jgg     2011 31 (6):  39-42    ISSN: 0412-1961  CN: 21-1139/TG ANALYSIS BASED IN CODE GIM OF IONOSPHERIC TECANOMALY BEFORE EARTHQUAKE Liu Jun; Chai Hongzhou; Liu Changjian; Chen Ke ;and Chang Yifeng Institute of Surveying and Mapping, Information Engineer University, Zhengzhou 450052 Received: 1900-01-01  Revised: 1900-01-01  Online: null Supporting info null