Self-Contained Implementation of Nullsteering and Beamforming with a Standalone Antenna Array for GNSS Signals under Interference.

The implementation of adaptive array processing such as the minimum variance distortionless response (MVDR) requires the knowledge of a reference waveform or a reference direction (steering vector), which is unfortunately not always available to a standalone antenna array especially from a cold start in GNSS applications. A self-contained implementation that cascades pre-correlation nullsteering and post-correlation angular estimation and beamforming is set forth in this paper. The proposed method suppresses jamming by projecting the array outputs onto the jamming nullspace, thus preserving the spatial information for subsequent processing. In the jamming nullspace, the baseband signal processor adopts a master-slave architecture where the same code and carrier replicas drive all channels to maintain phase coherency. Spatial combining, non-coherent in acquisition and coherent in tracking, is used for three intertwined code, carrier, and angular tracking loops. Post-correlation angular estimation can be further used for attitude determination. Test results under realistic jamming conditions are presented that demonstrate the system functionality and performance.