A dual-antenna heading determination method for single-frequency GNSS antennas with large phase pattern variations

Precise applications, including dual-antenna heading determination, have been flourishing research fields in global navigation satellite system (GNSS). However, due to the requirements for strong GNSS models and precise carrier phase measurements, single-frequency antennas with large phase pattern variations are difficult to be adopted. In this research, a search-based heading determination method is demonstrated and verified. A new ambiguity resolution (AR) method, namely baseline heading and length-constrained LAMBDA (HLC-LAMBDA), is also proposed to attempt the AR under a weak GNSS model as well as help identify a rough heading estimate among all listed heading candidates (HC). During the heading search (HS) process, all HCs are evaluated individually with relative positioning results between two antennas, and each HC being evaluated serves two functions: 1) helping correct the antenna-induced phase biases by applying a predetermined phase pattern with different attitudes, and 2) acting as a rough heading constraint in the HLC-LAMBDA method. The performance of the proposed method is analyzed in terms of the precision of heading and relative positioning solutions, the elimination of antenna-induced phase biases, and the computational efficiency; and test results utilizing a phase pattern measured in an anechoic chamber and the data in both static and kinematic cases are also shown, illustrating a consistent conclusion that, under the condition of single-frequency measurements and large phase pattern variations, the proposed method can provide heading solutions with a root mean square error (RMSE) of around 0.07°.