jgg     2012 32 (2):  143-147    ISSN: 0412-1961  CN: 21-1139/TG INTER-SATELLITE LINKS ANALYSIS OF WALKER CONSTELLITE Yang Xia; and Li Jiancheng School of Geodesy and Geomatics, Wuhan University, Wuhan 430079 Received: 1900-01-01  Revised: 1900-01-01  Online: null Supporting info null