Addressing Multipolarization Interference in GNSS: A Quantitative Measurement and Suppression Solution

The current research on the global navigation satellite system (GNSS) has progressively shifted from providing high-precision services to delivering robust services. Emerging as a prevalent GNSS anti-interference means, an antenna array can significantly enhance the array degrees of freedom (DOFs). However, multipolarization interference (MPI) consumes additional array DOFs, resulting in a drastic anti-interference deterioration. Currently, most studies merely qualitatively highlight the hazards of MPI, while the quantitative measurement methods and suppression solutions remain unclear. To resolve this issue, we first derive the MPI quantitative measurement model based on signal orthogonal subspaces. The antenna array gain norm (AGN) and antenna array polarization equilibrium difference norm (APEDN) are applied as evaluation metrics. Second, we propose the MPI suppression solution combining polarization equilibrium calibration and an adaptive moment estimation on the quasiunitary Stiefel manifold (QUSM-ADAM) algorithm. The former constructs the MPI suppression function under energy constraints, while the latter incorporates manifold characteristics of energy constraints to accelerate the function convergence. Finally, we conduct the semi-physical experiment to evaluate the MPI measurement model and suppression solution. Experimental results demonstrate that the AGN and APEDN diminish with an increase in elevation, while the MPI suppression effect improves. In particular, the proposed solution enhances the average suppression effect by more than 20 dB and converges in around 16 iterations, when the elevation and azimuth range of MPI direction of arrival (DOA) are both within 10°. It enables high-precision quantification of polarization distortions and real-time MPI suppression, directly enhancing the accuracy of GNSS signal integrity monitoring in instrumentation systems.