Then a new method based on Kalman filter weighted by DOP is proposed according to the drawbacks of simple averaging method.

This paper expounds the principle of accuracy evaluation method of user equivalent range error(UERE) combining with DOP values,and provides two methods of evaluating system positioning accuracy which one is with single station DOP and the other is with global station DOP,the imitations prove that the two method of evaluating results are corresponded.

Along this idea this paper studies how to achieve accurate passive source localization by using time difference of arrival measurements with only one motive station,and also induces the GDOP formula on condition that the specific locations of stations are known.

The availability of the system is validated through the simulation of the area and six representative cities about Geometric Dilution Of Precision(GDOP)and N Asset Coverage.

In this paper the arrangement of four laser tracking interferometers is discussed and three kinds of the optimal arrangements of four laser tracking interferometers are obtained through minimizing the position dilution of precision of the measured point.