computational efficiency.