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Galileo Notes: Ephemeris, Anomalies, I/NAV, SFRBX - Bert Hubert's writings
a day ago
- The author uses a Navilock NL-8012U with a u-blox 8 chipset, configuring it via u-center to enable Galileo and NMEA 4.1 for raw data.
- Galileo ephemeris parameters in semi-circle units require multiplication by π for calculations.
- Eccentric anomaly is computed through iteration (E = M + e * sin(E)), often in 10 iterations.
- True anomaly can be calculated using an approximation formula for near-circular orbits, with extra terms for elliptical orbits (e.g., e=0.162).
- Extracting ephemeris parameters from I/NAV messages involves parsing word types 1-4 with specific bit positions and sign handling.
- Coordinates in ECEF GTRF are derived using standard orbital mechanics, and elevation is calculated as 90° minus the angle between user and satellite vectors.
The State of Galileo as seen by an outsider - Bert Hubert's writings
a day ago
- Galileo is a civilian EU GNSS managed by the European Commission, built by ESA, and operated by the GSA via Spaceopal, with a complex multi-layered governance structure.
- The July 2019 week-long outage was caused by multiple simultaneous failures (backup unavailable, mishandled upgrade, system anomalies), but communication was poor and the EC blamed a single person.
- The constellation has only 21 functional satellites (below 24), leading to coverage gaps, and frequent 'No Accuracy Prediction Available' (NAPA) status due to ground software issues.
- Software fixes are slow due to a long chain from vendor to ESA to GSA to Spaceopal, and many satellite failures are expected before the next launch (likely 2021).
- The galmon.eu open source project provides independent 24/7 monitoring of Galileo and other GNSS, uncovering under-reported issues.
- Galileo's search and rescue component performed well and remained available during the outage.
- EU governance upheavals (creation of EU Space Agency) and tensions with ESA may further delay improvements.
- The author recommends better transparency, independent monitoring, and structural reforms to address communication and expertise gaps.
The July Galileo Outage: What happened and why - Bert Hubert's writings
a day ago
- The July Galileo outage was caused by multiple simultaneous failures: backup system unavailable, mishandling of new equipment during an upgrade, an anomaly in the system reference time, and a non-normal configuration.
- Communication during the outage was poor, with the European Commission being the sole communicator and far removed from operations.
- Galileo's operational complexity involves many organizations, leading to slow resolution of ground-based software problems and a culture of secrecy.
- Despite the outage, the constellation could restart in a few days, but 5% of satellites are often unavailable due to software issues.
- The SDD allows for up to 6.9 days of outage in a 30-day period, so the outage technically met minimum performance levels.
A 2019 update on PowerDNS, Galileo, DoH and other things - Bert Hubert's writings
a day ago
- Joined the RIPE NCC Community Projects Fund selection committee and became a member of the Europol Communication Providers Advisory Group.
- Handed over daily management and technical leadership of PowerDNS to the team, remaining in a spiritual leadership role.
- Launched galmon.eu, a community-driven project monitoring all GPS satellites (including Galileo, BeiDou, GLONASS) in real time.
- Opposed centralized DNS over HTTPS (DoH), arguing for encrypted DNS without moving traffic to third parties, and engaged in activism on the issue.
- Worked on a book about DNA, but progress was slow; expects more news in 2020.
- Galileo project gained industry attention and uncovered oddities in satellite operations, with positive response from the GNSS community.
The new Galmon.eu Weekly Galileo Report - Bert Hubert's writings
a day ago
- Announcement of the first full Galmon.eu Weekly Galileo Report, summarizing a good week with minimal issues.
- The report is a blog post version of an earlier Twitter thread, available via email or online.
- Motivation: to provide helpful public insight into Galileo's performance, despite existing internal reporting.
- Galileo is important for European independence in satellite navigation, though its technical and managerial systems are complex.
- A 6-day outage a year ago highlighted a lack of public transparency, prompting the creation of a worldwide GNSS monitoring platform.
- The platform, built with over 60 station operators and open data sources, enables near real-time reporting.
- Many helpful individuals within the Galileo project (engineers, scientists, etc.) educated the author, but the culture remains closed, with anonymous communication.
- The report aims to increase visibility and serve as a public reference, contributing to the project's improvement.
Multi-Signal GNSS & the Curious Case of Galileo E24: Part 1 - Bert Hubert's writings
a day ago
- Multi-frequency GNSS removes over 99% of ionospheric delay by combining signals at different frequencies.
- Galileo uses an 'ionosphere-free clock combination' as its official time signal, but internal satellite delays cause small clock offsets.
- Single-band receivers (like phones) must apply a correction term (BGDE1E5a/b) to compensate for the combined clock adjustment.
- Galileo has two clock combinations (E1/E5a and E1/E5b), each with separate clock parameters (af0) that receivers must match correctly.
- Satellite E24 shows a persistent ~5 nanosecond (1.5 meter) clock bias in correction feeds, due to a mismatch in clock references.
- NAVCAST corrections convert E1/E5a clocks to E1/E5b clocks, causing the bias, which is resolved by using I/NAV clock parameters.
- The issue arises from an undocumented RTCM standard and the choice of I/NAV as the reference clock for corrections.
- Offline SP3 files also show the bias, but only when compared to the wrong clock reference (I/NAV instead of F/NAV).
- The af0 parameters between F/NAV and I/NAV clocks differ by 5.8789 ns for E24, closely matching the observed bias.
Galileo's Proposed Authentication Algorithm: Part 1 - Bert Hubert's writings
a day ago
- GNSS authentication is needed to prevent PVT spoofing, as current systems broadcast unauthenticated data.
- Galileo's OSNMA uses the TESLA protocol for efficient message authentication with limited bandwidth (40 bits per message).
- Symmetric signatures are used with delayed key disclosure; keys are generated in a chain so each key derives previous ones.
- Occasional public key signatures provide a trust anchor, allowing verification of the entire key chain.
- Receivers must not use disclosed keys to verify future messages; time synchronization is critical to prevent attacks.
Galileo's Proposed Authentication Algorithm: Part 2 - Bert Hubert's writings
a day ago
- Galileo's OSNMA uses a hierarchical message structure: pages (40 bits for OSNMA: 8 HKROOT, 32 MACK), 15 pages per subframe, 24 subframes per frame.
- The HKROOT field carries the Digital Signature Message (DSM), which includes a signed root key and configuration parameters, transmitted over multiple subframes.
- The MACK field contains MAC signatures and keys, but not for the page it's in; it signs bundles of data from the transmitting satellite and others, including GPS and BeiDou.
- Key verification follows TESLA: keys are disclosed later, and receivers derive the key's position in the chain using timestamps and subframe rate, then verify against the signed root key from the DSM.
- OSNMA is complicated by constraints: simple satellite hardware (bent-pipe), limited ground uplink capacity, and the need to authenticate out-of-reach satellites and other GNSS systems.
- MACK blocks are per subframe (1-3 blocks per subframe), each containing MACs and a key; the key ID is computed from the timestamp and the number of blocks per subframe.
Galileo's Ground Segment Problem - Bert Hubert's writings
a day ago
- Galileo's ground segment has limited uplink capacity, often contacting only 13 of 24 satellites simultaneously, causing occasional accuracy issues.
- On September 25, 2020, satellite E11 accumulated a 5-meter error due to lack of ground contact, highlighting the need for more robust communication.
- Aging satellites like E11 require frequent ephemeris updates every 10 minutes, but without ground contact they continue broadcasting a healthy status, potentially misleading users.
- On October 27, 2020, two new dishes were added to the ground segment, partially addressing the capacity problem.
- The ground segment's underinvestment (despite Galileo's €10 billion cost) contrasts with satellite reliability, leading to chronic uplink shortages and calls for autonomous fault signaling.
- Adding 'Working Without Guarantee' functionality to all satellites would improve system integrity by marking them faulty if out of contact.
Galileo's Testing Communications - Bert Hubert's writings
a day ago
- Galileo is a successful EU satellite navigation system offering advanced services like High Accuracy Service (HAS) and cryptographic assurance (OSNMA), but its communication about disruptions remains poor.
- In May 2025, a cryptic NAGU notice warned of possible service degradation due to testing, with no details; the test involved long periods without satellite updates, causing clock drift and positioning errors.
- Professional users received no useful response from EUSPA, and the agency declined to comment on the article, highlighting a pattern of denial and miscommunication about past outages.
- The author urges the EU and EUSPA to improve communication with users by providing clear, timely updates and avoiding tests that risk service disruption.

Hasty Briefsbeta

galileo

Galileo Notes: Ephemeris, Anomalies, I/NAV, SFRBX - Bert Hubert's writings

The State of Galileo as seen by an outsider - Bert Hubert's writings

The July Galileo Outage: What happened and why - Bert Hubert's writings

A 2019 update on PowerDNS, Galileo, DoH and other things - Bert Hubert's writings

The new Galmon.eu Weekly Galileo Report - Bert Hubert's writings

Multi-Signal GNSS & the Curious Case of Galileo E24: Part 1 - Bert Hubert's writings

Galileo's Proposed Authentication Algorithm: Part 1 - Bert Hubert's writings

Galileo's Proposed Authentication Algorithm: Part 2 - Bert Hubert's writings

Galileo's Ground Segment Problem - Bert Hubert's writings

Galileo's Testing Communications - Bert Hubert's writings