This paper is devoted to the problems of creation of local differential system (LDS) of GNSS. Mobile network GSM is used as a transmission channel of correcting information. LDS is based on geodesic control correcting station (GCCS) and satellite double frequency navigation equipment “INVESTIGATION”. Such system will help to increase accuracy of position determination to decimeters values by special modem adding to user equipment GNSS. Access for mass using by Yekaterinburg citizens is one of LDS advantages. Another LDS advantage is entire creation on the base of Russian equipment. Besides, this article solves the problems of precise coordinate connection of antenna GCCS phase centre and creation of navigation equipment LDS user.