Sources¶

Every external claim in this directory is anchored here. Each entry records what it was used to support, so a reader can check the claim against the source rather than trust the summary.

Access date for all links: 2026-09-29, unless a publication date is given separately.

Source types are distinguished, because they are not equally strong:

Type	Weight
`PEER-REVIEWED`	Strongest. Peer-reviewed journal or conference paper.
`GOVERNMENT`	Official government or agency publication.
`VENDOR`	Company press release or product page. Authoritative for what a company claims, not for performance.
`PREPRINT`	Not peer-reviewed at time of access. Treated as provisional.
`INSTITUTIONAL`	Standards body, professional society, or survey publisher.

S1: GNSS receiver autonomous integrity monitoring: research status and opportunities¶

Review article, Frontiers in Physics, 25 June 2025. DOI 10.3389/fphy.2025.1567301. Type: PEER-REVIEWED

Used to support: that receiver integrity monitoring is an established research area with its own survey literature; and, as reported within that review, that ship groundings were attributed to excessive positioning deviation in January 2024 and that up to roughly 1,500 flights per day were subjected to GPS spoofing across the first three quarters of 2024.

https://doi.org/10.3389/fphy.2025.1567301

DARPA. Program page. Marked "This program is now complete." Type: GOVERNMENT

Used to support: that GNSS denial, jamming, and blocked environments are long-standing publicly funded research problems; that improved inertial measurement units, signals of opportunity, and plug-and-play sensor reconfiguration are established programme areas. Notes GPS access is "easily blocked by methods such as jamming".

https://www.darpa.mil/research/programs/adaptable-navigation-systems

S3: DARPA Subterranean Challenge¶

DARPA. SubT program page and challenge final event page. Type: GOVERNMENT

Used to support: that GNSS-degraded autonomous navigation is an established public research framing, and that DARPA identifies autonomy, perception, networking and mobility as the four technical gaps.

https://www.darpa.mil/research/programs/darpa-subterranean-challenge https://www.darpa.mil/research/challenges/subterranean

S4: Hexagon completes acquisition of Septentrio¶

Hexagon press release, 19 March 2025. Announced 7 January 2025. Type: VENDOR

Used to support: that "resilient, assured positioning" is an active commercial category, and that robotics, UAVs and autonomy are named target segments.

https://hexagon.com/company/newsroom/press-releases/2025/hexagon-completes-acquisition-of-septentrio-expanding-the-reach-of-mission-critical-navigation-and-autonomy-applications

S5: Septentrio company and product information¶

Septentrio. About page, and mosaic-G5 P8 product announcement, 18 May 2026. Type: VENDOR

Used to support: that receiver-level anti-jamming and anti-spoofing capability is a commercial product category, distinct from estimator-level fault detection.

https://www.septentrio.com/en/about-us https://www.septentrio.com/en/company/news/septentrio-unveils-mosaic-g5-p8-ultra-resilient-gnss-module

S6: NIST request for comment on PNT; Satelles response¶

National Institute of Standards and Technology. Public comment record, July 2020. Type: GOVERNMENT

Used to support: that backup and complementary PNT capability is an active public policy and standards workstream, with industry responses on record.

https://www.nist.gov/document/pnt-rfi-response-satelles-inc

AFWERX / SpaceWERX. Challenge overview. Type: GOVERNMENT

Used to support: that over-reliance on GNSS is treated as a public challenge-framed problem.

https://afwerxchallenge.com/spacewerx26/altpnt/overview

S8: Physical consequences of GNSS interference, as reported publicly¶

Reported figures are cited within S1, drawn from OPSGROUP civil-aviation spoofing statistics and news reporting on port groundings. Type: INSTITUTIONAL (secondary; see S1 for the review that compiles them)

Used to support: that GNSS interference has documented operational consequences, not only theoretical ones.

Note: the underlying statistics are third-party and were not independently verified here. They are cited only as reported in a peer-reviewed review.

S9: BlackNaute resilient PNT¶

Safran. Press release, June 2025. See also the company's resilient-PNT explainer. Type: VENDOR

Used to support: that resilient PNT is a marketed commercial product category.

https://www.safran-group.com/pressroom/blacknaute-resilient-pnt-revolution-against-threats-global-navigation-satellite-systems-gnss-2025-06-16 https://safran-navigation-timing.com/how-resilient-pnt-works-in-gps-denied-environments

Hesch, J. A., Kottas, D. G., Bowman, S. L., Roumeliotis, S. I. IEEE Transactions on Robotics 30(1), pp. 158–176, 2014. DOI 10.1177/0278364913509675. Type: PEER-REVIEWED

Used to support: the central claim of this directory: that inconsistency and overconfidence in vision-aided inertial navigation is a characterised, published problem traceable to a mismatch between the observability of the linearised estimator and that of the true system.

https://doi.org/10.1177/0278364913509675

S11: Observability-based rules for designing consistent EKF SLAM estimators¶

Huang, G. P., Mourikis, A. I., Roumeliotis, S. I. International Journal of Robotics Research.* Type:PEER-REVIEWED`

Used to support: the origin of the observability-mismatch framing, and that filter design rules for consistency were published years before this repository.

Cited within S14 and the survey literature.

S12: High-precision, consistent EKF-based visual-inertial odometry¶

Li, M., Mourikis, A. I. International Journal of Robotics Research 32(6), pp. 690–711, 2013. Type: PEER-REVIEWED

Used to support: that consistency-first filter design for visual-inertial odometry is established prior work.

Huang, G. MIT Computer Science and Artificial Intelligence Laboratory. Type: PREPRINT (technical report, not peer-reviewed at time of access)

Used to support: that state-transition-constrained and observability-constrained formulations are an active remedy family.

https://people.csail.mit.edu/ghuang/paper/tr/stocvins.pdf

S14: FEJ2: A consistent visual-inertial state estimator design¶

Chen, C., Yang, Y., Geneva, P., Huang, G. IEEE ICRA 2022. NSF Public Access record. Type: PEER-REVIEWED

Used to support: that first-estimate-Jacobian methods, and their refinements, are established; and to source the S11 and S12 citations.

https://par.nsf.gov/servlets/purl/10376064

S15: OpenVINS: a research platform for visual-inertial estimation¶

Geneva, K., Eckenhoff, K., Lee, W., Yang, Y., Huang, G. IEEE ICRA 2020, pp. 4666–4672. Type: PEER-REVIEWED

Used to support: that an open, established visual-inertial reference implementation exists and is the natural comparison baseline for this repository, which does not currently use it.

Cited within S16.

Tian, C., He, F., Hao, N. arXiv:2511.17992. Type: PREPRINT

Used to support: that the consistency problem in visual-inertial navigation was still being actively re-analysed, and is not a closed problem.

https://arxiv.org/abs/2511.17992

Critchley-Marrows, J. J. R., Verspieren, Q. Space Policy 72, 101665, May 2025. DOI 10.1016/j.spacepol.2024.101665. Open access, CC BY. Type: PEER-REVIEWED

Used to support: the policy framing of PNT resilience as a matter of national concern.

https://doi.org/10.1016/j.spacepol.2024.101665

S18: Resilience of A-PNT systems compared with traditional PNT systems¶

Diachenko, A. / Oscilloquartz, ADTRAN. WSTS presentation, May 2024. Type: VENDOR

Used to support: a vendor-side taxonomy of alternative PNT sources, including LEO satellite PNT, signals of opportunity, and ground-based systems.

Explicitly not used to support any technical or performance claim; vendor decks are treated as marketing for that purpose.

https://wsts.atis.org/wp-content/uploads/2024/05/07_Resilience-of-APNT-systems-compared-ADiachenko-1.pdf

S19: Autoware vision_pilot¶

Autoware Foundation. Open-source repository. Type: INSTITUTIONAL

Used to support: that a public, productionizable, safety-certifiable L2 ADAS software stack exists, as a concrete example of where an estimator of this type would be integrated.

https://github.com/autowarefoundation/vision_pilot

S20: DARPA non-GPS PNT programme overview¶

DARPA PNT programmes briefing, presented 2019. DoD Distribution Statement A: approved for public release; distribution unlimited. Archived by the National Geospatial-Intelligence Agency. Type: GOVERNMENT

Used to support: that alternative PNT, ultrastable clocks, cold-atom inertial sensing, and signals of opportunity are long-running research areas.

Supporting commentary: Physics Today, "DARPA looks beyond GPS for positioning, navigating, and timing", 9 October 2025. https://physicstoday.aip.org/news/darpa-looks-beyond-gps-for-positioning-navigating-and-timing

https://archive.gps.gov/governance/advisory/meetings/2019-06/burke.pdf

S21: Survey on opportunistic PNT with signals from LEO communication satellites¶

Stock, W., Schwarz, R. T., Hofmann, C. A., Knopp, A. IEEE Communications Surveys & Tutorials 27(1), pp. 77–107, February 2025. DOI 10.1109/COMST.2024.3406990. Type: PEER-REVIEWED

Used to support: that opportunistic PNT is an active research area with survey- level treatment.

https://doi.org/10.1109/COMST.2024.3406990

S22: Septentrio and Xona Space Systems memorandum of understanding¶

Septentrio, 7 October 2025. Type: VENDOR

Used to support: that LEO PNT receiver development is an active commercial activity, and is an example of an alternative signal source this repository does not implement.

https://www.septentrio.com/en/company/news/septentrio-and-xona-sign-mou-accelerate-adoption-next-era-navigation-technology

Proceedings of the International Technical Meeting of the Satellite Division of the Institute of Navigation. DOI 10.33012/navi.612, 2023. Type: INSTITUTIONAL (peer-reviewed conference proceedings)

Used to support: that navigation safety assurance for GNSS/IMU Kalman filters is an active, published topic, and that this repository does not engage it.

https://doi.org/10.33012/navi.612

Sources deliberately not used¶

Vendor or aggregator company profiles (for example business-data platforms) were not used as sources. They were not needed: every organisation in the mapping is anchored to a first-party public page.
Secondary news coverage was not used where a primary or peer-reviewed source was available.
Any non-public, internal, or classified material was not used, and none is required to read this directory.