Improving the speed of CORS Network RTK ambiguity resolution

Carrier-phase ambiguity resolution between CORS Network RTK reference stations is hampered because of the presence of differential ionospheric delays. As a consequence, after a (power) failure or when a new satellite rises above the cut-off elevation, the float ambiguity solution needs to converge before the integer ambiguities can be reliably estimated. These convergence times can be up to tens of minutes, depending on the distance between the CORS stations and the ionospheric conditions. In this paper we propose a processing strategy to improve the speed of CORS Network RTK ambiguity resolution based on current dual-frequency GPS. This strategy suggests to use the ionosphere-weighted model, incorporating the known CORS station positions and a priori information on the ionospheric delays, in combination with the LAMBDA method and Fixed Failure-rate Ratio Test.