Illustrative: satellite orbits, their ground swaths or the lines of sight a receiver keeps
Risk Academy, led by the Nexus Consortium · Technology and Digital Systems · Department of Cyber, Digital and Space Systems
Satellite positioning and timing, the threats to them and the backups
Positioning, navigation and timing resilience
Phone networks, power grids, payment systems and aircraft all take position or time from satellites, often without their operators knowing how much.
- Courses
- In preparation
- Levels
- In development
- Labs
- In development
- GNSS systems and signals
- Timing for telecommunications, power and finance
- Jamming and spoofing
- Space weather effects on GNSS
- Interference detection and monitoring
- Backup PNT: eLoran, fibre timing, inertial and signals of opportunity
- Resilient receivers and holdover clocks
- Aviation and maritime GNSS interference
- PNT resilience policy and standards
Build a twin of any place
Search any place or open the world; the layers and generators follow positioning, navigation and timing resilience on the planet map, the globe and in 3D.
- Terrain 0 to 245 m
- 4 satellite dishes
- 74 communication masts and towers
- 12 telephone exchanges
- 7 data centres and cable landing stations
- 12 aerodromes
- 1 telecom offices
- Communication line 161 km
- 729 known exploited vulnerabilities since 2023-10-17
- Night-time lights, VIIRS day-night band: read live when the 3D twin opens
Drag to move, right drag or Shift with a drag to turn and tilt, Ctrl with the wheel to zoom. Keyboard: arrows move, Shift with arrows turn and tilt, + and – zoom, 0 resets, V steps through the views, Escape clears.
Flat plan of the same data: relief as contours from the inline grid, the mapped ground infrastructure by kind, the mapped cables and the numbers below. The 3D twin opens on devices that can draw it, once its data and code have been checked.
The boundaries, names and designations shown do not imply any judgement on the legal status of any territory, or any endorsement or acceptance of such boundaries. Countries: Natural Earth (public domain).
The subject, methods and measures and debates and bodies
The field and its scope
For telecommunications, energy, finance and transport operators, receiver engineers and policy staff who must know how their services depend on satellite timing and positioning and how to keep running without it.
Quantities and units
Methods and their limits
Each method is listed with what it assumes and where it fails.
What the field debates
Bodies that set practice, and the data they publish
Bodies and standards are named so that learners can find and apply their published work. The Academy teaches the use of that work and links to the publisher. No affiliation is implied.
From a lost satellite signal to a timing budget: how long a site can hold over
When the satellite signal is jammed or spoofed, a site's clock drifts from the frequency offset it had at the moment of loss plus its ageing; the accumulated time error against the budget a network tolerates fixes the hours the site can run on holdover, and the resilience decision is about the clock class and the complementary source.
Sources: Psiaki and Humphreys, GNSS Spoofing and Detection (2016); Ioannides, Pany and Gibbons, Known Vulnerabilities of Global Navigation Satellite Systems, Status, and Potential Mitigation Techniques (2016); Sadlier, Flytkjaer, Sabri and Herr, The economic impact on the UK of a disruption to GNSS (London Economics) (2017); Executive Order 13905, Strengthening National Resilience Through Responsible Use of Positioning, Navigation, and Timing Services (2020).
At a glance, hub and courses
Positioning, navigation and timing resilience at a glance
risksacademy.comtechnology-digitaldiscipline
- Open, 0
- In preparation, 0
- Subtopics, 9
Research and tools
Research and preprints as they are published, by discipline, with the faculty's other tools.
The hub lists the newest research and preprints for Positioning, navigation and timing resilience, each with its source and date. Open the research hub
Courses in this discipline
Courses for this discipline are in development. Until they open, study the discipline through the connected courses and open lessons below.
The course catalogue lists every open course of the Academy.
How Positioning, navigation and timing resilience is taught, as a process you can run
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Process explorer
How Positioning, navigation and timing resilience is taught
14 steps5 stages
Achievements, where this is practised, practised in and across the ecosystem
Achievements in this discipline
Course achievements
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Where the subject is practised
A field platform page on this subject is in development.
The two Foundry systems where it is practised
- FoundryNXS-SIG systemPositioning, navigation and timing integrityPNT Integrity room
- NXS-NET systemNetworks depend on timing to stay synchronisedContinuity room
Foundry system pages describe what each system and its rooms are designed to do; the courses teach the methods these systems apply.
Across the ecosystem
Take part in Technology and Digital Systems
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Core references and where to begin
Start with Ioannides, then Psiaki, then Volpe National Transportation Systems Center.
Questions, answers and key terms
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Key terms
Spoofing
Broadcasting false GNSS signals so that a receiver computes a wrong position or time.
Jamming
Transmitting radio noise that prevents a receiver from tracking GNSS signals.
Holdover
The time a clock can keep accurate time after losing its reference signal.
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Reports is the Consortium's quarterly publication. What you know about this subject can become evidence, a case or a correction in the next edition, credited to you and published under CC BY 4.0 where it is your own work.
Around Positioning, navigation and timing resilience
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