GNSS Spoof Detection Using TDCP and INS Acceleration Checks
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Solution Overview
Problem
Existing GPS spoofing detection methods are inadequate for real-time, accurate identification of spoofing events, particularly in military applications, due to reliance on less accurate techniques and insufficient computation of error-sizes in GPS-derived accelerations.
Innovation Solution
A system using a GNSS receiver, inertial navigation system (INS), and processor to perform spoofing tests by comparing GNSS-derived and INS-derived acceleration estimates, with time-differenced carrier phase computations and user-specified thresholds to detect spoofing or jamming events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If precise point positioning (PPP) is used to compute GPS-derived accelerations, then the computation can be performed, but the accuracy is reduced and it cannot provide accurate probabilities of error-sizes in real time
Solution Approach 1:
The patent replaces the computational PPP method with a direct kinematic approach using carrier phase measurements and INS data. Instead of solving the complex PPP mathematical model, the system uses time-differenced carrier phase observations combined with INS-derived accelerations to compute GPS-derived accelerations in real-time with high accuracy and proper error probability estimates
2Ease of manufacture
If low grade inertial sensors are used in the INS, then the system cost is reduced, but the accuracy of spoofing detection is degraded
Solution Approach 1:
The patent merges GPS receiver data with INS data in a tightly coupled architecture. By combining carrier phase measurements from the GPS receiver with acceleration data from the INS, the system creates a synergistic effect where the strengths of each sensor compensate for the weaknesses of the other, enabling accurate spoofing detection without requiring high-grade inertial sensors alone
3Reliability
If existing spoofing detection methods are used, then spoofing events can be detected, but accurate probabilities of error-sizes cannot be computed for real-time spoofing or jamming tests
Solution Approach 1:
The patent implements a feedback mechanism where the system continuously computes the difference between GPS-derived accelerations and INS-derived accelerations, compares this difference against a threshold based on computed error probabilities, and generates spoofing alerts when the threshold is exceeded. This closed-loop feedback enables real-time spoofing detection with quantified error probabilities
Data Source
AI summary
A system to detect spoofing or jamming of GNSS signals comprises a GNSS receiver onboard a vehicle; an onboard INS and an IMU for producing vehicle inertial measurements; and an onboard processor that receives data outputs from the GNSS receiver and INS. The processor performs a method comprising computing a time-averaged GNSS-derived acceleration estimate for the vehicle based on TDCP measurements received from the GNSS receiver; computing a time-averaged INS-derived acceleration estimate for the vehicle based on inertial measurements; producing a time-varying threshold, indicative of a spoofing or jamming event, based on a user-specified probability of false alarm or probability of missed detection; obtaining a difference between the time-averaged GNSS-derived acceleration estimate and the time-averaged INS-derived acceleration estimate; determining whether a magnitude of the difference is greater than the time-varying threshold; and generating a spoofing or jamming alert when the magnitude of the difference is greater than the time-varying threshold.