GPS Network RTK Performance Under VeryActive Ionospheric Conditions

摘要

The traditional RTK method only needs one referencernstation, and is capable of providing cm accuracy for staticrnpositioning and dm accuracy for kinematic positioningrnunder normal atmospheric conditions when the interantennarndistance is less than approximately tenrnkilometres. However, under localized high atmosphericrnactivity, the increase in the residual differential errors canrndegrade position accuracy substantially. An effectivernmethod to improve position accuracy under suchrncircumstance is to use network RTK. This method uses arnnetwork of GPS reference stations to model thernatmospheric conditions over the geographic regionrncovered by the network, and then to provide users withrncorrections of spatially correlated errors. Applying theserncorrections can reduce the residual double differencedrncarrier phase errors, thus improving the ambiguityrnresolution and the accuracy of the rover's position.rnThe differential ionospheric errors have a major impact onrnthe improvement provided by the network RTK method.rnPrevious research has shown that the network method canrnyield significant improvement under normal ionosphericrnconditions. To have a thorough understanding of therncapabilities and limitations of the network RTK method,rnthis paper focuses on evaluating its performance underrnvery active ionospheric conditions. Results of this methodrnand the traditional RTK method are compared to assessrnthe quality of the network corrections. After comparison,rnit is found that in a medium scale network, the networkrnRTK method fails to provide more accurate solutionsrnunder such harsh ionospheric conditions. Some datarnprocessing strategies are recommended to improve roverrnreceiver positioning.