Abstract: GNSS attitude determination is increasingly applied in various navigation and positioning fields due to its cost-effectiveness. Navigation and positioning modules in the consumer market often employ low-cost receivers, which face challenges such as significant multipath effects, frequent cycle slips and integer ambiguities, among others. In complex urban environments, ambiguity fixing, a crucial component of GNSS attitude determination, encounters even more challenges. In this paper, based on the C-Lambda algorithm, we propose the C-Lambda-Search and C-Lambda-A Search methods. These methods involve a search for the degrees of freedom of another attitude angle when fixing ambiguities with a single baseline. They are employed to perform global minimization of the ambiguity function in both the attitude and ambiguity domains, aiming to calculate baseline vectors. We conduct static and dynamic vehicle experiments with three low-cost receivers (ublox-M8T) and patch antennas in different environments with varying baseline lengths.Both experiments demonstrate that the methods proposed in this paper significantly improve ambiguity fixing performance and Euler angle calculation accuracy. Furthermore, the computational burden remains within an acceptable range. These methods prove to be practical and effective for vehicle attitude determination.

Key words: GNSS, inexpensive, attitude resolution, single epoch single item, ambiguity fixed