Fast Ambiguity Resolution Between Long-Range Base Stations Based on Sequential Adjustment

Sequential adjustment is commonly used for base station ambiguity resolution in long-range Network RTK.It is a very effective method with a strict theory that takes fully into account the correlation information between satellites as well as redundant observations. In previous research，a sequential adjustment formula is executed with unchanged parameters，however，the parameters usually change during the observation process;meaning that a sequential adjustment formula with unchanged parameters is unsuitable for Network RTK. In addition，old observation measurements are not stored during the sequential adjustment process，thus it is hard to update the normal equation after the ambiguides are fixed. To solve these two problems we use a sequential adjustment formula as well as a rigorous derivation process with changed parameters. Moreover，the update algorithm for the normal equation where ambiguities are fixed is proposed. Experiments with base station ambiguity resolution in long-range network RTK showed that the proposed sequential adjustment formula and update algorithm for the normal equation proposed are appropriate.