Session A2: GNSS Security: Interference, Jamming, and Spoofing 1

Combining ADS-B, LCM and DPA to Detect and Locate the Interference in a Massive GNSS Jammer Test
Yu-Hsuan Chen, Zixi Liu, Argyris Kriezis, Sherman Lo and Todd Walter, Stanford University
Location: Beacon A

GNSS signals are vulnerable to Radio Frequency (RF) interference. When navigating by the GNSS sensor and encounter abnormal behavior, one needs an efficient approach to detect the interference and respond instantly. Stanford GPS Lab developed ADS-B [1], Low-cost monitor (LCM) [2] and Dual polarization antenna (DPA) [3] to provide robust GNSS spoof detection and jamming mitigation. ADS-B uses Navigation Integrity Category (NIC) broadcasted from aircraft as indication how GNSS on board impacted by interference . The localization algorithm developed in [4] achieved decent accuracy. However, the NIC has indirect relationship with jamming power and affected by the other source like aircraft dynamics. LCM connects low-cost GNSS receiver and small computer to collect the power measurement and jamming/spoofing indication. If multiple LCMs are deployed across the area, we can divide the whole area into several regions. By gather all the information from LCMs, we can determine which region has the highest impact of interference. DPA is an antenna can determine the azimuthal direction of arrival (DOA) of incoming GNSS signals using just a single GNSS patch antenna. The DPA has both of right hand circularly polarized (RHCP) and left hand circularly polarized (LHCP) components that can combine one polarization by the other one with phase shift. The composite signal then is either fed into a commercial off the shelf (COTS) receiver. The power measurement of composite signal from different phase shift can then determine the DOA of incoming signal. Alternatively, taking the carrier phase measurement between two polarizations by a Software Defined Radio (SDR) or a commercial receiver with two inputs. Stanford GPS lab has made a prototype printed circuit board (PCB) implementing DPA with above two modes, SDR and COTS. With two of DPAs deployed, we can cross the directions of DOAs to localize the interference.
We brought all three equipment of ADS-B receiver, LCMs and DPAs to a massive jammer test 2024 held in Norway [5]. The test is likely the largest civilian PNT/GNSS jammer test in the world. And this is the first opportunity that we can examine all three approaches at the same event. During five-day test period, various spoofing and jamming scenarios are broadcasted including multiband jammer and positioning/timing spoofing. As mentioned in the first section, ADS-B, LCM and DPA have its limitation or uncertainty. One combining method is firstly using ADS-B to locate the potential area. Second, LCM zooms in to smaller region. Third, bring two DPAs in that region to localize interference. In the paper, we provide algorithms and hardware of ADS-B, LCM and DPA and the jamming test results are discussed.
[1] Liu, Zixi, Lo, Sherman, Blanch, Juan, and Walter, Todd
Identifying the Source of October 2022 Texas Jamming Incident Using ADS-B Data with an Improvement in the Model Confidence
Published in Proceedings of the 2024 International Technical Meeting of The Institute of Navigation, Long Beach, CA, January 2024.
[2] Kriezis, Argyris, Chen, Yu-Hsuan, Akos, Dennis, Lo, Sherman, and Walter, Todd
GNSS RFI Detection and Impact Characterization in Various Interference Environments using Low-Cost Receivers
Published in Proceedings of the 37th International Technical Meeting of The Satellite Division of the Institute of Navigation (ION GNSS+ 2024), Baltimore, MD, September 2024.
[3] Lo, Sherman, Chen, Yu Hsuan, Rothmaier, Fabian, and Walter, Todd
Demonstrating and Improving the Performance of a GNSS Dual Polarization Antenna (DPA) for Spoof Detection in Flight
Published in Proceedings of the 35th International Technical Meeting of The Satellite Division of the Institute of Navigation (ION GNSS+ 2022), Denver, CO, September 2022.
[4] Liu, Zixi, Blanch, Juan, Lo, Sherman, Chen, Yu-Hsuan, and Walter, Todd
Real Time Detection and Estimation of GNSS Interference Affected Region using ADS-B Data and Bayesian Modeling
Published in Proceedings of the 36th International Technical Meeting of The Satellite Division of the Institute of Navigation (ION GNSS+ 2023), Denver, CO, September 2023.
[5] Jammertest2024 website link, https://jammertest.no/jammertest/