jgg     2014 34 (3):  129-132    ISSN: 0412-1961  CN: 21-1139/TG MODELING RECEIVER CLOCK ERROR IN GPS/INS TIGHTLY  INTEGRATED NAVIGATION Institute of Geo-Spatial Information，Information Engineering University，Zhengzhou 450052 Received: 2013-08-12  Revised: null  Online: 2014-05-28 Supporting info