jgg     2011 31 (4):  144-148    ISSN: 0412-1961  CN: 21-1139/TG STUDY ON SELECTION OF PS POINT TARGETS Long Sichun 1,2) ; Li Tao 3) ; and Feng Tao 2) 1)School of Resources and Safety Engineering of Central South University, Changsha 410083;2)Hunan Key Laboratory of Clean Coal Resources Utilization and Mine Environment Protection, Hunan University of Science and Technology , Xiangtan 411201;3)GNSS Engineering Research Center, Wuhan University, Wuhan 430079 Received: 1900-01-01  Revised: 1900-01-01  Online: null Supporting info null