T/R-R high frequency surface wave radar (HFSWR) can detect over-the-horizon sea targets which are hundreds of miles away.The earth curve should be taken into consideration when determining target position using the measurement information obtained by HFSWR.We present sphere positioning algorithm to calculate target position and corresponding accuracy.Weighted least square (WLS) method is applied to sphere positioning algorithm to improve positioning accuracy.Computer simulations are leaded to analyze deviation of target position obtained by plain positioning algorithm.GDOP of sphere positioning algorithm using WLS method is also simulated.We conclude that sphere positioning algorithm can eliminate position deviation.Besides

sphere positioning algorithm using WLS method improves target positioning accuracy.