CRPA Beamformer Spoofer Nulling for GNSS Attitude
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Solution Overview
Problem
GNSS receivers are vulnerable to spoofing attacks, where false signals trick the system into incorrect position, velocity, and time estimates, leading to potential accidents or errors in navigation and tracking.
Innovation Solution
A controlled reception pattern antenna (CRPA) system with a beamformer and processor that steers a main lobe to survey directions and nulls out signals from spoofers by identifying increased signal power associated with multiple space vehicles, thereby determining the spoofer's location and adjusting the antenna pattern to counter the spoofing attack.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the main lobe is steered to survey all directions in space, then the ability to detect spoofer signals is improved, but the time required to determine attitude increases
Solution Approach 1:
The system performs preliminary spoofer detection by surveying signal directions before final attitude determination. The beamformer pre-identifies spoofer locations by detecting abnormal signal power concentrations, allowing the attitude determination algorithm to exclude these directions and converge faster to the correct attitude solution.
Solution Approach 2:
The attitude determination process is segmented into two phases: (1) spoofer detection phase where the main lobe surveys directions to identify fraudulent signals, and (2) attitude determination phase where only authentic satellite directions are used. This segmentation prevents spoofer signals from corrupting the attitude solution and reduces iterative computation time.
2Reliability
If the CRPA nulls out spoofer signals, then the reliability of position and time reporting is improved, but the complexity of the antenna system increases
Solution Approach 1:
The beamformer acts as an intermediary between the CRPA elements and the signal processing system. It dynamically forms nulls in the directions of spoofer signals by adjusting the phase and amplitude weights of individual antenna elements, effectively filtering out fraudulent signals before they reach the attitude determination algorithm while maintaining simple hardware architecture.
Solution Approach 2:
The antenna system transitions from a static omnidirectional pattern to a dynamic adaptive pattern that automatically reconfigures nulls to track moving spoofer sources. The beamformer continuously adjusts the null directions based on real-time spoofer detection, providing reliable protection without requiring manual intervention or complex mechanical adjustments.
Data Source
AI summary
Disclosed is a technique to estimate at least a portion of an attitude, such as an azimuth angle from true North, based on beam angles from a controlled reception pattern antenna (CRPA) to space vehicle locations. Other attitude information such as roll and/or pitch can also be estimated. The at least portion of the attitude can be provided with or without an additional sensor, such as a compass or magnetometer, an inertial measurement unit (IMU), or the like. An attitude estimate can be useful because oftentimes the attitude of an object can vary from its track or velocity direction.