ANALYSIS OF INTER-FREQUENCY CLOCK BIAS FOR
GPS BLOCK IIF SATELLITES
1）Hunan Provincial Key Laboratory of Coal Resources CleanUtilization and Mine
Environmental Protection，Hunan University of Science and Technology，Xiangtan 411201
2）Shanghai Astronomical Observatory，Chinese Academy of Sciences，Shanghai 200030
Abstract The inconsistency of three frequency carrier phases of Block IIF satellites (PRN01 with PRN25）causes difference between the satellite clock biases (SCBs）derived from L1/L2based ionospherefree linear combination and the SCBs obtained from L1/L5based ionospherefree linear combination.The SCBs’ inconsistency between L1/L2 and L1/L5 is called interfrequency clock biases (IFCBs).IFCBs of Block IIF satellites (PRN01，PRN24，PRN25，PRN27）were obtained by processing the data from 37 IGS network stations.Analysis for the features of these IFCBs indicates：1）The epochdifferenced method is more efficient than the undifferenced one；2）All the Block IIF satellites exist apparent IFCBs，whose magnitude are approximately in centimeter to decimeter；3）The periods of 12，6，8 and 4 h can describe the IFCBs’ periodic variation better than other period groups.4）The model is also suitble for PRN24 and PRN27 Block IIF satellites.
