According to the report, the Global Positioning System GPS due to various errors, the absolute positioning accuracy in real terms will not satisfy many applications some corrections must therefore be applied to the observations of the position of the spot. That's why the effects of various errors and how to deal with these errors has been expressed, the principle of DGPS system performance is discussed. Purpose of obtaining DGPS corrections system to eliminate or reduce errors affecting the accuracy. these corrections can be used to reach the desired accuracy of the navigation system and other matters related to the conduct of the instantaneous position can be used. The basic working principle based on the instantaneous position of the GNSS receiver is at least two. Consideration of the limitations of single-reference systems constraints on the communication system, reduces the accuracy and validity of the submitted corrections with increasing distance - is therefore a reference system are discussed. So the four permanent stations TKCE, KHJE, AHAR, SKOH method for determining the relative position is estimated. The results show that increasing the distance between the station elevation corrections increase the amount and accuracy of the method decreases. Thus it can be concluded that to reduce the adverse effects of these reference stations, the situation is more difference between the position of the unknown station to be deleted In this case, the proposed model is a linear combination of being able to review and remove stations that lowers accuracy DGPS system will be.