GPS Spoofing Detection via Carrier Phase Angle of Arrival
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Solution Overview
Problem
Satellite navigation systems are vulnerable to 'spoofing' signals that deceive receivers, making it difficult to determine whether received signals are legitimate or bogus, leading to degraded performance or inoperability.
Innovation Solution
A method using a GPS receiver system with multiple antenna elements and a processing unit to measure carrier phase differences, calculate the angle of arrival of signals, and compare it with expected angles to verify signal legitimacy, while also mitigating interference by adjusting the antenna pattern to null out unwanted signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a GPS receiver system uses multiple antenna elements to detect spoofing signals by measuring carrier phase differences and calculating angle of arrival, then the ability to identify illegitimate signals is improved, but the device complexity increases
Solution Approach 1:
The receiver system is segmented into multiple antenna elements, each independently measuring carrier phase of incoming signals. This segmentation enables the system to calculate angle of arrival by comparing phase differences between elements, providing spoofing detection capability while keeping each antenna element relatively simple in structure
Solution Approach 2:
The patent introduces a processing unit as an intermediary that receives carrier phase measurements from multiple antenna elements, calculates angle of arrival, and compares it with expected angles from ephemeris data. This intermediary component coordinates the complex interactions between multiple antennas and the navigation solution, managing the overall detection process
2Object-affected harmful factors
If the antenna pattern is adjusted to null out unwanted spoofing signals, then the mitigation effect is improved, but the responsiveness to legitimate satellite signals may be reduced
Solution Approach 1:
The antenna pattern is adjusted to create directional nulls at specific angles where spoofing signals are detected, while maintaining high gain in other directions where legitimate satellite signals arrive. This local quality adjustment allows selective rejection of harmful signals from specific directions without affecting reception of legitimate signals from satellite directions
Solution Approach 2:
The system continuously monitors carrier phase differences and calculated angle of arrival to detect spoofing signals, then provides feedback to adjust the antenna pattern accordingly. This closed-loop feedback mechanism ensures the antenna nulls are dynamically positioned to counteract detected spoofing while preserving legitimate signal reception
3Measurement precision
If carrier phase measurements are taken at multiple antenna elements to calculate angle of arrival, then the precision of spoofing detection is improved, but the difficulty of detecting and measuring increases
Solution Approach 1:
The system performs preliminary coherent measurements of carrier phase at each antenna element before calculating angle of arrival. By establishing consistent measurement timing and reference phases across all antenna elements in advance, the system simplifies the subsequent angle calculation process and reduces measurement complexity
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Effectively detects and mitigates spoofing signals, ensuring navigation accuracy by identifying illegitimate signals and reducing their impact on the receiver, while maintaining responsiveness to legitimate satellite signals.
Implementation Method 1
measure carrier phase differences, calculate the angle of arrival of signals
Implementation Method 2
mitigating those signals by adjusting the antenna pattern to null out the illegitimate signals
Data Source
AI summary
A system and method for testing the integrity of signals incoming to a satellite navigation system. The method is implemented with an array of antenna elements, and a receiver connected to each antenna element. The receivers simultaneously and continuously make measurements on all tracked signals. Each receiver measures the carrier phase of an incoming signal. Based on the carrier phase differences between antenna elements and the distance between them, the azimuth and elevation of the signal source can be calculated. This measured angle of arrival can then be compared to an expected angle of arrival to determine if the signal source is legitimate. The system and method can be also applied to determining the angle of arrival of sources of interference, and to mitigating the effects of both illegitimate and interfering signals.