Virtual baseline method for Beidou attitude determination – An improved long-short baseline ambiguity resolution method

Ambiguity resolution (AR) is a critical step for successful attitude determination using carrier phase measurements of a satellite navigation system such as Beidou. This paper proposes an improved method for AR in support of Beidou attitude determination based on the concept of a “virtual baseline”. In the traditional long-short baseline method, the short baseline is limited to a length less than half of the carrier wave length of the Beidou signals. In the proposed method, a virtual short baseline is formed by differencing two collinear baselines. The AR equations for virtual short and long baselines are derived and the factors impacting the AR accuracy are analysed. Numerical simulation studies were carried out to evaluate the performance of the proposed AR method. The simulation results confirmed that the proposed method is an improvement over the traditional approach -- not only is it easier to deploy collinear antennas but also it keeps the capability of epoch-by-epoch AR, which makes it immune to cycle slips and there is no need for initialisation of ambiguity searching.