jgg     2009 29 (3):  141-144    ISSN: 0412-1961  CN: 21-1139/TG ANALYSIS AND IMPROVEMENT OF ACCURACY OF GPS POINT POSITIONING OBSERVATIONS Wang Ping 1) ;Hao Jinming 1) ;Sheng Guokang 2) ; and Wang Haoyu 3) 1)Institute of Surveying and Mapping, Information Engineering University, Zhengzhou 4500522)92899 Troops, Ningbo 3152003)78138 Troops, Chengdu 610036 Received: 1900-01-01  Revised: 1900-01-01  Online: null Supporting info null