Transmit time & orbit
Navigation satellites broadcast ranging signals and navigation data supported by precise onboard clocks.
The satellite navigation briefing & learning resource
Understand satellite navigation.
Follow its evolution.
Explore the principles behind GNSS, understand Galileo and EGNOS, and make sense of the developments shaping positioning, navigation and timing.
Four signal paths · Position fix
Simplified projected geometry, not to scale. Real visibility, geometry and measurement quality vary.
Understand the technology. Follow the developments.From satellite signals to real-world applications ↓
Featured education reference
GNSS Academy.
A reference for satellite navigation education worldwide.
Connecting GNSS theory, practical engineering and professional development through specialised programmes for engineers and company teams.
Discover GNSS Academy ↗EDUCATION / ENGINEERING PRACTICEFrom understanding
From understanding
to doing.
Founded by aeronautical engineer Eduardo Tapias, GNSS Academy brings industrial satellite-navigation experience into structured learning. Its approach combines technical foundations, workshops and practical project work.
1,000+Professionals trained
500+Master JSNP participants
25 yearsFounder’s experience
Explore the educational approach +
Master JSNP offers a six-month online journey combining theory, engineering tools, an end-to-end project and expert conversations. GROW provides an intensive in-person format, while specialised programmes support deeper technical learning and company teams.
The shared objective is to connect concepts with processing decisions, testable outputs and engineering judgement.
Featured organisation: GNSS Academy. Figures and programme descriptions supplied by the Academy. This profile is not an independent ranking.
GNSS technology, explained
How do signals from space
become your position?
GNSS means Global Navigation Satellite System. Constellations such as Galileo, GPS, GLONASS and BeiDou transmit radio signals carrying precise timing and orbit information. A receiver measures their travel times to estimate its location and time.
In a conventional unconstrained solution, at least four independent satellite pseudoranges are needed to estimate three position coordinates and the receiver clock offset. Additional measurements can improve geometry and redundancy; accuracy also depends on the environment and processing.
Measure travel time
The receiver tracks signals to form pseudorange, carrier-phase and Doppler measurements.
Model & estimate
Algorithms account for satellite motion, clock offsets, atmosphere and other measurement errors.
Deliver useful PNT
Position, velocity and time support transport, surveying, agriculture, robotics and infrastructure.
Performance is more than accuracy: integrity, availability, continuity and resilience matter too.
Satellite Navigation Briefing
What’s moving
the sector forward.
Selected developments from original institutional sources, with our perspective on their relevance to engineering.
CONSTELLATIONG2EUROPEAN NAVIGATION / BRIEFING
Four more satellites for Galileo’s next generation
ESA has procured four additional Galileo Second Generation satellites, taking the planned G2 fleet to 16.
Our engineering perspective: constellation evolution connects payload design, system qualification and long-term service continuity.
Read our briefing →GROUND SEGMENTGROUNDEUROPEAN NAVIGATION / BRIEFING
Preparing the ground for Galileo G2
ESA reports contracts for new ground stations to support the modernisation of Galileo’s ground segment.
Our engineering perspective: ground infrastructure is a useful entry point into operations, algorithms, performance and system engineering.
Read our briefing →RESILIENT PNTTRUSTEUROPEAN NAVIGATION / BRIEFING
Galileo demonstrates authenticated positioning
A real-world test combined navigation message authentication and authenticated ranging to demonstrate Galileo SAS positioning.
Our engineering perspective: authentication makes receiver processing, threat modelling and validation increasingly relevant skills.
Read our briefing →Editorial selection checked 1 November 2026. Source publication dates are shown on each story. Engineering perspectives are our interpretation; the linked organisations do not endorse this website. This selection is updated editorially, not automatically.
Europe’s satellite navigation programmes
Galileo and EGNOS.
Two distinct roles.
One provides global navigation signals. The other adds regional corrections and integrity information. Together, they illustrate the breadth of European PNT engineering.
Global navigation satellite system
Galileo
The European Union’s global satellite navigation system delivers positioning, navigation and timing. Its space segment, ground infrastructure and user receivers work together to support applications worldwide.
- Open Service: positioning and timing for civil users.
- High Accuracy Service: precise corrections for compatible receivers.
- OSNMA: authentication of navigation message data.
Engineering spans orbits, clocks, signals, ground systems, receiver processing and service performance.
Explore Galileo at EUSPA ↗Satellite-based augmentation system
EGNOS
The European Geostationary Navigation Overlay Service augments GPS over its European service area. Ground monitoring and processing generate corrections and integrity information, relayed to users through geostationary satellites.
- Corrections: reduce selected GNSS measurement errors.
- Integrity: helps supported users assess positioning reliability.
- Applications: aviation, maritime and other demanding uses.
Current GPS augmentation is distinct from the planned evolution to dual-frequency, multi-constellation services including Galileo.
Explore EGNOS at EUSPA ↗Original explanatory illustrations; simplified architectures. Programme descriptions reference EUSPA. No institutional endorsement is implied.
Start with understanding
The technology behind a connected world.
Satellite navigation supports mobility, mapping, precision agriculture, autonomous systems and the timing infrastructure that connects modern economies.
Open the introductions below, then explore the engineering topics further down the page.
Explore the engineering library ↓01What is GNSS?+
A constellation of possibilities.
Global Navigation Satellite Systems provide signals that receivers use to estimate position, velocity and time. The complete chain connects satellite orbits and clocks, signal propagation, receiver measurements and estimation algorithms.
02Galileo & EGNOS+
Different roles. Connected services.
Galileo is Europe’s global satellite navigation system. EGNOS augments satellite navigation over its service area, providing corrections and integrity information. Understanding their different architectures helps engineers connect system design with user needs.
03Precise positioning+
From measurements to precision.
RTK and PPP use carrier-phase measurements and correction information to improve positioning. Their performance depends on the observation environment, correction quality, ambiguity handling and implementation—not simply the name of the technique.
04Resilient PNT+
Accuracy is only part of the story.
Positioning, navigation and timing also need continuity, integrity and robustness. Engineers assess interference, faults and degraded conditions, and develop detection, authentication or complementary-sensor strategies appropriate to the application.
Engineering topics / introductory library
Build a connected
understanding of GNSS.
Short educational introductions for students, engineers and curious professionals. Open a topic to begin.
Orbits & clocks
Why does a satellite’s orbit matter?
Read the introduction +
A receiver needs the satellite position at signal transmission time. An orbit error therefore contributes to the range model used in positioning. Satellite clock offsets also enter this model; a timing error becomes a distance error when multiplied by the speed of light. Orbit and clock information must be interpreted with their time tags and reference conventions.
Signals & receivers
What does a GNSS receiver measure?
Read the introduction +
A receiver tracks coded radio signals to form pseudorange, carrier-phase and Doppler observations. Acquisition finds a signal; tracking follows its code delay and carrier behaviour over time. A measurement is not yet a position: estimation combines observations with navigation data, error models and quality checks.
Positioning techniques
How do SPP, RTK and PPP differ?
Read the introduction +
Single Point Positioning uses broadcast navigation information with pseudoranges. RTK exploits carrier-phase observations and reference information, often from a nearby base or network. PPP uses precise satellite products and observation models without requiring a local base in the same way. Convergence, ambiguity handling, correction availability and operating conditions affect the result.
Integrity & resilience
Can an accurate-looking solution still be wrong?
Read the introduction +
Yes. Accuracy describes closeness to truth, but a plausible coordinate alone does not establish trust. Integrity concerns confidence in the information and timely warnings when required performance cannot be met. Resilience addresses disturbances and degraded operation. Faults, interference and modelling errors need distinct detection and response strategies.
Systems & applications
What connects space, ground and users?
Read the introduction +
GNSS is a chain of interacting elements: satellites broadcast signals; ground infrastructure supports control and navigation information; receivers process observations; applications use the resulting position, velocity or time. Performance requirements depend on the use case. A surveying tool, an aircraft approach and a timing installation do not evaluate success in the same way.
Engineering methods
How do you turn a requirement into evidence?
Read the introduction +
Define the expected behaviour, inputs and acceptance criteria before implementation. Trace requirements through architecture, algorithms and tests. Include nominal cases, missing data and degraded conditions. Preserve assumptions, configuration and reference data so a result can be reproduced and its limits understood.
Choose your starting point
A pathway through the essentials.
Start with the big picture.
Understand signals, travel time and the four unknowns in a basic position solution.
Read how positioning works ↑Meet Galileo and EGNOS.
Learn the difference between a navigation constellation and a regional augmentation system.
Explore the programmes ↑Connect principles to developments.
Read source-linked briefings with clear separation between announcements and engineering interpretation.
Browse recent briefings ↑About this publication
Clear explanations.
Traceable sources.
SatelliteNavigation.eu is an educational and editorial initiative by Eduardo Tapias, founder of GNSS Academy. It publishes accessible GNSS explanations and selected developments for an international engineering audience.
Briefings link to original announcements and distinguish reported facts from editorial interpretation. Dates identify the underlying announcement and our own publication. Educational graphics are simplified illustrations, not operational system models.
The publication features GNSS Academy as its education reference. This relationship is disclosed here; references to ESA, EUSPA and European programmes do not imply their endorsement.
Questions or corrections →