Analysis of the PDOP of Walker Constellation

In this paper we analyze a variety of the PDOP values of Walker constellation by using numerical simulations.We study the parameters affecting the navigation availability——constellation orbital altitude/inclination, the number of orbital planes, the number of satellites, and relative phase indices.It is shown that when the number of orbital planes is 3, the value of PDOP can be less than 3 by using only 24 satellites, which is actually the smallest number of satellites to achieve PDOP<3.