Low-latency jamming mitigation in SWaP-constrained GNSS analog CRPAs via hierarchical dithered null steering

Global Navigation Satellite Systems (GNSS) underpin critical functions in modern society, from autonomous ground vehicles and unmanned aerial vehicles to civil infrastructure and defense operations. Yet, the extreme weakness of GNSS signals at the Earth's surface makes them acutely vulnerable to intentional jamming, threatening the reliability of safety- and mission-critical applications. Controlled Reception Pattern Antennas (CRPAs) with analog beamforming offer a compact, power-efficient defense against jammers, but mitigation remains difficult: the literature on analog CRPAs is sparse, and existing approaches often rely on naïve grid searches that are too slow for deployment and prone to failure in practice. In this paper, we introduce a hierarchical search framework tailored to the constraints of analog CRPAs. Our method combines binary refinement with lightweight dithering to overcome fundamental pitfalls of grid-based null steering, where mismatches between null width and grid resolution obscure the jammer's direction. By exploiting suppression contrast as a guiding signal, the algorithm identifies and resolves ambiguous cases without resorting to exhaustive probing. Simulations with a four-element analog CRPA demonstrate mean jammer suppression levels of nearly 50 dB while reducing measurement complexity by approximately 96% on average compared to exhaustive search (up to 98% in the best case), making low-latency operation feasible on size-, weight-, and power (SWaP)-constrained GNSS receivers.