Position accuracy for 3-D curved surface in bistatic high frequency surface wave radar

Bistatic high frequency surface wave radar(HFSWR) transmits vertically polarized high frequency wave propagating over coastal surface to detect nautical and aerial targets,the earth's curvature cannot be ignored.Target altitude formulations are established on a spherical coordinate system for different measurement subsets,the geometric dilution of precision(GDOP) is also conducted.Experiments demonstrate the GDOP of different subsets on variable flight altitude,the optimal distribution map of measurement subsets is also derived.